Early repolarization in middle-age runners: cardiovascular characteristics.

Purpose: This study aimed to assess the prevalence and patterns of early repolarization (ER) in middle-age long-distance runners, its relation to cardiac structure and function, and its response to strenuous physical activity.
Methods: Male first-time cross-country race participants >45 yr were assessed pre- and postrace by medical history and physical examination, 12-lead ECG, vectorcardiography, blood tests, and echocardiography. ER was defined either as ST elevation or J wave and categorized according to localization and morphology.
Results: One hundred and fifty-one subjects (50 ± 5 yr) were evaluated before the race, and 47 subjects were evaluated after the race. Altogether, 67 subjects (44%) had ER. Subjects with versus without ER had a lower resting HR (56 ± 8 vs 69 ± 9 bpm, P = 0.02), lower body mass index (24 ± 2 vs 25 ± 3 kg·m(-2), P < 0.001), higher training volume (3.0 ± 2.6 vs 2.1 ± 2.7 h·wk(-1), P = 0.03), and faster 30-km running times (194 ± 28 vs 208 ± 31 min, P = 0.01). Vectorcardiography parameters in subjects with ER showed more repolarization heterogeneity: vector gradient (QRS-T(area)) (120 ± 25 vs 92 ± 29 μVs, P < 0.001), T(area) (105 ± 18 vs 73 ± 23 μVs, P < 0.001), and T(amplitude) (0.63 ± 0.13 vs 0.53 ± 0.16 mm, P < 0.001); these parameters were inversely related to HR (r = -0.37 to -0.48, P < 0.001). ER disappeared in 15 (75%) of 20 subjects after the race.
Conclusions: ER is a common finding in middle-age male runners. This ECG pattern, regardless of morphology and localization, is associated with normal cardiac examinations including noninvasive electrophysiology, features of better physical conditioning, and disappears after strenuous exercise in most cases. These findings support that ER should be regarded as a common and training-related finding also in middle-age physically active men.