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改訂:2026年8月12日

若くして死なない方法

著:ピーター・メグダル博士

この記事の使い方

医療上の免責事項: この記事は教育目的のものであり、医学的な助言ではありません。個別の指導については、必ずかかりつけの医師にご相談ください。.

読みやすい

若年者の突然死

疫学, 、疾患メカニズム、診断、および予防

抄録

突発性心室細動ではなく、一般的な医学用語として: 心臓突然死 35歳未満の人々における突然心臓死(SCD)は稀ではあるが、その発生率とは不釣り合いに重大な影響をも長期的にもたらす。何十年もの余命が残されている個人に発生し、しばしば疾患の最初の現れとなるからである。現代のサーベイランスによると、全米の大学アスリートにおける発生率は約63,682アスリート年につき1例であり、リスクは性別、人種、競技によって偏りが見られる。男性アスリートは女性アスリートの約3.8倍、黒人アスリートは白人アスリートの約2.8倍のリスクを抱えており、ディビジョンIの男子バスケットボール選手は調査されたコホートの中で最も高いリスクを有している。.

法医学の進歩に伴い、病因スペクトラムが変化した。 判決. 現代のNCAA(全米大学体育協会)で裁定されたコホートにおいて、, 肥大型心筋症 症例の約13%を占めており、これは過去の推定値よりも大幅に少ないが、国や登録制度によってその割合は大きく異なる。剖検で異常が認められなかった原因不明の突然死は、これらのデータにおいて約20%と、判定されたカテゴリーの中で最大の割合を占めており、 特発性左室肥大 さらに17%を占めている。剖検で陰性となった症例のうち、かなりの割合が、その後、以下の理由によって説明される。 分子解剖, 主に遺伝性の不整脈症候群として。.

本レビューでは、若年者における突然死の原因、身体活動が引き金となる理由、根本的な病態の発現と診断法、生理的な心臓適応と病理学的変化の鑑別、および予防に関する既知の知見について述べる。スクリーニングは、中心的な課題としてではなく予防の一要素として扱い、何を見つけ、何を見落とし、どのくらいの費用がかかり、どの点で公平性を欠くかというエビデンスに基づいて評価している。管理方針は、一律の競技参加禁止から個別の対応へと決定的にシフトしている。 意思決定の共有, 、継続的な参加によるリスクは従来想定されていたよりも低いことを示す結果データに裏付けられており、すべてのイベントを防ぐスクリーニング戦略は存在しないため、緊急時行動計画と迅速な除細動は依然として不可欠であり、十分に準備された環境においては、病院外での発生時をはるかに超える生存率をもたらします。 心停止 一般的に.

キーワード 突然死;アスリート;肥大型 心筋症; チャネル病; 事前スクリーニング; 心電図検査; 緊急時対応計画; 分子剖検

分かりやすい要約

このセクションは、家族、コーチ、アスリートに向けて書かれています。論文の残りの部分は医師に向けて書かれています。.

この論文の内容

若い人の心臓が突然止まることがあります。スポーツをしている時かもしれませんし、じっと座っている時かもしれません。その人は倒れ、呼吸をしなくなります。.

医師はこの突然の心停止を心臓突然死と呼んでいます。.

稀ではあるが、実際に起こることである。そして大抵の場合、何かがおかしいということに気づく最初の兆候となるのだ。.

本稿では、なぜそれが起こるのか、誰が最もリスクにさらされているのか、そしてそれに対して何ができるのかを考察する。.

心臓の働き

心を家だと思ってください。.

その家には 配管. 心臓の中枢部、すなわち心筋に燃料を運ぶのは血管である。.

その家には . 心臓の中心部、つまり血液を全身に送り出すために収縮する筋肉そのもののことです。.

その家には 配線. 心臓の中心には電気系統があり、それが筋肉に収縮のタイミングを伝え、一定の鼓動を保っています。.

これら3つのうちのどれか1つに問題があるだけで、心臓が停止することがある。.

3種類の問題

壁のトラブル. 心筋は過剰に厚くなったり、あるいは過剰に薄く引き伸ばされたりすることがあります。厚くなったり瘢痕化したりした筋肉は、その中を通過する電気信号を乱す可能性があります。.

配線の問題。. 筋肉は完全に正常に見えても、配線に異常がある場合があります。心臓が突然非常に速く鼓動し、血液を送り出せなくなることがあります。こうした異常のほとんどは家族から遺伝します。.

配管のトラブル. 血管が誤った場所から始まることがあります。大抵の場合、これによって問題が起きることは全くありません。しかし、激しい運動中には、血管が圧迫されて一瞬閉じてしまうことがあります。.

運動が大切な理由

運動がこれらの問題を引き起こすわけではありません。しかし、それが原因で問題が誘発されることはあります。.

一生懸命働くと、体中にアドレナリンが満ち、心臓が高鳴る。汗をかいて塩分が失われ、筋肉は急速にエネルギーを燃焼させる。.

健康な心臓であれば、これらはすべて問題ありません。しかし、隠れた疾患を持つ心臓にとっては、危険な不整脈を引き起こすきっかけとなり得ます。.

ひび割れた窓ガラスを思い浮かべてごらん。穏やかな日には何ともないが、強い風が吹けば割れてしまう。.

難しいところ:訓練は心を変える

ウエイトトレーニングをすると腕が太くなりますが、トレーニングによって心臓も大きくなります。それは普通であり、健康的です。.

しかし、トレーニングによって鍛えられた大きく強い心臓は、検査上では病気の心臓と非常によく似ていることがあります。この2つを見分けることは、この分野において最も困難な仕事の一つです。.

医師たちの腕は格段に上がった。20年前、検査は黒人アスリートのおよそ10人に4人を誤って心臓疾患があると判定していた。今日では、その数字は10人に1人未満にまで減っている。医師たちが、一部の心臓の波形は特定の集団の人々にとっては正常であると学んだからだ。.

警告標識

ほとんどの人は前触れをまったく経験しません。しかし、兆候がある場合、重要なのはこれらです:

  • 気絶、または気絶しかけること、, の間 運動
  • 運動中の胸痛
  • 突然始まり突然止まる、激しいまたはドクドクと脈打つ動悸
  • 同じ作業をしているチームメイトよりもはるかに息切れする
  • 50歳未満で突然亡くなった親しい家族

運動中の失神は最大の懸念事項です。人々はよく暑さや水分不足のせいだと考え、実際にそれが正しい場合もあります。しかし、まずは医師の診察を受けるべきです。.

テストでそれを見つけることができますか?

時々、しかし常にとは限らない。.

心電図(ECG)と呼ばれる検査があり、EKGと呼ばれることもあります。心臓の電気信号を読み取るもので、迅速で、安価で、痛みを伴いません。.

それは配線の問題や一部の壁の問題を見つけるのが得意です。.

しかし、それは空港の金属探知機のようなものです。多くのものを検知する一方で、見落とすものもあります。配管の問題を見つけるのは苦手で、異常がないのにビービーと鳴ることもあります。.

もう一つの落とし穴があります。今日受けた検査で異常がなくても、それがずっと先まで安全であることを意味するわけではありません。こうした問題の一部は、思春期の間にゆっくりと進行します。16歳時の正常な検査結果が、24歳時点での健康な心臓を保証するものではないのです。.

一番効果があるのは何ですか

すべてのテストがすべての問題を見つけられるわけではない。だからこそ、最後の防衛線が最も重要となる。.

