[Emergency therapy of ventricular tachycardias: lidocaine versus ajmaline].

The efficacy of ajmaline (50-75 mg i.v.) or lidocaine (100-200 mg i.v.) in terminating persistent, haemodynamically stable ventricular tachycardia (VT) was compared in a prospective, randomized trial of 31 patients. There were no significant differences as to age, underlying heart disease, ejection fraction and rate of ventricular tachycardia between the two treatment groups. Ajmaline terminated VT in 10 of the 15 patients receiving it, lidocaine in only 2 of 16 (P less than 0.01). The frequency of VT was not significantly changed by lidocaine, while mean cycle length during VT changed under ajmaline from 369 +/- 82 ms to 452 +/- 11 ms (P less than 0.01). In contrast to lidocaine, QRS duration under ajmaline lengthened from 166 +/- 18 ms to 200 ms +/- 28 ms (P less than 0.01), but return cycles after tachycardia termination were similar (ajmaline, 863 +/- 296 ms; lidocaine, 917 +/- 367 ms). Both drugs were equally well tolerated, but in this series ajmaline was more effective in the acute treatment of persistent VT.