Since its initial description nearly 80 years ago, the early repolarization pattern (ERP) has been considered a normal electrocardiographic variant. It is characterized by J point elevation manifested either as terminal QRS slurring (the transition from the QRS segment to the ST segment) or notching (a positive deflection inscribed on terminal QRS complex) associated with concave upward ST-segment elevation and prominent T waves in at least two contiguous leads.¹

Take-aways Early repolarization (ERP) is a common finding in young, healthy, competitive athletes and appears to be a direct result of exercise training. Both ERP and an inferior subtype (originally thought to increase risk of sudden death) increase in prevalence after intense physical training. However, in an analysis of nearly 900 collegiate athletes, there were no associations between ERP and echocardiographic measures of left ventricle remodeling, including chamber volume or wall thickness, well-established components of the "athlete heart." Thus, while exercise training may be causal in the development of ERP, it seems to be more of an isolated electric phenomenon that develops in parallel but not as a result of structural myocardial remodeling and should not trigger additional costly testing when first detected.

Despite its characterization as a benign variant, preliminary evidence has suggested that ERP in the inferior leads is associated with an increased risk of sudden cardiac death (SCD) in middle-aged adults. It was a shock when this was first reported in 2008 by Haissaguerre et al. in the New England Journal of Medicine.²

Until 2011, the prevalence, clinical associations, and underlying mechanisms of this potentially malignant ERP subtype remained largely unstudied in young competitive athletes. Then Aaron L. Baggish, MD, and others reported the results of their assessment of ERP in a cross-sectional cohort of athletes (n = 879) enrolled in the Harvard Athletics Initiative, an ongoing effort designed to address numerous aspects of student-athlete cardiovascular health.³

Included in the study was an examination of the relationship between ERP and cardiac structure in a longitudinal subgroup of 146 athletes before and after a 90-day period of exercise training.

They found that nonanterior ERP was present in 25.1% of the entire cohort, including the inferior subtype in 3.8% (33 of 879 athletes). The authors said theirs is the first study to demonstrate that exercise training is causal in the development of ERP. Specifically, both ERP and the inferior subtype increased in prevalence after intense physical training.

Interestingly, neither ERP nor the inferior subtype was associated with the structural left ventricular measures, including chamber volume or wall thickness, both of which are well-established components of the "athlete heart."

The authors wrote, "These data suggest that exercise-related ERP may be an isolated electric phenomenon that develops in parallel but not as a result of structural myocardial remodeling. In aggregate, our data suggest that ERP [including the inferior subtype] is a common finding in young, healthy, competitive athletes that is a direct result of exercise training."

Important Clinical Implications
Baggish et al. said their study has significant implications with respect to the care of the athletic patient. Nonanterior ERP, including the inferior subtype, is a common characteristic of the electrocardiogram (ECG) of many healthy athletes and does not indicate an underlying structural abnormality. When detected by ECG during pre-participation screening, preoperative clearance, or a routine health maintenance physical examinations in an asymptomatic athlete, ERP should not necessarily mandate further costly diagnostic testing.

Dr. Baggish said that the increased mortality associated with ERP does not appear until about the fourth or fifth decade of life—about the time individuals start to develop atherosclerosis. So, even though athletes were studied with ECGs in their teens and early twenties, there was no separation of survival curves until they started to age. Thus, the relevance of ERP in healthy, young athletes is unclear. He emphasized that there has not been a single observation of a death associated with isolated early repolarization in an athlete anywhere, so it does not appear to be a mortality signal in young, healthy people.

The authors added that practitioners should recognize that ERP is a dynamic process that is more likely to be observed in healthy athletes at times of peak fitness. Further investigation is warranted, they wrote, to fully characterize the prognostic implications of ERP in competitive athletes.

References

1. Derval N, Shah A, Jaïs P. Circulation. 2011;124:2185-6.
2. Haissaguerre M, Derval N, Sacher F, et al. N Engl J Med. 2008;358:2016-23.
3. Noseworthy PA, Weiner R, Kim J, et al. Circ Arrhythm Electrophysiol. 2011;4:432-40.

To listen to an interview with Aaron L. Baggish, MD, about early repolarization in athletes, visit youtube.cswnews.org. The interview was conducted by W. Douglas Weaver, MD.

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