倒れている人がいて、普段どおりの呼吸をしていない場合:

  1. すぐに救いを呼んでください。.
  2. 胸の中心を強く、速く押してください。.
  3. AEDを持ってきて、それを使ってください。.

AEDは多くのジムや学校に置かれている小さな箱です。心臓のリズムを調べ、必要な場合に電気ショックを与えます。リセットボタンのようなものだと考えてください。音声で指示を出してくれるため、誰でも使うことができます。.

最大の遅れは通常、電気ショックそのものではありません。人々が自分に見えているものを理解していないことです。心停止を起こした人はあえぐような呼吸をしたり、体が震えたりぴくついたりすることがあります。それは発作や単なる失神のように見えるかもしれませんが、多くの場合そうではありません。.

助けがない時間が1分長引くごとに、生存の確率は低下します。これに対する備えができている学校では、はるかに多くの人が生存します。.

最後にもう一つ:家族を確認して

これらの心疾患の多くは家族内で遺伝します。もし1人の患者に見つかった場合、兄弟、姉妹、両親、そして子供たちも検査を受けるべきです。.

これは死後においても同様です。解剖で何も見つからなかった場合でも、特殊な検査によって原因が判明することはよくあります。その答えが、今なお生きている親族を守ることにつながるのです。.

 

ディープダイブ

若年者の突然死

疫学, 、疾患メカニズム、診断、および予防

1. 適用範囲および定義

突発性心室細動ではなく、一般的な医学用語として: 心臓突然死 目撃された場合は症状の発現から1時間以内、目撃されていない場合は最後に生存が確認されてから24時間以内に起きた、心臓疾患が原因の予期せぬ死亡と従来定義される. 突発性心停止 心拍再開時と同じ事象を描写している。心停止と死亡の区別は、大部分が対応の速さと質によって決まるため、両者は別個の現象というよりも、異なる転帰をとる単一の臨床的実体として捉えるのが最も妥当である。1].

このレビューは、おおむね35歳未満の人々を対象としています。年齢の境界線は恣意的なものではありません。それを超えると、冠動脈 動脈硬化 漸進的に病因像の主座を占めるようになり、臨床的問題は成人のそれへと収れんしていく 虚血性心疾患. その下位分類では、原因は主に遺伝性、先天性、または後天性の非動脈硬化性疾患であり、それに応じて診断や予防のアプローチも異なります。.

最も研究されている集団が競技アスリートであるのには、3つの理由がある。すなわち、組織的に集計されていること、データを生成する医学的評価を受けていること、そしてその死亡が報告されることである。これにより、大きな調査上の非対称性が生じている。非アスリートの若者における突然死は絶対数としてはより一般的であるものの、特徴付けははるかに進んでおらず、以下の記述の多くはアスリートのコホートから得られたものであり、定量化されていない精度をもって一般的な若い集団に適用されるものである。.

2. 疫学

2.1 発生率と測定の問題

歴史的発生率の推定値は、それらを体系的に過小評価させる方法論的限界、すなわちメディア報道や自主的登録への依存、明確な集団(コーホート)ではなく参加者数の推定値から導き出された不正確な母数、幅広く不均一な年齢層、労作性と非労作性の事象の区別の欠如によって損なわれていた [2,3].

全米大学体育協会(NCAA)の選手を対象とした20年間にわたる複数データベースを用いたサーベイランス研究は、これらの限界の大部分を克服している。2002年から2022年までの9,106,516選手・年を対象とし、4つの独立した症例確認戦略を用いて、総死亡数1,102件のうち、判定された心臓突然死(SCD)143件が特定された [4,5]. No single source captured more than 82% of cases — a finding that helps explain why earlier single-source estimates were low.

The resulting overall incidence was 1 per 63,682 athlete-years (95% CI 1:54,065–1:75,010) [4].

For comparison, Denmark, where SCD reporting in athletes is mandatory, reports an annual incidence of approximately 1.2 per 100,000 among competitive athletes for events occurring during or within one hour of exertion. Differences in case definition, exertional attribution, and population make direct comparison across national datasets unreliable, and apparent discrepancies between series more often reflect ascertainment methodology than true differences in risk.

2.2 Risk stratification by sex, race, and sport

Risk is not distributed evenly. The NCAA surveillance data demonstrate substantial and consistent gradients.

Table 1. Incidence of sudden cardiac death by demographic and athletic stratum, NCAA athletes, 2002–2022 [4]

Stratum Incidence (per athlete-year) 95% CI 4-year career risk Ratio vs. overall
Division I men’s basketball, White 1:5,848 1:2,498–1:13,691 ~1:1,462 10.9
Division I men’s basketball, Black 1:7,696 wide, overlapping ~1:1,924 8.3
Division I men’s basketball, overall 1:8,188 ~1:2,047 7.8
Basketball, all divisions 1:19,164 ~1:4,791 3.3
American-style football, all divisions 1:31,743 ~1:7,936 2.0
All Black athletes 1:26,704 1:20,417–1:34,925 ~1:6,676 2.4
All male athletes 1:43,348 1:36,228–1:51,867 ~1:10,837 1.5
All White athletes 1:74,581 1:60,247–1:92,326 ~1:18,645 0.85
All female athletes 1:164,504 1:110,552–1:244,787 ~1:41,126 0.39
Overall cohort 1:63,682 1:54,065–1:75,010 ~1:15,921 1.00 (reference)

Career risk is the simple four-fold annualized approximation used in the source publication [4].

Sex. Male athletes experience approximately 3.8 times the incidence of female athletes (commonly rounded to fourfold in secondary sources) [4]. The explanation is incompletely established but likely multifactorial: greater left ventricular mass and wall thickness for a given body size, differences in autonomic response and repolarization, higher prevalence of some arrhythmogenic substrates, and differences in the intensity and type of athletic exposure [6]. Notably, the sex difference is smaller for the channelopathies — particularly long QT syndrome, where female sex is a 危険因子 for events after puberty — than for the structural cardiomyopathies.

Race. Black athletes experience approximately 2.8 times the incidence of White athletes [4]. This finding requires careful interpretation. Race in this literature is a social variable functioning as an imperfect proxy for a mixture of unmeasured factors: differential participation by sport and position, body size, hypertension prevalence, sickle cell trait, socioeconomic access to care, structural determinants of health, and possibly ancestry-associated cardiac phenotypes. Contemporary guidance explicitly frames race as a sociopolitical construct in this context and calls for the capture of social determinants of health in future research [1]. The practical implication is that “Black race” identifies elevated risk without explaining it, and is a poor foundation for clinical algorithms.

Sport. Basketball carries the highest risk of any studied discipline, and does so independently: after multivariable adjustment for sex and race, basketball participation remains associated with elevated risk (odds ratio 2.75, 95% CI 1.73–4.34) [4]. American-style football contributes the largest absolute number of cases by virtue of roster size. Soccer is likewise identified among the higher-incidence disciplines. The common features of these sports — high-dynamic, stop-start exertion with repeated maximal efforts and abrupt autonomic transitions — are plausibly mechanistic rather than incidental, though the hypothesis has not been directly tested [7,8].

One frequently repeated error deserves correction. Within Division I men’s basketball, the point estimate for White players (1:5,848) exceeded that for Black players (1:7,696) [4]. Secondary sources commonly invert this. Both estimates rest on very small event counts with wide, overlapping confidence intervals, and the ordering within basketball should not be treated as established in either direction.

