Ventricular arrhythmias in athletes: morphologic features and risk stratification of pathological myocardial substrate

Background Premature ventricular beats (PVBs) detected in apparently healthy athletes may raise concern for concealed cardiac disease associated with risk of malignant ventricular arrhythmias. Identifying electrocardiographic features that predict an underlying pathological substrate could improve risk stratification and guide second-line investigations. Purpose To determine which characteristics of PVBs recorded during exercise testing and 24-hour ECG monitoring predict the presence of structural or electrical cardiac disease in competitive athletes. Methods We enrolled 264 competitive athletes (79% male; median age 39 [20–53] years) referred for second-level evaluation of PVBs detected during pre-participation screening. Athletes with known cardiac disease were excluded. Clinical history, symptoms, family history of sudden cardiac death or cardiomyopathy, and resting ECG findings were collected. Ventricular arrhythmias were analysed for burden, morphology, complexity, reproducibility, and exercise inducibility. Cardiac magnetic resonance (CMR) was performed in 198 athletes. Associations with cardiac disease were assessed using multivariable analysis. Results Cardiac disease was diagnosed in 86 athletes (32%), most commonly nonischaemic left ventricular scar, arrhythmogenic cardiomyopathy, arrhythmic mitral valve prolapse, and channelopathies. Family history of sudden cardiac death or cardiomyopathy (p=0.002), symptoms suggestive of malignant arrhythmias (p=0.08), and resting ECG abnormalities (p=0.007) were more frequent in affected athletes. Polymorphic PVBs (69% vs 37.5%, p<0.001) and reproducible PVBs (94% vs 80%, p=0.009) were significantly associated with disease. Ventricular arrhythmias with right bundle branch block and superior/intermediate axis morphology were more prevalent in athletes with cardiac disease (75.5% vs 45%, p<0.001), particularly when accompanied by a wide monophasic R wave in V1 or intrinsecoid deflection >80 ms (47.7% vs 13.4%, p<0.001). Multivariable analysis identified symptoms, polymorphic PVBs, reproducibility, RBBB superior/intermediate-axis morphology with and wide R in V1 as independent predictors. Conclusions Underlying cardiac disease is present in a substantial proportion of athletes with PVBs detected during screening. Careful clinical assessment combined with detailed characterization of arrhythmic morphology improves identification of concealed pathological substrates. Specific PVB features—especially polymorphism, reproducibility, and RBBB superior/intermediate-axis morphology with wide R in V1—may represent practical markers for targeted diagnostic evaluation and refined risk stratification.