Effect of circadian variability in frequency of premature ventricular complexes on left ventricular function

BACKGROUND Frequent idiopathic premature ventricular complexes (PVCs) can result in a reversible form of cardiomyopathy. OBJECTIVE The purpose of this study was to assess the impact of variability in PVC frequency throughout the day on PVC-induced cardiomyopathy. METHODS The subjects of this study were 107 consecutive patients (58 men [54%]; mean age 49.7 +/- 15.0 years; left ventricular ejection fraction 50.4% +/- 11.4%) referred for ablation of frequent PVCs. All patients underwent 24-hour Holter monitoring before the ablation procedure. The circadian variation in PVC burden was determined and correlated with the presence or absence of cardiomyopathy. RESULTS A total of 43 patients (40%) had cardiomyopathy. Patients with cardiomyopathy had an ejection fraction of 38.4% +/- 6.9%, a higher PVC burden (28.5% +/- 11.5% vs 19.5% +/- 10.5%; P=.0001), less variability in circadian PVC distribution (coefficient of variation hourly: 31.5% +/- 21% vs 59.8% +/- 32.4%; P=.0001), and more frequent interpolated PVCs (20 patients [47%] vs 15 patients [23%]; P = 0.022), and were more frequently asymptomatic than patients without cardiomyopathy (56% vs 19%; P=.0001). In multivariate analysis, consistency in PVC burden throughout the day was an independent predictor of PVC-induced cardiomyopathy (odds ratio 16.3; 95% confidence interval 1.7-155.3; p = 0.015). CONCLUSION In patients with frequent PVCs, consistency in hourly PVC frequency throughout the day is an independent predictor of PVC-induced cardiomyopathy.