The Fragmented QRS Complex in Lead V 1 : Time for an Update of the Athlete's ECG?

Differentiating between ECG patterns related to athletes' heart remodeling and pathological findings is a challenge in sports cardiology. As the significance of fragmented complex in athletes remains uncertain, this study aimed to assess the presence of fragmented QRS in lead V 1 (fQRSV 1 ) among young athletes and its association with heart adaptations and arrhythmias. Young athletes referred for annual pre-participation screening receiving a maximal exercise testing and transthoracic echocardiography from January 2015 to March 2021 were included. The study included 684 young athletes. The prevalence of fQRSV 1 was 33%. Subjects with fQRSV 1 had higher exercise capacity and indexes of right ventricular function and remodeling. Among highly trained athletes, the fQRSV 1 group demonstrated also increased left ventricular wall thickness. No significant association existed between fQRSV 1 and exercise-induced arrhythmias, even in highly trained athletes. The high prevalence of fQRSV 1 in young athletes is associated with training-induced heart adaptations but not exercise-induced ventricular arrhythmias. The fragmented QRS complex in lead V 1 in young athletes. PPS = preparticipation screening; EST = exercise stress test; fQRSV 1  = fragmented QRS in lead V 1 ; PSBs = premature supraventricular beats; PVBs = premature ventricular beats.