The effects of lidocaine, tocainide and mexiletine were examined in 17 patients with coronary artery disease and chronic, recurrent, sustained ventricular tachycardia (VT) or ventricular fibrillation and inducible VT. Eleven patients presented with sustained VT; 6 patients had had an episode of sudden death from which they had been resuscitated. All patients were refractory to conventional antiarrhythmic agents. Lidocaine prevented induction of VT in only 3 patients (18%). Tocainide prevented induction of VT in only 1 lidocaine-responsive patient. Mexiletine prevented VT induction in 1 patient who had responded to lidocaine but not tocainide. Neither tocainide nor mexiletine was effective in preventing induction of VT in any patient who did not respond to lidocaine. Lidocaine terminated VT in 3 patients, but this did not predict noninducibility with lidocaine, tocainide or mexiletine. Cycle length of VT was prolonged slightly by lidocaine (control 311 ± 14 ms, lidocaine 361 ± 26 ms, p < 0.05), tocainide (344 ± 16 ms, p < 0.05) and mexiletine (371 ± 27 ms, mean ± standard error of the mean, p < 0.05). Thus, class lb agents are infrequently effective in preventing induction of VT in this group of patients, electrophysiologic inefficacy of lidocaine is highly predictive of continued inducibility with tocainide and mexiletine, and termination of VT with lidocaine does not correlate with its ability to prevent VT induction.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine