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Premature contractions of the ventricle, the most common of all arrhythmias. In the absence of heart disease, they are not of great clinical significance, but in patients with coronary disease, they represent a constant danger of ventricular tachycardia or fibrillation and sudden death. The longer-term prognosis for asymptomatic, healthy subjects with frequent and complex ectopy is similar to that for the healthy United States population. (From Sokolow, et al., Clinical Cardiology, 5th ed, p491)