ORAL PROCAINAMIDE IN PATIENTS WITH STRUCTURAL HEART DISEASE AND REFRACTORY VENTRICULAR TACHYCARDIA

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There are limited therapeutic options for patients with structural heart disease and refractory ventricular tachycardia (VT) who have failed standard antiarrhythmic therapy. Even after VT ablation, recurrent VT is common; furthermore many patients are not candidates for VT ablation. Oral procainamide has a potential role in treatment of refractory VT but its efficacy and safety has not been evaluated in contemporary practice among patients with implantable cardioverter-defibrillator (ICDs). We conducted a retrospective cohort study between 2006-2013 at a tertiary referral center evaluating the use of oral procainamide in refractory VT. Patients were eligible if they had: 1) a left ventricular ejection fraction (LVEF) ≤ 40 %, 2) an ICD in place and 3) VT despite standard class-III AAD. Subjects were followed for 1 year for a primary outcome of appropriate ICD-shock or sustained VT below detection, VT ablation or heart transplantation/LVAD. The safety endpoints included adverse drug effects requiring discontinuation or exacerbation of heart failure. A total of 23 patients were identified. Mean age was 70±10 years and mean LVEF was 28±8%. The majority had ischemic cardiomyopathy (61%) and a secondary prevention ICD (83%). Forty-four percent had a history of VT-storm and 61% had prior VT ablation. Prior antiarrhythmic exposure included amiodarone in 87%, sotalol in 48% and mexiletine in 70%. Procainamide was introduced during hospitalization in 90% at a mean daily dose of 1821±562 mg. Recurrent appropriate ICD shock (39%) and VT storm (30%) were the most common indications. The composite primary outcome occurred in 12/23 (52%) at a median of 42 days (range 5-311). VT ablation for inefficacy occurred in 26% and recurrent ICD shock occurred in 22%. Safety endpoints occurred in 8/23 (35%) at a median of 63 days (range 5-258). Unplanned heart failure hospitalization occurred in 30% and adverse effects occurred in 17%. The overall mortality was 22% and 13% underwent transplantation/LVAD for primary heart failure. Oral procainamide has limited efficacy in highly morbid patients with refractory VT and previous failure of standard AAD. The high rate of treatment failure emphasizes the need for improved treatment options.