Use Of Mexiletine for Recurrent Ventricular Tachycardia in Patients with Severe Left Ventricular Systolic Dysfunction: A Retrospective Observational Study

Abstract

Background: Recurrent ventricular tachycardia (VT) is a major therapeutic challenge in patients with severe left ventricular systolic dysfunction (LVSD), particularly when arrhythmias persist despite contemporary heart failure therapy, implantable cardioverter-defibrillator (ICD) therapy, and/or catheter ablation. Mexiletine is an oral class IB sodium-channel blocker that remains an adjunctive option in selected patients with refractory ventricular arrhythmias. This study evaluated its effectiveness and safety in patients with recurrent VT and severe LVSD.

Methods: This retrospective observational study was conducted in the Department of Cardiology at Sri Ramachandra Medical College & Research Institute, Chennai. Records of 200 adults with VT and left ventricular ejection fraction (LVEF) ≤35% who received mexiletine as part of routine clinical care were reviewed. Demographic, clinical, echocardiographic, arrhythmic, treatment, and adverse-event data were extracted. VT episodes and ICD shocks before and after mexiletine initiation were compared using paired analyses, with statistical significance defined as p<0.05.

Results: The mean age was 60.69±12.63 years and 57% of participants were male. Ischemic cardiomyopathy was the most frequent underlying etiology (40%), followed by dilated cardiomyopathy (36%) and post-myocardial infarction left ventricular dysfunction (24%). Mean LVEF was 26.29±5.20%. The mean baseline VT burden was 15.14±6.87 episodes compared with 4.65±3.27 episodes after treatment (p<0.0001). Mean ICD shocks decreased from 4.36±2.53 to 2.38±2.01 (p<0.0001). The mean percentage reduction in VT episodes was 68.75±15.39%. The mean mexiletine dose was 433.96±170.16 mg/day and mean follow-up was 8.16±3.20 months. No adverse effects were documented in 66% of patients; tremor was the most frequent reported adverse effect (22%), followed by nausea (7%), gastrointestinal upset (3.5%), and dizziness (1.5%).

Conclusion: In this single-center retrospective cohort of patients with severe LVSD and recurrent VT, mexiletine use was associated with substantial reductions in VT episodes and ICD shocks and was generally well tolerated. Because the study lacked a control group and nearly half of the cohort received concomitant amiodarone, the findings support mexiletine as an adjunctive option rather than establishing an independent causal treatment effect.