Background Ventricular arrhythmias cause a significant proportion of sudden deaths. Several studies demonstrate a high prevalence of ventricular arrhythmias in patients with heart failure regardless of the etiology. The aim of this study was to determine the prevalence of silent ventricular arrhythmias in ambulatory heart failure patients with reduced left ventricular ejection fraction (HFrEF) and its correlation to the prognosis. Results Four hundred (400) ambulatory HFrEF patients on maximum tolerated doses of heart failure medications were included. Holter monitoring for 7 days was done in all patients searching for silent ventricular arrhythmias. The patients were followed-up for one year to detect the occurrence of major adverse cardiovascular events. We divided the study population into 2 groups based on an LVEF cutoff value of 30% (Group A Conclusions ventricular arrhythmias are common in HFrEF patients even in the compensated status. Both, left ventricular systolic function and the PVCs burden were found to be the strongest predictors of major adverse cardiovascular events.