2.3 Temporal trend

SCD incidence among NCAA athletes declined by approximately 29% per five-year interval across the study period (five-year incidence rate ratio 0.71, 95% CI 0.61–0.82), while non-cardiovascular mortality in the same population remained unchanged (IRR 0.98, 95% CI 0.94–1.04) [4].

The specificity of the decline to cardiovascular death is suggestive, but the study was not designed to identify a mechanism and its authors decline to attribute the trend to any single intervention. Plausible contributors include broader ECG use at well-resourced programs, improved emergency action planning and automated external defibrillator deployment, better recognition of exertional warning symptoms, and secular changes in ascertainment. Disentangling these remains an open problem, and the trend should not be cited as evidence for the efficacy of any particular preventive strategy.

3. Etiology: The Spectrum of Disease

3.1 Distribution of causes

Among the 118 of 143 NCAA cases with sufficient information for 判決 [4]:

  • Autopsy-negative sudden unexplained death (AN-SUD): 19.5%
  • Idiopathic left ventricular hypertrophy or possible 心筋症: 16.9%
  • Hypertrophic cardiomyopathy: 12.7%
  • Remainder: congenital coronary 動脈 anomalies, arrhythmogenic cardiomyopathy, myocarditis, aortic dissection, and other causes

This distribution differs materially from the historical picture, in which hypertrophic cardiomyopathy was described as the single dominant cause [2,3]. The shift reflects improved forensic rigor rather than a change in disease biology: standardized expert adjudication reclassifies as idiopathic or unexplained many cases that less systematic review attributed to HCM on the basis of borderline wall thickness alone.

Across the broader literature, the proportion of cases in which autopsy fails to identify a structural cause ranges from approximately 10% to 42%, with variation driven by the thoroughness of the examination, the expertise of the pathologist, and whether cardiac-specific protocols were followed.

The implication for prevention is direct and underappreciated: in these data the largest single adjudicated category is the absence of a structural finding. Strategies focused exclusively on structural disease therefore leave a substantial proportion of events unexplained or undetected. This proportion is not fixed — it varies with forensic methodology, the expertise of the examining pathologist, and whether 分子解剖 is performed — but the importance of nonstructural and autopsy-negative causes is consistent across series.

3.2 Why exertion triggers events

Sudden death during exercise is best understood through the substrate–trigger–modulator framework. A vulnerable substrate — an anatomical, structural, or ion-channel abnormality — is necessary but rarely sufficient. Exercise supplies triggers and modulators that convert latent vulnerability into ventricular fibrillation [7,8].

Catecholaminergic surge. Exercise produces marked sympathetic activation with circulating catecholamines rising several-fold. Beta-adrenergic stimulation shortens refractoriness heterogeneously across the myocardium, increases automaticity, and enhances calcium loading of the sarcoplasmic reticulum. In conditions of abnormal calcium handling — catecholaminergic polymorphic ventricular tachycardia most explicitly — this is directly arrhythmogenic [8].

Demand ischemia. In anomalous coronary anatomy, myocardial bridging, or severe left ventricular outflow obstruction, exertional increases in myocardial oxygen demand are not matched by supply. Ischemia in turn produces regional conduction slowing and dispersion of repolarization, the substrate for reentry.

Mechanical and hemodynamic stress. Increased wall stress, chamber dilation, and vigorous contraction against an obstruction stretch myocardium acutely. Mechanoelectric feedback — stretch-activated ion channels altering membrane potential — provides a plausible mechanism linking mechanical load to electrical instability, and may be relevant in arrhythmogenic cardiomyopathy, where exercise appears to accelerate disease as well as trigger events.

Electrolyte and acid–base shifts. Exercise produces potassium efflux from working muscle, intracellular acidosis, volume depletion, and in prolonged effort hyponatremia. Each alters conduction and repolarization [9].

Autonomic transition. The abrupt withdrawal of sympathetic tone and surge of vagal activity at cessation of effort produces a period of electrical heterogeneity. A meaningful proportion of exertion-related events occur immediately after exercise rather than during it, and the stop-start structure of basketball, soccer, and football may repeatedly reproduce these transitions [8].

Substrate progression. In some conditions exercise is not merely a trigger but a driver of disease. This is best established for arrhythmogenic cardiomyopathy caused by plakophilin-2 variants, where endurance exercise volume is associated with earlier phenotypic expression, higher arrhythmic burden, and structural progression [1,10].

3.3 The cardiomyopathies

Hypertrophic cardiomyopathy. Defined by unexplained left ventricular hypertrophy, typically with an inherited sarcomeric basis, though approximately half of patients have no identifiable causal variant. Phenotype, clinical course, and arrhythmic risk vary widely. Mechanisms of sudden death include ventricular arrhythmia arising from myocyte disarray and interstitial fibrosis, ischemia from microvascular dysfunction, and hemodynamic collapse from dynamic outflow obstruction. Risk stratification incorporates maximal wall thickness, 家族の歴史 of sudden death, unexplained syncope, non-sustained ventricular tachycardia, left atrial size, outflow gradient, apical aneurysm, and extent of late gadolinium enhancement on cardiac magnetic resonance. Individuals who carry a pathogenic variant without a hypertrophic phenotype have low arrhythmic risk [1].

Arrhythmogenic cardiomyopathy. Characterized by ventricular dysfunction — right, left, or biventricular — with a burden of ventricular arrhythmia disproportionate to the degree of chamber dilation or systolic impairment. Most identified variants affect desmosomal proteins, plakophilin-2 being the most common, though roughly half of cases are genotype-negative. Genotype substantially modifies risk: plakophilin-2-mediated disease shows clear exercise-associated acceleration and elevated arrhythmic risk with endurance participation, whereas evidence for comparable risk in non-plakophilin-2 and genotype-negative disease is not established [10]. Distinguishing early arrhythmogenic cardiomyopathy from the right ventricular dilation of endurance-trained athletes is among the most difficult problems in sports cardiology [1].

Dilated cardiomyopathy. Left ventricular or biventricular dilation with systolic dysfunction, with roughly 60% genotype-negative. Arrhythmic risk rises with lower ejection fraction, symptoms, and scar burden, and is disproportionately high in specific genetic subtypes — lamin A/C, desmoplakin, and filamin C — which warrant closer surveillance regardless of ejection fraction. Preliminary evidence suggests higher cumulative lifetime exercise exposure is associated with lower ejection fraction in lamin A/C-associated disease, raising the possibility that exercise contributes to progression as well as to arrhythmic triggering [1].

Left ventricular hypertrabeculation. Prominent trabeculae with deep intertrabecular recesses, formerly termed left ventricular noncompaction. It is no longer considered a distinct cardiomyopathy. In the absence of coexisting hypertrophic or dilated phenotype, ventricular arrhythmia, or symptoms, adverse events have not been demonstrated, and isolated hypertrabeculation in an asymptomatic person is best regarded as a morphological variant [1].

3.4 The channelopathies

Inherited arrhythmia syndromes can produce sudden death in a structurally normal heart and are an important identifiable cause of autopsy-negative sudden death.

Long QT syndrome. Delayed ventricular repolarization predisposing to torsades de pointes. Genotype predicts trigger: LQT1 (KCNQ1) events are characteristically exertional, with swimming a distinctive trigger; LQT2 (KCNH2) events associate with auditory startle, emotion, and the postpartum period; LQT3 (SCN5A) events occur predominantly at rest or during sleep. Diagnosis rests on corrected QT interval, symptom history, family history, and genetic testing. Two caveats are clinically important: QTc thresholds in athletes differ from those in the general population, and the QT interval may normalize intermittently, so that a single normal resting QTc does not exclude the diagnosis. Concealed long QT syndrome — genotype-positive with a persistently normal QTc — occurs in a substantial minority of variant carriers [1].

