Sudden Cardiac Arrest After Endurance Cycling Due to Silent Three-Vessel Coronary Artery Disease: A Case Report

Sudden cardiac arrest (SCA) during endurance exercise in middle-aged athletes is uncommon but is most frequently caused by occult coronary artery disease (CAD). A 51-year-old, previously healthy, recreational cyclist collapsed immediately after completing a high-intensity 40-mile cycling event. He was found to be in ventricular fibrillation (VF) and achieved return of spontaneous circulation (ROSC) following prompt bystander cardiopulmonary resuscitation (CPR) and defibrillation. Initial electrocardiography and transthoracic echocardiography demonstrated no abnormalities and preserved left ventricular systolic function. Coronary angiography revealed severe three-vessel CAD, including critical proximal left anterior descending artery stenosis and chronic total occlusion of an obtuse marginal branch. The patient underwent successful coronary artery bypass grafting (CABG). Given the preserved ventricular function and a reversible ischemic cause, implantable cardioverter-defibrillator (ICD) implantation was not indicated. This case highlights the ability of high-intensity endurance exercise to unmask advanced, asymptomatic CAD and precipitate malignant ventricular arrhythmias in middle-aged athletes, emphasizing the importance of individualized cardiovascular risk assessment and emergency preparedness at endurance events.