title: Early repolarization: electrocardiographic phenotypes associated with favorable long-term outcome.
abstract: 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.
  
  
  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.
authors.affiliation: Institute of Clinical Medicine, Department of Internal Medicine, University of Oulu, Oulu, Finland. jani.tikkanen@oulu.fi
authors.forename: Jani T
authors.initials: JT
authors.lastname: Tikkanen
authors.forename: M Juhani
authors.initials: MJ
authors.lastname: Junttila
authors.forename: Olli
authors.initials: O
authors.lastname: Anttonen
authors.forename: Aapo L
authors.initials: AL
authors.lastname: Aro
authors.forename: Samuli
authors.initials: S
authors.lastname: Luttinen
authors.forename: Tuomas
authors.initials: T
authors.lastname: Kerola
authors.forename: Solomon J
authors.initials: SJ
authors.lastname: Sager
authors.forename: Harri A
authors.initials: HA
authors.lastname: Rissanen
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Myerburg
authors.forename: Antti
authors.initials: A
authors.lastname: Reunanen
authors.forename: Heikki V
authors.initials: HV
authors.lastname: Huikuri
mesh_terms: D000293:Adolescent; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000401:mortality*; D016757:Death, Sudden, Cardiac / Q000453:epidemiology* / Q000517:prevention & control*; D004562:Electrocardiography; D005387:Finland / Q000453:epidemiology; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D010865:Pilot Projects; D011379:Prognosis; D012307:Risk Factors; D013177:Sports / Q000706:statistics & numerical data; D013997:Time Factors; D014481:United States / Q000453:epidemiology