Catecholaminergic polymorphic ventricular tachycardia. Caused most often by ryanodine receptor (RYR2) variants producing abnormal diastolic calcium release under adrenergic stress. It is the チャネル病 most specifically tied to exertion, characteristically producing bidirectional or polymorphic ventricular tachycardia at reproducible heart-rate thresholds during exercise. The resting ECG is typically normal, which places this condition beyond the reach of resting ECG screening. Exercise testing has high diagnostic yield where CPVT is clinically suspected, characteristically reproducing the arrhythmia at a consistent heart-rate threshold, and is the appropriate test in a person with exertional syncope and a normal resting ECG [1].

Brugada syndrome. Characterized by coved ST elevation in the right precordial leads, associated with SCN5A variants in a minority of cases. Events occur predominantly at rest, during sleep, or with fever rather than during exertion, though fever accompanying exercise is a recognized precipitant [1].

Wolff-Parkinson-White pattern. An accessory atrioventricular pathway. Sudden death occurs when 心房細動 conducts rapidly over a pathway with a short refractory period, degenerating into ventricular fibrillation. Unlike most causes discussed here, this is a readily detectable and definitively treatable condition, and the resting ECG is diagnostic [1].

3.5 Congenital coronary artery anomalies

Anomalous aortic origin of a coronary artery is among the leading causes of exertional sudden death and among the least detectable by conventional screening.

The highest-risk variant is anomalous origin of the left coronary artery from the right sinus with an interarterial course between the aorta and pulmonary artery. Proposed high-risk features include an intramural segment within the aortic wall, a slit-like proximal orifice, an acute take-off angle, and greater intramural length. The mechanism is thought to involve dynamic compression and orifice distortion during exertion as the great vessels expand, producing intermittent ischemia that may leave no fixed abnormality between episodes [1].

Anomalous right coronary origin with an interarterial course is more common and carries lower risk; many affected individuals remain asymptomatic. Other variants — intraseptal, retroaortic, prepulmonic courses — are generally benign.

The clinical challenge is that affected individuals are frequently asymptomatic until the index event, resting ECG is typically normal, and exercise stress testing may fail to provoke ischemia even in high-risk anatomy. Definitive diagnosis requires anatomical imaging, most often coronary computed tomographic angiography or cardiac magnetic resonance [1].

Myocardial bridging, in which a coronary segment tunnels through myocardium, is common and usually incidental. It becomes clinically relevant only where deep or long tunneled segments produce demonstrable ischemia [1].

3.6 Myocarditis and acquired conditions

Myocarditis produces sudden death through arrhythmia arising from acute 炎症, edema, and subsequent fibrosis. Its importance lies partly in being potentially transient: vigorous exercise during active myocardial inflammation is arrhythmogenic, but risk substantially resolves with the inflammation. This underlies the standard recommendation to abstain from exertion until symptoms and objective evidence of inflammation have resolved. Emerging cardiac magnetic resonance data suggest that selected athletes may safely return earlier than the three-to-six-month interval assumed by earlier guidance, although the evidence base remains limited and return should be governed by objective resolution of inflammation rather than by elapsed time alone [1,11].

Aortopathy. Marfan syndrome, Loeys-Dietz syndrome, vascular Ehlers-Danlos syndrome, and bicuspid aortic valve-associated aortopathy predispose to acute aortic dissection. This is a rare cause of sudden death in the young but distinctive in being detectable by physical examination and imaging, and in that risk relates to aortic dimension in a way that permits threshold-based management. Marked aortic enlargement is rare in young athletes — diameters above 42 mm in males and 40 mm in females are unusual regardless of body size — so such a finding warrants evaluation for an underlying aortopathy rather than attribution to training [1].

Arrhythmic mitral valve prolapse. Most mitral valve prolapse is benign, but a subset — characteristically bileaflet prolapse with mitral annular disjunction, inferolateral late gadolinium enhancement, and complex ventricular ectopy — is associated with sudden death. Papillary muscle traction and consequent regional fibrosis provide a plausible arrhythmic substrate [1].

Commotio cordis. Ventricular fibrillation induced by blunt precordial impact during the vulnerable phase of repolarization, in a structurally normal heart. It is a mechanical rather than a disease phenomenon, is unaffected by any screening strategy, and is survivable with immediate defibrillation [1].

Sickle cell trait. Associated with exertional collapse and death, particularly during intense conditioning in heat, through mechanisms involving exertional rhabdomyolysis and metabolic derangement rather than primary arrhythmia. It is included here because it presents as sudden collapse during exertion and is relevant to differential diagnosis and to prevention protocols [1].

3.7 Genetic architecture: penetrance, modifiers, and the limits of genotype

Most of the conditions described above are inherited, but inheritance in this field behaves far less deterministically than the term “genetic heart disease” suggests, and the gap between genotype and outcome is where much of the clinical difficulty lies.

Incomplete penetrance and variable expressivity. Carrying a pathogenic variant does not reliably produce disease, and where it does, severity varies widely within families sharing an identical variant. Penetrance estimates derived from clinically ascertained families — identified because someone was affected — substantially overstate risk when applied to variants found incidentally or through population screening. Estimates from unselected cohorts are consistently lower. This has direct consequences: an individual who is genotype-positive and phenotype-negative for hypertrophic cardiomyopathy carries low arrhythmic risk and is treated very differently from one with an expressed phenotype [1].

Age-dependent expression. Phenotype in hypertrophic, arrhythmogenic, and dilated cardiomyopathy typically emerges over adolescence and early adulthood rather than being present from birth. A normal evaluation at 14 does not exclude disease at 24. This underlies the requirement for serial evaluation of genotype-positive relatives rather than single-timepoint clearance, and it explains why screening cohorts followed long enough eventually record deaths in individuals who screened normal.

Modifier genes and polygenic background. The same variant produces different phenotypes in different genetic backgrounds. Common variants of individually small effect, aggregated as polygenic scores, appear to modify penetrance and severity in the cardiomyopathies — potentially explaining part of the within-family variability that monogenic models cannot. This work is at an earlier stage than the equivalent literature in coronary disease, and polygenic scores are not yet clinically actionable in this setting, but the direction is toward a model in which a rare pathogenic variant sets susceptibility and common variation, environment, and training load determine whether and when disease appears.

Genotype-negative disease. Roughly half of hypertrophic and arrhythmogenic cardiomyopathy cases and approximately 60% of dilated cardiomyopathy cases have no identifiable causal variant. A negative genetic test in an affected individual does not exclude an inherited condition, and does not obviate clinical screening of relatives.

Variants of uncertain significance. These are the most common result of broad panel testing in the absence of a clear phenotype, and they are frequently misinterpreted as intermediate-risk findings. They are not: they are uninformative pending reclassification, which may occur in either direction as evidence accumulates. Testing in individuals without phenotype or family history predominantly generates them, which is the principal argument against genetic testing as a primary screening tool [1].

3.8 Autopsy-negative sudden unexplained death and molecular autopsy

When comprehensive autopsy including toxicology and histology identifies no cause, the death is classified as autopsy-negative sudden unexplained death — or, in some series, sudden arrhythmic death syndrome. This classification is provisional rather than terminal.

