The authors studied 32 patients with ventricular arrhythmias--ventricular tachycardia (VT) or frequent ventricular extrasystoles (VES) and/or runs of extrasystole and cardiomyopathy with dilatation. This diagnosis was retained on the following criteria: absence of angina or electrical changes in infarction, normal coronary angiography in patients over the age of 50, diffuse abnormalities of ventricular contraction on 2D echocardiography or angiography, and on the absence of organic valvular heart disease. Thirteen patients had sustained paroxysmal VT, 18 patients had runs of VT and only 8 patients had isolated VES without repetition. The arrhythmia was polymorphic in 25 patients. All possible combinations of morphology of right of left sided delay with variable axes were observed. There were 25 right sided delays and 18 left sided delays; the association of left sided delay and vertical axis was only present in 5 occasions. Twelve patients underwent electrophysiological investigations for sustained VT but the arrhythmia could only be induced by ventricular extrastimulation in 4 cases. Eight patients were investigated during VT; the arrhythmia could only be terminated easily in 2 cases. Three of these 12 patients had biventricular tachycardia. Of the 11 patients with chronic alcoholism, only 2 had sustained VT, 8 had polymorphic VES and 1 monomorphic VES. Conversely, of the 21 patients without alcoholism, 11 had sustained VT, 6 had polymorphic VES, and 4 had monomorphic VES. There was a correlation between the polymorphism of the arrhythmia and the degree of ventricular dysfunction: of the 16 patients in overt cardiac failure (EF less than 30%), only 1 had monomorphic VT; the 15 others all had polymorphic arrhythmias. Only 2 had sustained VT.(ABSTRACT TRUNCATED AT 250 WORDS)