Comparison between oral procainamide and mexiletine for the treatment of recurrent and refractory ventricular tachyarrhythmias

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background The antiarrhythmic therapy of recurrent ventricular arrhythmias in patients having undergone catheter ablation and in whom amiodarone and/or beta blockers were ineffective or contraindicated, is a controversial issue. Purpose The present study sought to compare the efficacy and tolerability of oral procainamide and mexiletine in patients with recurrent ventricular arrhythmias, when the standard therapy strategy failed. Methods All patients with an implantable cardioverter defibrillator (ICD) treated with oral procainamide or mexiletine for recurrent ventricular tachycardia (VT) or ventricular fibrillation (VF) in 2 Cardiology Divisions between January 2010 and January 2020 were enrolled. The patients were divided in group A (oral procainamide) and group B (mexiletine) and the 2 groups were compared to each other. The primary endpoint was the efficacy of therapy; the secondary endpoint was the discontinuation of therapy. All the events occurring during procainamide or mexiletine treatment were compared with a matched duration period before the initiation of the therapy. Antiarrhythmic therapy was considered effective when an ≥80% reduction of the sustained ventricular arrhythmias (SVA) burden recorded by the ICD was achieved. Results A total of 68 consecutive patients (61 males, 89.7%; mean age 74 ± 10 years) were included in this retrospective analysis. In 27 (39.7%) patients catheter ablation of VT was attempted before therapy initiation. A concomitant therapy with amiodarone was present in 25 (36.8%) patients. The mean dose of procainamide was 1207±487 mg/die. The mean dose of mexiletine was 576±66 mg/die. After a median follow-up of 19 months, 38 (56%) patients had a significant reduction in the SVA burden. After multivariable adjustment (Table 1), therapy with procainamide was independently associated with an almost 3-fold higher efficacy on VA suppression compared to mexiletine (HR 2.54, 95% CI 1.06-6.14, p=0.03). Similar results (HR 2.89, 95% CI 1.26-6.62, p=0.01) were found after adjustment using inverse probability weighting by a propensity score including age, gender, left ventricular ejection fraction, ischemic heart disease and concomitant amiodarone therapy. Only 3 patients (9%) treated with procainamide presented severe side effects (dyspnea or hypotension) requiring discontinuation of therapy against 6 patients (18%) treated with mexiletine who interrupted therapy because of severe side effects (p=0.47). Conclusions Compared to mexiletine, oral procainamide has a higher efficacy for the treatment of recurrent and refractory VAs and shows a good profile of tolerability Table 1. Multivariable Cox Proportional Hazards Analysis of Baseline Covariates in Relation to effective VAs suppression.