Prediction of mortality and serious ventricular arrhythmia in hypertrophic cardiomyopathy. An echocardiographic study.

M-mode echocardiography was performed on 26 patients with clinical and angiographic hypertrophic cardiomyopathy to assess the echocardiographic prediction of serious ventricular arrhythmia. These patients had previously undergone 48-hour ambulatory electrocardiographic monitoring both on and off beta-adrenergic blocking drugs and were grouped according to the most serious ventricular arrhythmia detected: (A) ventricular tachycardia, eight patients; (B) multiform or paired ventricular extrasystoles, 11 patients; (C) uniform ventricular extrasystoles, seven patients. Septal amplitude of motion at chordal level and septal systolic thickening showed a significant difference between group A and C, and group B and C. Systolic anterior movement of the mitral valve and mid-systolic closure of the aortic valve were detected with identical frequency and were both seen in two patients (25%) in group A, seven patients (64%) in group B, and six patients (86%) in group C. These echocardiographic features of obstruction were inversely correlated with ventricular tachycardia. Septal amplitude of motion was then assessed just below the mitral valve and at chordal level by continuous sweep recording and the pattern of septal motion was graded from normal (type I) to absent (type V) or as paradoxical (type VI). Six patients (75%) in group A showed type IV, V, or VI; seven patients (64%) in group B showed type III; and six patients (86%) in group C showed type I or II. The patients with ventricular tachycardia were the patients with the most severely impaired pattern of septal motion.