Asymptomatic ventricular arrhythmias and mortality risk in subjects with left ventricular hypertrophy.

OBJECTIVES: The purpose of this study was to evaluate the long-term prognostic role of asymptomatic ventricular arrhythmias in original Framingham Heart Study subjects and Framing-ham Offspring Study subjects who had echocardiographic evidence of left ventricular hypertrophy.
BACKGROUND: Echocardiographically determined left ventricular hypertrophy is associated with increased risk for ventricular arrhythmias. There are no population-based data available with regard to the long-term prognostic implications of asymptomatic ventricular arrhythmias in subjects with left ventricular hypertrophy.
METHODS: In a population-based cohort study, we studied 224 men and 393 women with echocardiographically determined left ventricular hypertrophy who were free of coronary heart disease and had 1-h ambulatory electrocardiograms at the baseline examination. The age-adjusted prevalence of complex or frequent ventricular arrhythmias (> 30 ventricular premature beats/h, multiform premature complexes, couplets, ventricular tachycardia or R on T ventricular premature complexes) was 28% (51 of 224) in men and 17% (71 of 393) in women. The mean follow-up period was 5.7 years for cohort and 4.5 years for offspring subjects.
RESULTS: In men with complex or frequent arrhythmias, the 6-year cumulative incidence of all-cause mortality was 38%, whereas in those free of arrhythmia it was 12%; corresponding values in women were 22% and 11%. The cumulative incidence of myocardial infarction or death due to coronary heart disease was 20% for men with and 10% for men without arrhythmia, but in women little difference was noted (5% vs. 4%). After adjustment for age and gender in a Cox proportional hazards model, subjects with complex or frequent arrhythmia were at increased risk for all-cause mortality (hazard ratio 1.80, 95% confidence interval [CI] 1.13 to 2.87, p = 0.013). After adjusting for eight clinical covariates, the increased risk for all-cause mortality remained marginally significant (hazard ratio 1.62, 95% CI 0.98 to 2.68, p = 0.058). No significant increased risk was noted for myocardial infarction or death due to coronary heart disease.
CONCLUSIONS: In subjects with left ventricular hypertrophy, the presence of asymptomatic ventricular arrhythmias was associated with higher mortality, which was statistically significant after adjusting for age and gender and marginally significant after taking into account other covariates.