Postmortem genetic testing identifies a clinically actionable pathogenic or likely pathogenic variant in a meaningful minority of these cases. Applying contemporary ACMG classification criteria to 302 expertly adjudicated cases, an actionable variant was identified in 13% of decedents, predominantly catecholaminergic polymorphic ventricular tachycardia and long QT syndrome, with RYR2 the most implicated gene [12]. A clinically relevant diagnosis was established in a substantially larger proportion of families when postmortem 遺伝学 was combined with clinical evaluation of surviving relatives.

Reported yields vary widely across series — from under 4% to approximately 30% — and depend heavily on the variant-classification framework applied. Series adhering strictly to ACMG criteria report lower yields; those using looser thresholds report higher ones, largely by counting variants of uncertain significance as diagnostic. Cross-series comparison is therefore unreliable unless classification criteria are matched [12].

Three points follow. First, the proportion of truly unexplained deaths is lower than autopsy-negative rates suggest. Second, molecular autopsy requires appropriate specimen retention, which depends on medical examiner practice and is frequently not performed. Third, and most important clinically, a diagnosis in the decedent enables cascade screening of living relatives — making postmortem evaluation a prevention strategy for the family, not merely a determination of cause.

4. The Athlete’s Heart: Adaptation Versus Disease

Sustained training produces cardiac remodeling that overlaps phenotypically with the diseases described above. Distinguishing adaptation from pathology is the central diagnostic problem in this field, and misclassification carries costs in both directions.

4.1 Structural adaptation

Endurance training produces predominantly 偏心リモデリング — chamber enlargement with proportionate wall thickening — driven by sustained volume loading. Strength training produces relatively more concentric change. Most athletes exhibit a mixed pattern reflecting the actual demands of their sport.

Adaptation is modified by sport, sex, body size, ethnicity, and training duration. Left ventricular wall thickness in the 13–15 mm range in men, and right ventricular dilation in endurance athletes, fall into diagnostic gray zones overlapping hypertrophic and arrhythmogenic cardiomyopathy respectively. Left ventricular end-diastolic dimensions of 60 mm or more occur in a meaningful minority of trained athletes without valvular or myocardial disease [1,11].

Features favoring physiological adaptation include symmetric enlargement of all four chambers, normal or supranormal diastolic function, absence of late gadolinium enhancement, normal functional capacity, appropriate 血圧 response to exercise, and regression with detraining. Features favoring pathology include asymmetric hypertrophy, impaired diastolic function, late gadolinium enhancement, a family history of cardiomyopathy or premature sudden death, and marked ECG abnormality out of proportion to the structural findings [1].

4.2 Electrical adaptation

Training produces a reproducible set of ECG changes: sinus bradycardia and sinus arrhythmia from increased 迷走神経トーン, ectopic atrial and junctional rhythms, first-degree and Mobitz type I atrioventricular block, incomplete right bundle branch block, isolated voltage criteria for ventricular hypertrophy, and early repolarization. These are physiological, require no evaluation in an asymptomatic person without concerning family history, and their misclassification as pathological was the principal historical barrier to ECG-based screening [13].

Remodeling and repolarization vary by ethnicity, not only between Black and White athletes. Athletes of African and Afro-Caribbean descent show greater left ventricular wall thickness for a given body size and a distinctive repolarization pattern — J-point elevation with convex ST-segment elevation followed by T-wave inversion confined to leads V1–V4 — which is benign. Applying criteria derived from White European cohorts without this accommodation more than doubles the false-positive rate in Black athletes [14]. Distinct patterns have also been described in athletes of Middle Eastern, South Asian, and East Asian descent, and normative data for these groups remain comparatively sparse — a gap that propagates directly into screening performance wherever population-specific reference values do not exist.

Age matters similarly: T-wave inversion in leads V1–V3 in athletes aged 16 or younger represents a persistent juvenile pattern rather than disease [13].

5. Clinical Presentation and Warning Symptoms

The defining clinical feature of these conditions is that most affected individuals are asymptomatic until the index event. Where symptoms do occur, they are frequently attributed to deconditioning, dehydration, anxiety, or normal exertional limitation — by the individual, by coaching staff, and often by clinicians.

Symptoms warranting evaluation before further participation:

Exertional syncope or near-syncope. The single most important warning symptom. Syncope during exertion, as distinct from immediately after cessation, should be presumed cardiac until proven otherwise. Post-exertional syncope is more often neurally mediated but does not exclude cardiac causes.

Exertional chest pain. Particularly if reproducible at a consistent workload, suggesting demand ischemia from anomalous coronary anatomy or outflow obstruction.

Exertional dyspnea disproportionate to conditioning, especially where it represents a change from established baseline capacity.

Palpitations with exertion, particularly abrupt in onset and offset, or associated with lightheadedness.

Unexplained decline in performance not attributable to training load, illness, or injury.

The family history is as informative as the personal history: premature sudden death before age 50 in a 一親等血族, known inherited cardiomyopathy or arrhythmia syndrome, unexplained drowning, single-vehicle accidents without explanation, or unexplained seizure disorder — the last because long QT syndrome and CPVT events are frequently misdiagnosed as epilepsy [1,15].

6. Diagnostic Evaluation

6.1 Electrocardiography and the evolution of interpretation criteria

The resting 12-lead ECG detects the electrical signatures of cardiomyopathy and channelopathy, and is the single most informative low-cost test in this population. Its historical limitation was not sensitivity but specificity: applying general-population criteria to trained athletes generated false-positive rates that made systematic use impractical.

Interpretation criteria have been refined substantially over fifteen years.

Table 2. Evolution of athlete ECG interpretation criteria

Criteria set Year False positives, White athletes False positives, Black athletes Principal change
ESC recommendations [16] 2010 16.2% 40.4% Training-related versus unrelated dichotomy; no ethnicity-specific criteria; most T-wave inversion classified abnormal
Seattle Criteria [17] 2013 7.1% 18.4% Black athlete repolarization pattern recognized as physiological; QTc thresholds raised to ≥470 ms (male) and ≥480 ms (female)
Refined Criteria [14] 2014 5.3% 11.5% Isolated axis deviation and isolated atrial enlargement reclassified as non-triggering
International Criteria [13] 2017 ~1.3–3.0% ~4.2–6.8% Formal normal/borderline/abnormal categories; two or more borderline findings required to trigger evaluation

The 2017 International Criteria define exactly five borderline findings: left axis deviation, right axis deviation, left atrial enlargement, right atrial enlargement, and complete right bundle branch block [13]. Any single one of these in isolation does not warrant evaluation in an asymptomatic athlete without concerning family history; two or more do. Isolated voltage criteria for left or right ventricular hypertrophy are classified as normal, not borderline — a point frequently misstated.

Two caveats matter. First, the reported false-positive rates derive from expert or specialist-supervised interpretation; rates under non-specialist reading are consistently higher, and the magnitude of that gap has not been established at scale. Second, gains in specificity have not been free: in masters and pediatric cohorts, the International Criteria have missed diagnoses that earlier criteria would have flagged, including dilated cardiomyopathy presenting with isolated left axis deviation.

6.2 Diagnostic versus screening sensitivity

An important distinction is frequently elided. Diagnostic sensitivity is the probability that a person with established, fully expressed disease has an abnormal ECG. Screening sensitivity is the probability that an asymptomatic adolescent with early, incomplete, or concealed expression is correctly identified in a mass-screening setting.

The second is systematically lower than the first. Adolescent phenotype is often immature — both hypertrophic and arrhythmogenic cardiomyopathy express progressively — dynamic conditions are intermittently normal at rest, and field acquisition and interpretation conditions are inferior to those of a referral laboratory. Sensitivity figures quoted from referral cohorts of patients with known disease, commonly cited near 98% for hypertrophic cardiomyopathy, should not be presented as screening performance [18].

