OBJECTIVE Characteristics of the site of origin of ventricular premature contraction in middle-aged patients with hypertension and silent myocardial ischemia were analyzed.METHODS Stratified sampling was used to select patients with ventricular premature contraction according to their 24h 12-lead dynamic electrocardiograms.The selected cases included 76 middle-aged patients with hypertension and silent myocardial ischemia(group Ⅰ),80 middle-aged hypertension patients without silent myocardial ischemia(group...