Prognostic significance of frequent premature ventricular contractions originating from the ventricular outflow tract in patients with normal left ventricular function

Background: Recently, it has been reported that frequent premature ventricular contractions (PVCs) may be associated with causing heart failure in patients with left ventricular (LV) dysfunction. However, the prognostic significance of frequent PVCs in asymptomatic patients with a normal LV function is unclear. Methods: Two hundred and thirty-nine consecutive patients presenting with frequent PVCs (>1000 beats/day) originating from the right or left ventricular outflow tract without any detectable heart disease were enrolled in the study. Structural heart disease was ruled out by echocardiography and cardiac magnetic resonance imaging, and Holter-ECG monitoring was repeated two or three times to evaluate the PVC prevalence at the initial evaluation. All patients were followed up for at least 4 years, and further observation was continued if possible. Results: During an observation period of 5.6 (1.7) years, no patients exhibited any serious cardiac events. Although there was no significant change in the mean LV ejection fraction (LVEF) and mean LV diastolic dimension (LVDd), there was a significant negative correlation between the PVC prevalence and Delta LVEF (p<0.001) and positive correlation between the PVC prevalence and Delta LVDd (p<0.001). When the development of LV dysfunction was defined as Delta LVEF>-6%, 13 patients exhibited LV dysfunction. For the prediction of the development of LV dysfunction, PVC prevalence and LVEF at the initial evaluation were independent predicting factors (p<0.01). Conclusion: Although the prognosis in patients with frequent PVCs was considered relatively benign, attention should be paid to the progression of the LV dysfunction during a long-term observation, especially in patients with a high PVC prevalence.