A multicenter observational study of the effectiveness of antiarrhythmic agents in ventricular arrhythmias: A propensity-score adjusted analysis

BACKGROUND Ventricular tachyarrhythmias (VTs) are life-threatening events that result in hemodynamic compromise. Recurrence is common and may worsen a patient׳s clinical course despite appropriate treatment. This study aimed to examine the effectiveness of antiarrhythmic drugs for suppression of VTs. METHODS In this cohort study, eligible patients were those who were admitted to one of the nine cardiovascular care centers and treated with continuous infusion of an antiarrhythmic drug for at least 1 h to prevent recurrence of VTs after return of spontaneous circulation. To adjust for differences in baseline characteristics among treatment groups, propensity scores for administered agents were generated and used as covariates in regression analyses. RESULTS Seventy-two patients were enrolled and 67 patients were included in the final analysis. Amiodarone (n=21, 31.3%), nifekalant (n=24, 35.8%), and lidocaine (n=22, 32.8%) were administered as first-line therapy for suppression of VTs. In the adjusted analyses, the odds ratio (OR) of switching to a different drug was significantly higher in the lidocaine group (OR 37.6, 95% CI 5.1-279, p<0.001) than in the amiodarone group, but not in the nifekalant group (OR 4.1, 95% CI 0.72-23.2, p=0.11). There was no significant difference in mortality rate in the lidocaine group (OR 1.67, 95% CI 0.40-6.95, p=0.48) or the nifekalant group (OR 1.11, 95% CI 0.15-4.85, p=0.89) compared with the amiodarone group. CONCLUSION Amiodarone and nifekalant are similarly effective in preventing VT recurrence, but their impact on survival rate is minimal. These data indicate that both nifekalant and amiodarone can be used for treatment of refractory VT.