[Clinical-electrophysiological study of the effect of lorcainide on induction of ventricular tachycardia (author's transl)].

11 patients (mean age 52 +/- 16.3 years) with recurrent ventricular tachycardia (VT), in whom VT could be initiated by programmed ventricular stimulation, were studied before and after lorcainide, a new antiarrhythmic agent. Lorcainide was either injected intravenously at a dose of 2 mg/kg within five to ten minutes (n = 3) or infused at a rate of 0.1 mg/kg/min up to the same total dose. After intravenous administration, there was no change in inducibility of VT in three patients, whereas in seven patients VT was either more difficult to induce requiring two instead of one premature beat (n = 2) or a higher rate of basic pacing (n = 2) or VT was no longer inducible (n = 3). In one case, VT was easier to induce. In patients with still inducible VT, the rate of VT decreased from 220 +/- 33 b.p.m. to 186 +/- 49.1 b.p.m. (non-significant). The echo zone for initiation of VT did not show any consistent change. The coupling interval between the last stimulated complex and the first beat of VT increased from 327 +/- 66.8 ms to 390 +/- 98.6 ms (p less than 0.05). The effective refractory period of the right ventricle increased slightly though not significantly. In three cases paradoxical side effects, probably due to lorcainide, were observed. The blood level of lorcainide at the end of injection or infusion immediately before right ventricular stimulation was 0.69 +/- 0.48 micrograms/ml (range 0.11 to 1.74 micrograms/ml). No N-dealkylated metabolite of lorcainide was detected after intravenous injection. Thus far, lorcainide is effective in preventing initiation of VT in some patients making it more difficult to induce in others. However, long-term efficacy and tolerance to the drug cannot be predicted from the data of this study though the data suggest that the drug might be effective on the long-term run against ventricular tachyarrhythmias.