The most instructive evidence comes from long-term follow-up of a screened cohort. Among 11,168 adolescent English Football Association players screened with questionnaire, examination, ECG, and echocardiography, conditions associated with sudden death were identified in 0.38%, with ECG abnormal in 86% of those individuals versus 7% for history and 5% for physical examination [19]. Over a mean 10.6 years of follow-up, however, eight athletes died of cardiac causes — six of whom had screened normal at age 16, at a mean of 6.8 years after screening, most from cardiomyopathies not detectable at the time of testing.

A normal screen is not durable clearance. This is a property of progressive disease, not a failure of the test.

6.3 Secondary evaluation

An abnormal primary screen or concerning symptom initiates further testing, selected by the suspected condition rather than applied as a fixed panel.

Transthoracic echocardiography assesses wall thickness, chamber dimensions, systolic and diastolic function, valvular structure, aortic dimensions, and in many cases coronary origins.

Cardiac magnetic resonance provides superior tissue characterization. Late gadolinium enhancement identifies fibrosis and scar; T2-weighted imaging and parametric mapping identify edema and active inflammation. It is often decisive in distinguishing physiological hypertrophy from cardiomyopathy, in evaluating the right ventricle for arrhythmogenic cardiomyopathy, and in diagnosing myocarditis. Late gadolinium enhancement confined to right ventricular insertion points is a recognized finding without established adverse prognostic significance.

Exercise testing should be sport-specific and designed to provoke symptoms at the intensity actually encountered in competition, rather than terminated at arbitrary heart-rate targets or performed pharmacologically. It is essential in suspected CPVT, in evaluating ventricular ectopy, and in assessing ischemia in anomalous coronary anatomy.

Ambulatory rhythm monitoring characterizes arrhythmia burden and its relationship to activity; extended monitoring is often required given the intermittency of clinically relevant events.

Coronary imaging by CT angiography or magnetic resonance is required to define coronary origin and course when anomalous anatomy is suspected.

Genetic testing confirms diagnosis where the phenotype is established, informs risk stratification in specific conditions — plakophilin-2 in arrhythmogenic cardiomyopathy, lamin A/C in dilated cardiomyopathy, genotype in long QT syndrome — and enables cascade screening of relatives. It performs poorly as a primary diagnostic test in the absence of phenotype or family history, where it principally generates variants of uncertain significance.

Notably, cardiac imaging, exercise testing, and ambulatory monitoring have insufficient evidence to support their use as primary screening tools in asymptomatic individuals [1]. Their role is in secondary evaluation.

6.4 Emerging technologies

Artificial intelligence applied to the ECG. Deep learning models trained on large ECG corpora can identify conditions that lack a pathognomonic signature to the human eye. Convolutional neural networks have been developed to detect hypertrophic cardiomyopathy from the 12-lead ECG alone, with performance maintained on external validation across diverse international cohorts and in pediatric and adolescent populations [20]. Comparable models identify electrocardiographically concealed long QT syndrome — genotype-positive individuals with a normal measured QTc — which conventional interval measurement cannot detect by definition [21].

The potential relevance to this field is obvious: the principal limitation of ECG screening is not cost but interpretive accuracy, and an algorithm that improves specificity without sacrificing sensitivity would change the calculus directly. Several important caveats apply. Models trained predominantly on clinical populations may perform differently in trained athletes, whose baseline ECGs differ systematically from those of the general population, and athlete-specific validation remains limited. Performance in the demographic groups with the highest false-positive rates under conventional criteria has not been separately established. And an algorithm that flags disease without an accessible pathway to secondary evaluation reproduces the equity problem described in Section 7.5 rather than solving it. AI-ECG is best understood at present as a promising adjunct under active validation rather than an established screening tool.

Wearable and consumer devices. Smartwatches, adhesive patch monitors, and consumer single-lead and multi-lead ECG devices are now widely used by athletes, and increasingly generate cardiac data that reaches clinicians unsolicited. Their genuine strengths are duration and opportunism: a patch monitor worn for two weeks or a smartwatch worn continuously may capture a symptomatic paroxysmal arrhythmia that a resting ECG and a 24-hour Holter both miss, and this is a real diagnostic contribution in a person with intermittent palpitations.

Their limitations are equally clear. Single-lead recordings cannot assess axis, chamber enlargement, repolarization across the precordium, or most of the criteria on which athlete ECG interpretation depends. Automated rhythm classification is optimized for atrial fibrillation detection in older populations and performs poorly for the arrhythmias relevant here. Signal quality during exercise — precisely when it would be most valuable — is frequently inadequate. And the false-positive burden generated by consumer devices in young, healthy, highly motivated users is substantial and largely unquantified.

Wearables complement rather than replace structured evaluation. A consumer device recording during a symptomatic episode is valuable evidence; a normal consumer recording is not clearance, and should not be treated as one by the athlete or the clinician.

7. Screening: What It Achieves and What It Does Not

Screening is one component of prevention. This section assesses it on its own terms rather than treating it as the organizing question of the field.

7.1 The rationale and its limits

Preparticipation cardiovascular screening aims to identify people with unrecognized disease in time for management that reduces risk. Its effectiveness depends on a chain of conditions: the disease must be detectable before the event, the test must detect it at acceptable cost and false-positive burden, effective management must exist, and affected individuals must have access to it.

That chain has weak links. Resting ECG has very limited sensitivity for anomalous coronary origin, catecholaminergic polymorphic ventricular tachycardia, early or concealed arrhythmogenic cardiomyopathy, aortopathy, and significant valve disease, and by definition contributes nothing in cases that prove autopsy-negative — the largest single category. Screening addresses a subset of the problem.

7.2 Comparative performance of screening components

Meta-analytic estimates in athletic populations give ECG a sensitivity approaching 90–94% for conditions detectable by ECG, with specificity near 93%, against approximately 20% sensitivity for history and 9% for physical examination [18]. Evidence drawn specifically from NCAA populations has since been synthesized separately [22]. The qualifier matters: this figure describes performance against cardiomyopathies and channelopathies with electrical signatures, not against the full spectrum of causes, and should not be read as 94% sensitivity for sudden death risk overall. Contemporary guidance cites a comparable range, placing history and physical sensitivity for silent cardiac conditions at 10–20% and noting that adding ECG raises the sensitivity of the preparticipation evaluation to approximately 94% [1].

The argument for ECG is therefore not that it performs well in absolute terms; it is that history and physical examination alone detect only a minority of relevant conditions. This is not an argument against the history and physical examination, which identifies symptomatic individuals, elicits family history, and detects Marfan stigmata, pathological murmurs, diminished femoral pulses, and hypertension — none of which an ECG reliably captures.

7.3 Guideline positions

European guidance has long recommended ECG-inclusive screening [11,16]. North American guidance historically endorsed a standardized 14-point history and physical examination without recommending universal ECG [15].

That divide has narrowed substantially. The 2025 American Heart Association / American College of Cardiology scientific statement holds that inclusion of a resting 12-lead ECG is reasonable, because it improves detection of underlying cardiac conditions in asymptomatic athletes relative to history and physical examination alone. The endorsement carries three conditions: clinicians must be adequately trained in contemporary athlete-specific interpretation criteria; programs must ensure access to secondary evaluation, including the financial and logistical resources for systematic downstream assessment; and because no approach provides absolute protection, an 緊急時対応計画 must be in place wherever people train and compete [1].

