Electrocardiographic Phenotypes Associated With Favorable Long-Term Outcome

Background—Early repolarization (ER) in inferior/lateral leads of standard ECGs increases the risk of arrhythmic death. We tested the hypothesis that variations in the ST-segment characteristics after the ER waveforms may have prognostic importance. Methods and Results—ST segments after ER were classified as horizontal/descending or rapidly ascending/upsloping on the basis of observations from 2 independent samples of young healthy athletes from Finland (n 62) and the United States (n 503), where ascending type was the dominant and common form of ER. Early repolarization was present in 27/62 (44%) of the Finnish athletes and 151/503 (30%) of the US athletes, and all but 1 of the Finnish (96%) and 91/107 (85%) of US athletes had an ascending/upsloping ST variant after ER. Subsequently, ECGs from a general population of 10 864 middle-aged subjects were analyzed to assess the prognostic modulation of ER-associated risk by ST-segment variations. Subjects with ER 0.1 mV and horizontal/descending ST variant (n 412) had an increased hazard ratio of arrhythmic death (relative risk 1.43; 95% confidence interval 1.05 to 1.94). When modeled for higher amplitude ER ( 0.2 mV) in inferior leads and horizontal/descending ST-segment variant, the hazard ratio of arrhythmic death increased to 3.14 (95% confidence interval 1.56 to 6.30). However, in subjects with ascending ST variant, the relative risk for arrhythmic death was not increased (0.89; 95% confidence interval 0.52 to 1.55). Conclusions—ST-segment morphology variants associated with ER separates subjects with and without an increased risk of arrhythmic death in middle-aged subjects. Rapidly ascending ST segments after the J-point, the dominant ST pattern in healthy athletes, seems to be a benign variant of ER. (Circulation. 2011;123:2666-2673.)