title: Prevalence and prognostic value of exercise-induced ventricular arrhythmias.
abstract: OBJECTIVE
  The purpose of this study was to determine the prevalence and prognostic significance of exercise-induced ventricular arrhythmias (EIVAs) in patients referred for exercise testing, considering the arrhythmic substrate and exercise-induced ischemia.
  
  
  BACKGROUND
  EIVAs are frequently observed during exercise testing, but their prognostic significance is uncertain. The design of this study was a retrospective analysis of prospectively collected data, and it took place in 2 university-affiliated Veterans Affairs Medical Centers. Patients comprised 6213 consecutive males referred for exercise tests. We measured clinical exercise test responses and all-cause mortality after a mean follow-up of 6 +/- 4 years. EIVAs were defined as frequent premature ventricular contractions (PVCs) constituting >10% of all ventricular depolarizations during any 30 second electrocardiogram recording, or a run of > or =3 consecutive PVCs during exercise or recovery.
  
  
  RESULTS
  A total of 1256 patients (20%) died during follow-up. EIVAs occurred in 503 patients (8%); the prevalence of EIVAs increased in older patients and in those with cardiopulmonary disease, resting PVCs, and ischemia during exercise. EIVAs were associated with mortality irrespective of the presence of cardiopulmonary disease or exercise-induced ischemia. In those without cardiopulmonary disease, mortality differed more so later in follow up than earlier. In those without resting PVCs, EIVAs were also predictive of mortality, but in those with resting PVCs, poorer prognosis was not worsened by the presence of EIVAs.
  
  
  CONCLUSIONS
  Exercise induced ischemia does not affect the prognostic value of EIVAs, whereas the arrhythmic substrate does. EIVAs and resting PVCs are both independent predictors of mortality after consideration of other clinical and exercise-test variables. These findings are of limited clinical significance because of the modest change in risk and the lack of any established intervention. However, they explain some of the previous controversy and highlight the need to consider resting PVCs and follow-up duration in assessing the clinical implications of EIVAs.
authors.affiliation: McMaster University, Hamilton, Ontario, Canada.
authors.forename: Sara
authors.initials: S
authors.lastname: Partington
authors.forename: Jonathan
authors.initials: J
authors.lastname: Myers
authors.forename: Shaun
authors.initials: S
authors.lastname: Cho
authors.forename: Victor
authors.initials: V
authors.lastname: Froelicher
authors.forename: Sung
authors.initials: S
authors.lastname: Chun
mesh_terms: D004562:Electrocardiography; D005080:Exercise Test; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment; D015996:Survival Rate; D014693:Ventricular Fibrillation / Q000175:diagnosis* / Q000453:epidemiology*; D014728:Veterans