The unresolved questions are therefore not whether ECG may be used, but whether it should be universally implemented, how programs should be resourced to use it safely, and whether incremental benefit justifies downstream cost and harm.

7.4 Health economics

Published cost-effectiveness estimates for adding ECG to 事前スクリーニング span a wide range, driven more by assumption choice than by data.

Table 3. Published economic evaluations of ECG-inclusive screening

Analysis Comparison Result
Wheeler et al. (2010) [23] ECG + H&P vs. H&P alone $42,900 per life-year saved (95% CI $21,200–$71,300)
Wheeler et al. (2010) [23] ECG + H&P vs. no screening $76,100 per life-year saved ($62,400–$130,000)
Schoenbaum et al. (2012) [24] H&P then ECG vs. H&P alone $68,800 per QALY
Schoenbaum et al. (2012) [24] ECG alone vs. H&P alone $37,700 per QALY
Halkin et al. (2012) [25] National program, US extrapolation $10.6–14.4 million per life saved

Two of the three principal analyses return figures within commonly cited US willingness-to-pay thresholds. The third, returning figures orders of magnitude higher, does so partly by loading recurring annual history and physical costs into the ECG arm — an accounting choice contested in subsequent literature [25].

Every one of these analyses is governed by a single assumption: the relative risk reduction conferred by detection and subsequent management. That parameter is not well established, and as discussed in Section 8 the evidence underlying it has shifted.

7.5 Equity

Screening programs can widen the inequities they are intended to reduce. The mechanism is the secondary evaluation, not the primary screen.

An abnormal screening result initiates a diagnostic cascade — echocardiography, cardiac magnetic resonance, ambulatory monitoring, genetic evaluation, subspecialty consultation — that in unassisted settings the family must fund. Uninsured and underinsured individuals face two consequences: they may exit the pathway without completing evaluation, continuing to participate with uncharacterized risk; and their absence from outcome data systematically biases estimates of disease prevalence, specificity, and cost-effectiveness in a favorable direction.

This is compounded by the ethnic disparity in false-positive rates. Even under contemporary criteria, false-positive findings remain more frequent among Black athletes [14], meaning that the population most likely to be referred for costly secondary evaluation overlaps with the population least likely to be able to afford it. Contemporary guidance states directly that screening programs without appropriate downstream resources have the potential to harm athletes from underrepresented racial and ethnic groups [1].

A screening program without a funded pathway to secondary evaluation is not a neutral intervention. It is a mechanism for identifying risk in people who cannot then act on it.

7.6 Psychological consequences

Screening programs are evaluated almost exclusively on detection and cost. The psychological consequences are real, are borne disproportionately by people who turn out not to have disease, and are rarely measured.

The false-positive interval. Between an abnormal screening result and its resolution, an athlete is a person who has been told their heart may be dangerously abnormal. That interval is frequently weeks and sometimes months, determined by appointment availability, insurance authorization, and imaging capacity rather than by clinical urgency. Documented consequences include anxiety, intrusive thoughts about dying during exertion, sleep disruption, and withdrawal from training during a period in which no restriction has actually been imposed. Where the athlete’s identity is substantially organized around sport — as it is for many at collegiate and elite level — the threat is to selfhood as much as to health.

Resolution is incomplete. Reassurance after a negative workup does not reliably return people to baseline. Residual health anxiety, continued symptom vigilance, and reduced training intensity have been described persisting after formal clearance, a pattern familiar from other screening contexts. Because false positives outnumber true positives by a large factor at any plausible operating point, this is not a marginal harm affecting a handful of people; it is the modal experience of an abnormal screen.

True positives carry their own burden. A diagnosis in a young person may bring restriction or modification of participation, loss of athletic identity, disrupted scholarship or professional prospects, defibrillator carriage in adolescence, and the knowledge of inherited risk extending to siblings and future children. Depression and anxiety are recognized sequelae of disqualification, and the transition out of competitive sport is itself a period of elevated psychological risk independent of the cardiac diagnosis.

Implications. Three follow directly. Time from abnormal screen to definitive resolution is a clinically meaningful quality metric, not merely an operational one, and shortening it is a genuine intervention. Communication of an abnormal result should convey the base rate — that most abnormal screens resolve without disease — rather than deferring all interpretation to the specialist. And psychological support should be planned into screening programs rather than improvised, particularly for athletes who are restricted or who transition out of competition.

8. Management and Sports Participation

8.1 The shift from disqualification to shared decision-making

Historical practice restricted individuals with identified 心血管疾患 from competitive sport more or less categorically. That paradigm has been substantially abandoned, on both ethical and empirical grounds [1,11].

The empirical case rests on outcome data:

  • In a prospective multinational observational study of individuals with hypertrophic cardiomyopathy — 1,534 patients plus 126 genotype-positive, phenotype-negative individuals across 42 centers — those engaging in vigorous exercise, including competitive athletes, did not experience higher rates of death, resuscitated arrest, appropriate defibrillator shock, or arrhythmic syncope than moderate exercisers or sedentary participants [26].
  • A prospective multinational registry of athletes with implantable cardioverter-defibrillators found no deaths, resuscitated arrests, or arrhythmia-related injuries during sport over long-term follow-up [27].
  • Contemporary cohorts of elite athletes with genetic heart disease who returned to competition under expert supervision report low rates of breakthrough events [28].

The ethical case is that the historical model rested on the premise that athletes cannot make informed decisions about their own risk — a position that is neither supported by evidence nor consistent with the standards applied elsewhere in medicine.

Shared decision-making does not imply equal risk across conditions. It is a process for incorporating an individual’s values into a decision under uncertainty, not a conclusion that all diagnoses carry comparable danger or that all participation requests should be accommodated. The risk attached to genotype-positive, phenotype-negative status differs by orders of magnitude from that attached to plakophilin-2-mediated arrhythmogenic cardiomyopathy in an endurance athlete, and the framework is designed to make that difference explicit rather than to dissolve it.

The 2025 AHA/ACC statement is explicit that it does not issue disqualification recommendations, but rather clinical considerations to inform shared decision-making. Under this framework a uniform approach of restriction should not be applied to individuals with cardiomyopathy; participation is instead determined through a process incorporating accurate diagnosis, condition-specific risk stratification, guideline-directed treatment, disclosure of known and unknown risks, and the individual’s own values and risk tolerance. For those under 18, parents or guardians participate directly [1].

8.2 Where risk remains prohibitive

Shared decision-making does not mean that all participation is endorsed. Situations where risk is understood to outweigh benefit include arrhythmogenic cardiomyopathy caused by plakophilin-2 variants, particularly with endurance sport; active myocarditis or pericarditis; unrepaired anomalous origin of the left coronary artery with an interarterial course; severe symptomatic aortic stenosis; heritable thoracic aortic disease with aortic dilation; and prior aortic dissection. Participation is also generally deferred during diagnostic evaluation and until guideline-directed therapy is optimized [1].

8.3 Condition-specific management

Management is disease-specific and is the mechanism by which detection produces benefit: beta-blockade in long QT syndrome and CPVT, with flecainide and sympathetic denervation in selected CPVT cases; defibrillator implantation where risk stratification indicates, though never solely to enable sport participation; カテーテルアブレーション for accessory pathways and selected ventricular arrhythmias; surgical reimplantation or unroofing for high-risk coronary anomalies; septal reduction for obstructive hypertrophic cardiomyopathy; aortic surgery at guideline thresholds; and exercise prescription modification where disease progression is exercise-associated [1].

