The Fragmented QRS Complex in Lead V1: Time for an Update of the Athlete’s ECG?

Abstract

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 V1 (fQRSV1) 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 fQRSV1 was 33%. Subjects with fQRSV1 had higher exercise capacity and indexes of right ventricular function and remodeling. Among highly trained athletes, the fQRSV1 group demonstrated also increased left ventricular wall thickness. No significant association existed between fQRSV1 and exercise-induced arrhythmias, even in highly trained athletes. The high prevalence of fQRSV1 in young athletes is associated with training-induced heart adaptations but not exercise-induced ventricular arrhythmias. Graphical Abstract The fragmented QRS complex in lead V1 in young athletes. PPS = preparticipation screening; EST = exercise stress test; fQRSV1 = fragmented QRS in lead V1; PSBs = premature supraventricular beats; PVBs = premature ventricular beats.

Physiological Changes in QRS Fragmentation in Athletes and Nonathletes without Cardiac Disease

“…These findings may reflect the fact that a dilated RV outflow tract could be associated with a greater angulation of the RV myocardial band at the transition site from the RV free wall to pulmonary conus, leading to a more sudden change in the direction of RV electrical activation in the RV outflow tract [30]. Although two previous studies have reported increased prevalence of QRS fragmentation in V1 among athletes and its association with indexes of RV dimensions, the QRS fragmentation was defined in a restrictive way as the presence of quadriphasic QRS complex without including cases with notched QRS in V1 [11,12]. Moreover, the disappearance of QRS fragmentation in V1 after deep inspiration in the healthy nonathletes of the current study could be explained by the inspiration-induced clockwise rotation of the heart minimizing the view of the RV outflow track by V1 [33].…”

“…Thirdly, the current study assessed QRS fragmentation in each specific lead and not only in groups of contiguous leads. Furthermore, we defined the QRS fragmentation in V1 broadly, including all the subcategories of QRS fragmentation, as opposed to the restrictive definition of previous studies investigating only the presence of quadriphasic QRS complex without including cases with notched QRS in V1 [11,12]. Finally, the present study investigated QRS fragmentation in individuals with a wide age range, including not only children and adolescents but also elderly individuals.…”

“…However, relatively few studies have explored the clinical significance of QRS fragmentation in athletes, since the overwhelming majority of the medical literature investigating QRS fragmentation has focused on populations with known cardiac disease [1,11,12]. A limitation of the studies having investigated QRS fragmentation in athletes so far was that they analyzed the prevalence of QRS fragmentation only in groups of contiguous electrocardiographic leads, essentially leaving unexplored the clinical significance of QRS fragmentation in each specific lead, with the only exception of V1, the QRS fragmentation of which was defined in a restrictive way as the presence of quadriphasic QRS complex without including cases with notched QRS in V1 [1,11,12].…”