Clinical meaning
The preparticipation physical evaluation (PPE) aims to identify conditions predisposing athletes to sudden cardiac death (SCD), musculoskeletal injury, or heat illness. SCD in athletes <35 years is primarily caused by structural cardiac abnormalities: hypertrophic cardiomyopathy (HCM, 36%), coronary artery anomalies (17%), arrhythmogenic right ventricular cardiomyopathy (ARVC, 11%), myocarditis (6%), and ion channel disorders (long QT syndrome, Brugada syndrome, catecholaminergic polymorphic VT). HCM involves mutations in sarcomeric protein genes (beta-myosin heavy chain, myosin-binding protein C) causing asymmetric septal hypertrophy (>= 15 mm in adults), myocyte disarray, and interstitial fibrosis, creating substrate for ventricular tachycardia/fibrillation during exercise. Coronary artery anomalies (anomalous origin of left coronary from right sinus with interarterial course) cause SCD through external compression between the aorta and pulmonary artery during exercise-induced aortic root expansion. In athletes >35 years, atherosclerotic coronary artery disease is the predominant cause. Commotio cordis (sudden cardiac arrest from blunt chest impact during the vulnerable phase of repolarization - T-wave window) occurs in youth sports with projectile impact. Exercise-induced physiologic cardiac remodeling (athlete's heart) must be distinguished from pathologic hypertrophy: athlete's heart shows symmetric LVH (typically <13 mm wall thickness), LV cavity dilation, normal diastolic function, and regression with detraining.