Procainamide was significantly more effective than lidocaine in suppressing electrically inducible ventricular tachycardia in post-myocardial infarction patients (44.7% vs 7.1%; p<0.01).
Does procainamide compared to lidocaine improve the suppression of electrically inducible ventricular tachycardia in post myocardial infarction patients?
Procainamide is more effective than lidocaine for suppressing electrically inducible ventricular tachycardia in post-MI patients, though both drugs carry a risk of worsening arrhythmias.
Absolute Event Rate: 44.7% vs 7.1%
p-value: p=<0.01
The effects of procainamide and lidocaine, representative of class IA and IB antiarrhythmic agents, on electrically inducible ventricular tachycardia (VT) were studied using programmed ventricular stimulation in 47 post myocardial infarction patients at an average of 1.5 months after the onset. The mean doses of administered procainamide and lidocaine were 1050 mg and 161 mg, and their mean plasma concentrations were 7.5 micrograms/ml and 3.1 micrograms/ml respectively. The induction of sustained VT was suppressed in 15 of 29 patients (52%) by procainamide, but in none by lidocaine. The induction of nonsustained VT was suppressed in 6 of 18 patients (33%) by procainamide, and in 1 of 8 patients (13%) by lidocaine. The efficacy rate of procainamide was significantly higher than that of lidocaine in suppression of VT induction (21/47 vs 1/14 p less than 0.01). Procainamide significantly prolonged the effective refractory period of the right ventricle as well as the HV and QRS interval, however lidocaine did not affect them significantly. On the other hand, the worsening effect which changed nonsustained VT inducible in the baseline into sustained VT inducible post drug administration was demonstrated in 8 of 18 procainamide cases (44%), and in 3 of 8 lidocaine cases (38%). Between the procainamide effective and ineffective or worsening patients, there were no differences found in the electrophysiologic variables either in the baseline or post procainamide administration. We concluded that procainamide was more effective than lidocaine for the prevention of potential life-threatening VT induction in post myocardial infarction patients, although its efficacy was considerably limited, and to confirm the effectiveness and exclude the worsening effects of the class IA and IB antiarrhythmic agents, drug testing using programmed ventricular stimulation appeared to be valuable.
Iesaka et al. (Fri,) conducted a other in Post myocardial infarction with electrically inducible ventricular tachycardia (n=47). Procainamide vs. Lidocaine (mean dose 161 mg) was evaluated on Suppression of ventricular tachycardia induction (p=<0.01). Procainamide was significantly more effective than lidocaine in suppressing electrically inducible ventricular tachycardia in post-myocardial infarction patients (44.7% vs 7.1%; p<0.01).