Studies of patients undergoing catheter ablation have shown that premature ventricular contractions (PVCs) are a modifiable risk factor for congestive heart failure (CHF). the relationship between the frequency of PVCs, CHF events, and mortality in the general population remains unknown. The purpose of this population-based cohort study – using 24-hour ambulatory ECG monitoring – was to determine whether the frequency of PVCs predicted reduced left ventricular ejection fraction (LVEF), CHF events, and mortality. Researchers studied 1,139 participants in the Cardiovascular Health Study (CHS) who were randomly assigned to 24-hour ambulatory ECG (or electrocardiogram) monitoring and who had a normal LVEF and a history of congestive heart failure. Using ambulatory ECG to study PVC frequency quantification, LVEF was measured from baseline and echocardiography at 5 years. Participants were followed for CHF events and death. Multivariate adjustment of the upper quartile of PVC frequency with the lowest quartile increased the odds of a more than threefold decrease in LVEF over 5 years (ratio [OR]: 3.10; 95% confidence interval (Cl): 1.42 to 6.77; P=0.005) and a 48% increased risk of CHF events (HR: 1.48; 95% Cl: 1.08 to 2.04; P = 0.02), and a 31% increased risk of death (HR: 1.31; 95% Cl: 1.06 to 1.63; P = 0.01) with a median follow-up of >13 years. Significantly similar statistical results were seen when PVCs were included as a continuous variable. The 15-year risk of CHF exceeded 90% when PVCs included at least 0.7% of premature ventricular contractions. the population-level risk of CHF attributable to PVCs was 8.1% (95% Cl: 1.2% to 14.9%). In a population-based sample, higher frequency of PVCs was associated with reduced LVEF, increased CHF events, and increased mortality. Since PVCs can be prevented by medical or ablative therapy, PVCs may represent a manageable risk factor for CHF and mortality.