Cardiac magnetic resonance evaluation of structural heart disease in a large athlete cohort

Introduction Sudden cardiac death (SCD) in young athletes is most commonly related to underlying structural myocardial disorders. Cardiac magnetic resonance imaging (CMR) has emerged as a key diagnostic modality for detailed myocardial tissue characterization and for identifying substrates associated with malignant ventricular arrhythmias. Objective To assess the prevalence and spectrum of structural myocardial diseases detected by CMR in athletes and to evaluate the underlying etiologies associated with SCD and life-threatening ventricular arrhythmias. Methods Athletes performing ≥6 hours of weekly training who were referred to our center for CMR due to suspected structural heart disease were included. Genetic testing was performed in athletes with confirmed myocardial disease or documented malignant ventricular arrhythmias. Results A total of 857 athletes (752 males; mean age 25.3±11.3 years) underwent CMR evaluation. Referral indications included abnormal ECG findings (52%), cardiac symptoms (25%), echocardiographic abnormalities (19%), positive family history (10%), and resuscitation or sustained ventricular tachycardia (4%). Structural myocardial abnormalities were identified in 142 athletes (115 males; mean age 30.2±12.6 years; weekly training volume 12.3±6.5 hours). Among cardiomyopathies, hypertrophic cardiomyopathy (HCM) was diagnosed in 42 athletes, arrhythmogenic cardiomyopathy (AC) in 16, and dilated cardiomyopathy (DCM) in 12 cases. Non-ischemic myocardial fibrosis or scarring was detected in 52 athletes, including patterns consistent with acute or previous myocarditis and atypical fibrosis. Among athletes evaluated following resuscitation or sustained ventricular tachycardia, structural abnormalities were identified in 17 individuals, including AC (8 cases), HCM (1 case), mitral annular disjunction (1 case), ischemic injury (2 cases), and atypical fibrosis (5 cases). Genetic testing was performed in 53 athletes, revealing pathogenic or likely pathogenic variants in 14 cases and variants of uncertain significance in 25 cases. Follow-up information was obtained through telephone contact and review of available medical documentation in athletes with structural myocardial disease. Conclusions In this large athlete cohort, HCM was the most frequent cardiomyopathy, while AC was the predominant substrate associated with SCD. Beyond classical cardiomyopathies, atypical non-ischaemic myocardial scar represents a relevant structural finding in athletes undergoing CMR and may constitute an important arrhythmogenic substrate associated with malignant ventricular arrhythmias. CMR plays a pivotal role in identifying these subtle myocardial abnormalities, refining etiological classification, and improving risk stratification in athletes at potential risk for SCD.42-year-old runner evaluated after syncope