The prognostic importance of exercise-induced ventricular arrhythmia (EIVA) remains unclear. Left bundle branch block (LBBB)-morphology ventricular ectopics may originate from the right ventricular outflow tract and are often benign, whereas right bundle branch block (RBBB)-morphology ventricular ectopics may originate from the left ventricular and may be associated with left ventricular (LV) disease or depressed LV function.

In a retrospective cohort study, Eckart and colleagues investigated the relationship between the presence (n = 585) or absence (n = 2340) of EIVA during exercise stress testing and future rates of adverse cardiovascular events. Patients were matched by age, sex and risk factor profile.

During an average follow up period of 24 months, mortality rates were higher among patients with EIVA as compared to those without (5.3% vs 1.8%, p<0.001). Survival was worst among the group with RBBB-morphology or multiple-morphology EIVA (6.9%), whereas patients with LBBB-morphology EIVA had a mortality rate similar to those without EIVA (2.5%).  Furthermore, among patients without known coronary artery disease any RBBB-morphology EIVA was associated with death (HR 2.73 [95% CI, 1.78 to 4.13]; p<0.001) but LBBB-morphology EIVA was not (HR 0.82 [95% CI, 0.18 to 2.04]; p=0.72).

Although not all LBBB-morphology EIVA can be dismissed as low risk, the authors suggest that at the very least the presence of RBBB-morphology EIVA may be a useful indicator of high cardiovascular risk, and should prompt further investigation.

• Eckart RE, Field ME, Hruczkowski TW et al.  Association of Electrocardiographic Morphology of Exercise-Induced Ventricular Arrhythmia with Mortality.  Ann Intern Med 2008;149:451-460