Long runs of non-sustained ventricular tachycardia on 24-hour ambulatory electrocardiogram predict major arrhythmic events in patients with idiopathic dilated cardiomyopathy.

This study examined the prognostic significance of the rate and length of non-sustained (NS) ventricular tachycardia (VT) on 24-hour ambulatory electrocardiograms (ECG) recorded in 343 patients with idiopathic dilated cardiomyopathy (IDC) in the prospective Marburg Cardiomyopathy study. NSVT was defined as >/=3 consecutive ventricular premature beats at >120 bpm. During 52 +/- 21 months of follow-up, major arrhythmic events defined as sustained VT, VF, or sudden cardiac death occurred in 46 of 343 patients (13%). Patients with 3-4 beat runs of NSVT had a similar arrhythmia-free survival as patients without NSVT on baseline 24-hour ambulatory ECG. The incidence of major arrhythmic events during follow-up increased significantly from 2% per year in patients without NSVT, to 5% per year in patients with 5-9 beat runs of NSVT, to 10% per year in patients with >/=10 beat runs of NSVT (P < 0.05). Unlike the length, the rate of NSVT was similar in patients with versus without subsequent major arrhythmic events (163 +/- 23 vs 160 +/- 24 bpm). Thus, the length but not the rate of NSVT on 24-hour ambulatory ECG was a predictor of major arrhythmic events in patients with IDC. The presence of NSVT with >/=10 beat runs on ambulatory ECG was associated with a particularly high risk of major arrhythmic events.