Comparison of procainamide and lidocaine in terminating sustained monomorphic ventricular tachycardia

Efficacy of procainamide and lidocaine in terminating spontaneous monomorphic ventricular tachycardia (VT) was assessed in a randomized parallel study. Patients with acute myocardial infarction and those with poor hemodynamic tolerance of VT were excluded. Procainamide 10 mg/kg was given intravenously with an injection speed of 100 mg/min, and lidocaine was administered at an intravenous dose of 1.5 mg/kg in 2 minutes. Fourteen patients were randomized to lidocaine and 15 to procainamide. Termination occurred in 3 of 14 patients after lidocaine and in 12 of 15 patients after procainamide (p <0.01). Procainamide stopped 8 of 11 VTs not responding to lidocaine, and lidocaine stopped 1 of 1 not responding to procainamde. Of a total of 41 VT episodes, 4 of 15 responded to lidocaine and 20 of 26 to procainamide (p <0.01). Because of VT recurrences, 16 patients could be studied repeatedly with drugs given in the reversed order. This resulted in a total of 55 trials of 79 drug injections. Lidocaine terminated 6 of 31 VTs and procainamide 38 of 48 (p <0.001). The protocol was stopped in 4 cases because of adverse effects. A comparison of the QRS width and QT interval before and at the end of the injection revealed significant lengthening of these values after procainamide but no change after lidocaine. In conclusion, procainamide is superior to lidocaine in terminating spontaneously occurring monomorphic VT.