Two points deserve emphasis. First, individuals who discontinue competitive sport should be counseled on the established health benefits of continued recreational physical activity — a transition, not a cessation. Second, longitudinal surveillance is required regardless of the participation decision, because phenotype evolves and the original decision may require revisiting.

8.4 Return to play and longitudinal surveillance

A participation decision is a point on a trajectory rather than a conclusion, and the surveillance that follows is what makes continued participation defensible.

Serial imaging at intervals determined by condition and rate of change. Genotype-positive, phenotype-negative individuals in conditions where exercise may precipitate phenotypic conversion — plakophilin-2-mediated arrhythmogenic cardiomyopathy most clearly — warrant close longitudinal surveillance, with imaging intervals individualized to phenotype, exercise exposure, and evidence of disease progression, while continuing to compete [1]. Aortic dimensions in aortopathy are followed on a schedule set by absolute diameter and rate of growth, with side-by-side comparison of images rather than reliance on prior reports, since inter-study measurement variability can exceed true annual change.

Repeat exercise testing, sport-specific and to the intensity actually encountered in competition, to confirm continued absence of provoked arrhythmia or ischemia and to verify the efficacy of pharmacological suppression where it has been prescribed.

Ambulatory rhythm monitoring to track arrhythmia burden over time, and device interrogation where a defibrillator is present, including appropriate and inappropriate therapy history.

Structured re-evaluation of the decision itself. The shared decision-making conversation should be revisited periodically rather than treated as settled — because the evidence base is changing, because the individual’s own risk tolerance may change, and because phenotype progression may move a person from one risk category to another without symptoms.

Post-intervention return — after surgical coronary reimplantation, aortic repair, ablation, or device implantation — follows condition-specific intervals governed by healing, demonstrated absence of ischemia or inducible arrhythmia, and normal ventricular function, rather than by elapsed time alone.

9. Secondary Prevention: Emergency Response

Because no screening strategy detects all disease, and because some causes are undetectable in principle, survival in a substantial proportion of events is determined entirely by what happens in the first minutes.

9.1 Determinants of survival

Survival depends on rapid recognition, immediate high-quality chest compressions, and early defibrillation, and additionally on rhythm at collapse, underlying substrate, arrest location, emergency medical services interval, airway management, post-arrest care, and neurological injury.

Recognition is the most common failure point in athletic settings, and the one most amenable to training. Bystanders are primed to interpret the collapse of a young athlete as anything other than 心停止. Agonal breathing is mistaken for breathing; seizure-like activity, common in the first seconds of arrest, is mistaken for a primary neurological event. A venue with excellent defibrillator coverage can still lose several minutes to a delayed recognition decision — which is why time-to-first-compression should be measured and drilled separately from time-to-shock, since the two fail independently.

9.2 Emergency action plans

An adequate plan comprises a written, venue-specific document reviewed at least annually with local emergency medical services and physically accessible at each site; a designated coordinator responsible for oversight; defibrillator placement supporting a collapse-to-shock interval of three minutes or less from any point of athletic activity; documented CPR and defibrillator training among athletic trainers, coaching staff, and strength staff; rehearsal drills with time-to-first-compression and time-to-shock recorded; and a coordinated transport plan to a designated receiving facility [1].

Where such plans have been prospectively studied in high school settings, survival to hospital discharge has substantially exceeded rates observed for out-of-hospital cardiac arrest generally [29] — a difference attributable to witnessed collapse, trained responders, and immediate defibrillator availability rather than to any characteristic of the individuals.

A final observation on policy. Sudden cardiac arrest and death will continue to occur irrespective of screening strategy and participation decisions, and their occurrence should not be interpreted as evidence that a shared decision-making approach has failed. Sound policy is not well made in the immediate aftermath of an individual event.

10. Family Evaluation

A diagnosis of inherited heart disease is a diagnosis about a family. Where a proband is identified — living or deceased — first-degree relatives warrant clinical evaluation, and cascade genetic testing where a pathogenic variant has been identified [1].

This applies with particular force after an unexplained death. Postmortem specimen retention adequate for genetic analysis is not universal practice among medical examiners, and its absence forecloses the family’s diagnostic pathway permanently. Where molecular autopsy is combined with clinical evaluation of surviving relatives, a clinically relevant diagnosis is established in a substantially higher proportion of families than by either approach alone [12].

Cascade evaluation identifies relatives who carry risk before it manifests — the only circumstance in this field where prevention operates on a clearly identified population rather than an unselected one, and correspondingly the setting where the yield of evaluation is highest.

11. Knowledge Gaps

Several questions central to this field remain unresolved, and are unlikely to be settled by the study designs typically proposed.

Whether screening reduces mortality cannot be established by randomized trial. At an incidence near 1 per 63,682 athlete-years [4], demonstrating a 50% relative reduction with conventional power would require on the order of ten million athlete-years of observation. The Italian regional experience and the contradictory Israeli national experience are both observational [30,31], both confounded by secular trend and ascertainment change, and both are why the question remains open after four decades. This is a structural feature of studying a rare outcome, not a deficiency of effort.

The real-world false-positive rate is unknown. Published rates derive from expert interpretation. The rate achieved by clinicians who would actually staff population screening has not been established at scale, and it is the parameter that determines whether ECG-inclusive screening is feasible outside academic centers.

The magnitude of benefit from detection is uncertain and has probably narrowed. Legacy economic models assume that detection leads to restriction and that restriction prevents death. The second link has weakened considerably. Benefit now plausibly derives more from disease-specific treatment, family cascade screening, and targeted emergency preparedness than from removal from sport.

The true cost and completion rate of the diagnostic cascade are not established, because existing data derive from settings in which financially constrained individuals exit the pathway before completion.

The mechanism of the observed decline in incidence is unknown, and attributing it to screening is not supported by the data.

Sudden death in non-athletic young people is comparatively uncharacterized. The population is larger, the ascertainment poorer, and the preventive infrastructure absent.

12. Summary

Sudden cardiac death in the young is rare, concentrated, and heterogeneous in cause. Risk varies several-fold by sex, race, and sport, with Division I male basketball players the highest-risk studied group at roughly 1 in 2,000 over a four-year career. The etiologic picture is no longer dominated by hypertrophic cardiomyopathy: autopsy-negative sudden unexplained death is the most common single finding, and a meaningful fraction of these cases prove on molecular autopsy to be inherited arrhythmia syndromes.

Exercise acts as a trigger through catecholaminergic surge, demand ischemia, mechanical stress, electrolyte shift, and abrupt autonomic transition — and in at least one condition, plakophilin-2-mediated arrhythmogenic cardiomyopathy, as a driver of disease progression rather than merely a trigger.

Distinguishing physiological cardiac adaptation from disease is the central diagnostic challenge, and criteria for doing so on the ECG have improved markedly, reducing false-positive rates from roughly 40% to under 7% in Black athletes across fifteen years of refinement. Contemporary guidance on both sides of the Atlantic now regards ECG-inclusive screening as reasonable, conditioned on trained interpretation, assured access to secondary evaluation, and emergency preparedness.

Management has moved from categorical disqualification to shared decision-making, supported by outcome data showing lower risk from continued participation than was historically assumed. Detection produces benefit principally through disease-specific treatment, family cascade screening, and targeted preparedness rather than through removal from sport.

No screening strategy prevents all events. Emergency action planning, rapid recognition, immediate compressions, and early defibrillation remain the last and most reliable line of prevention, and in well-prepared settings save a majority of those who arrest.

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