Acute effects of combination of IB and IC antiarrhythmics for the treatment of ventricular tachycardia.

There are limited data on the effects of Class IB and IC antiarrhythmic drug combination for the treatment of ventricular tachycardia. The present study evaluated this combination in 12 patients who had sustained ventricular tachycardia (SuVT) during programmed electrical stimulation (PES) and failed IC antiarrhythmic therapy. Following combination of lidocaine and a IC agent (7 with encainide and 5 with flecainide), two had no inducible ventricular tachycardia (VT) and one had nonsustained VT (NSVT). In seven of nine patients who still had SuVT, the mean VT cycle length increased 40 +/- 25 msec post combination compared to IC antiarrhythmic therapy. Seven patients who had a favorable response to the initial combination (less than 10 beats of NSVT, or greater than or equal to 10 beats of VT with a greater than 100 msec increase in cycle length compared to baseline and no hemodynamic compromise) were then placed on IC + oral IB agent (5 with mexiletine, 2 with tocainide). Similar effects on VT inducibility and cycle length were observed following the oral combination. In conclusion, the addition of lidocaine to IC therapy produced favorable effects on induced ventricular tachycardia in 58% of patients compared to IC agent alone. Also, a positive PES response to lidocaine and IC therapy corresponded to a similar positive response when either mexiletine or tocainide was substituted for lidocaine.