Ventricular and supraventricular arrhythmias in clinically silent right ventricular infarction.

To study the relationship between clinically silent right ventricular infarction and the incidence of a-v block, atrial and ventricular arrhythmias, 100 patients with inferior wall myocardial infarction underwent equilibrium gated radioisotopic angiocardiography. Fifty-four of them had radioisotopic evidence of right ventricular involvement and 43 (80%) of them had a-v block and/or supraventricular arrhythmias during the acute phase of the infarct, while only 10 (22%) of the 46 patients without right ventricular involvement did. As regards the incidence of ventricular tachyarrhythmias, 14 (26%) patients with right ventricular involvement had ventricular tachycardia and/or fibrillation, while only one patient without right ventricular involvement had ventricular tachycardia, and no patients had ventricular fibrillation. Moreover, V4R-precordial lead showed a sensitivity in predicting the risk of developing a-v block/supraventricular arrhythmias and ventricular tachyarrhythmias of 0.84 and 0.79, respectively. Therefore, right ventricular involvement should be suspected when atrial arrhythmias, a-v block and ventricular tachyarrhythmias are found in early acute inferior wall myocardial infarction. On the other hand, when right precordial lead V4R in early acute inferior infarction shows ST-elevation and/or a QS pattern, the sudden occurrence of these arrhythmias should be suspected, and possibly prevented.