Eighteen patients with sustained
ventricular tachycardia underwent serial electrophysiological studies to establish the therapeutic efficacy of
sotalol as compared to other available
anti-arrhythmic agents. One or more acutely effective
drug was found in 14 of the 18 patients (78%).
Sotalol was tested in all 18 patients and was effective in 12 of them (67%). For assessment of the prophylactic efficacy of other
anti-arrhythmic agents, an average of 3.5 additional studies per patient were performed resulting in successful prevention of
ventricular tachycardia in a total of 10 of 63 (16%) additional trials. Nine patients were placed on chronic oral
therapy with
sotalol. In these nine patients long-term prophylaxis against
ventricular tachycardia was documented over a mean follow-up period of 9.6 months (range 2-18 months). The study suggests that
sotalol can provide effective prophylaxis against
ventricular tachycardia in a significant proportion of patients refractory to other available drugs and that this prophylactic efficacy is predominantly due to its Class III
anti-arrhythmic properties. Experimental studies were performed in eight conscious dogs 3-7 days following proximal LAD
ligation. Epicardial recordings were obtained using implanted composite
electrodes.
Sotalol prevented sustained VT by a predominant increase in refractoriness of the infarcted zone. In vitro,
sotalol caused a significant prolongation of the action potential of epicardial and endocardial fibres within both the infarcted and noninfarcted myocardium. Refractoriness of epicardial ventricular fibres was significantly more prolonged in ischemically damaged cells as compared to normal fibres.