Active Voice: Early Repolarization – Significance in Athletes
By: Philip Aagaard, M.D., Ph.D.
Viewpoints presented in SMB commentaries reflect opinions of the authors and do not necessarily reflect positions or policies of ACSM.
Philip Aagaard is a physician and researcher at Montefiore Medical Center - The University Hospital of Albert Einstein College of Medicine in the Bronx, New York. His research interests include prevention of sudden cardiac death in athletes and the athlete’s ECG.
This commentary presents Dr. Aagaard’s views related to a research report that he and his colleagues authored, which appears in the July 2014 issue of Medicine & Science in Sports & Exercise® (MSSE).
For decades, early repolarization (ER) was considered a benign ECG finding. However, this view was recently challenged by studies associating early repolarization with an increased risk of arrhythmic death in the general population.
Physical training can induce early repolarization, possibly by increasing vagal tone. It is therefore not surprising that early repolarization is prevalent in athletes. In fact, it is even considered a feature of an athlete’s heart. However, in one related study, it was reported that early repolarization was more common in athletes suffering sudden cardiac arrest compared with control athletes. This has sparked debate regarding the significance of early repolarization in the athletic population.
Our group set out to investigate the prevalence of early repolarization in middle-aged males planning a first-time participation in a long-distance running race (Lidingöloppet 30km). This constitutes a rapidly growing group considered at increased risk for exercise induced sudden cardiac death. In our recent research article published in MSSE, we reported on these data. We found that ER was a common finding, present in 44 percent of runners. However, despite a thorough cardiovascular evaluation including history and physical exam, ECG, vectorcardiography, echocardiography and laboratory tests, we did not discover any concerning associations between the presence of ER and other cardiovascular findings. On the contrary, regardless of localization or morphology, ER was associated with features of better physical fitness such as a lower body mass index (BMI), better lipid profile, and with other features of the athlete’s heart, including a lower resting heart rate (should probably spell this out). The association between physical fitness markers and early repolarization was further corroborated by faster race times in the early repolarization group.
An important and novel finding of this study was that the early repolarization pattern disappeared in most subjects after completion of the race. This suggests a significant role for increased vagal activity in the genesis of early repolarization, as vagal tone is decreased acutely after endurance exercise. Furthermore, the absence of early repolarization after race completion supports its benign nature as the pathognomonic ECG pattern would be expected to be present to support an association between early repolarization and exercise-related arrhythmias.
These findings are of clinical importance and imply that, on a group level, early repolarization should be regarded as a common and seemingly training-related finding in middle-aged physically active men. The role of ECG in pre-participation screening of athletes is an ongoing debate in the United States. Our results are relevant for the interpretation of ECGs in this setting: athletes with early repolarization on ECG should be reassured.