Proarrhythmia, cardiac arrest and death in young patients receiving encainide and flecainide

Abstract

The potential for proarrhythmic responses to the class IC sodium channel-blocking drugs encainide and flecainide has not been well described in young patients. Therefore, data were retrospectively collected from 36 institutions regarding 579 young patients who were administered encainide or flecainide for treatment of supraventricular tachycardias (encainide 86 patients, flecainide 369 patients) or ventricular arrhythmias (encainide 21 patients, flecainide 103 patients) to assess the frequency of proarrhythmia, cardiac arrest and death during therapy (adverse events). The two drugs were similar in regard to efficacy (flecainide 71.4%, encainide 59.8%) and rate of proarrhythmic responses (flecainide 7.4%; encainide 7.5%). However, patients receiving encainide more frequently experienced cardiac arrest (encainide 7.5% vs. flecainide 2.3%, p less than 0.05) or died during treatment (encainide 7.5% vs. flecainide 2.1%, p less than 0.05). Detailed data were provided for 44 patients experiencing one or more adverse events. Patient age, previous drug trials, concomitant therapy and days of inpatient monitoring were similar for patients receiving encainide or flecainide. However, echocardiographic left ventricular shortening before treatment was lower among patients receiving encainide (0.23 +/- 0.09) than among those receiving flecainide (0.34 +/- 0.06, p less than 0.05). Plasma drug concentrations were rarely elevated. Cardiac arrest (12 patients) and deaths (13 patients) occurred predominantly among patients with underlying heart disease, particularly among patients receiving flecainide for supraventricular tachycardia (8.3% vs. 0.3%, p less than 0.001). Fifteen patients with an ostensibly normal heart and normal ventricular function experienced proarrhythmia during treatment for supraventricular tachycardia, but only 3 of the 15 had a cardiac arrest or died. The relatively high incidence of adverse events should be considered when contemplating treatment with encainide or flecainide, particularly among patients with underlying heart disease.

2015 ACC/AHA/HRS Guideline for the Management of Adult Patients With Supraventricular Tachycardia

“…Ablation of the accessory pathway(s) in high-risk patients was also examined in 1 RCT that enrolled 76 patients, showing that arrhythmic events (defined as symptomatic SVT, AF, and ventricular fibrillation in this study) occurred in 7% of patients who underwent ablation versus 77% who did not undergo ablation. 302 Another study that examined patients on the basis of whether an ablation was performed reported that none of the asymptomatic patients who had undergone ablation of the accessory pathway developed a malignant arrhythmia during 8 years of follow-up. The risk of complications with ablation ranged from 0.1% (complete heart block) to 0.9% (ablation-induced right bundle-branch block).…”

ACC/AHA/ESC 2006 Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death

“…Conversely, isolated ventricular ectopy is common in older postoperative congenital heart disease patients. In the absence of ventricular dysfunction or symptoms, isolated ventricular ectopy has minimal prognostic significance, and the risks of antiarrhythmic drug treatment can exceed any potential benefit (431). There remain many patients with simple or complex ventricular ectopy, with vague symptoms, or modest impairment of ventricular function who require individual judgment regarding the need for evaluation and treatment (432).…”

Atrioventricular Nodal Reentrant Tachycardia in Patients With Congenital Heart Disease

“…In addition, treatment with antiarrhythmic medications may have limited efficacy and higher incidence of side effects than in patients with structurally normal hearts. 10,11 Therefore, AVNRT Ablation in Congenital Heart Disease it is important to recognize the patterns of relationship of AVNRT with CHD and any difficulties in its transcatheter management and outcome. There have been previous case reports or case series on patients with specific forms of CHD, and, as well, a recent single-center retrospective study on this subject has been published.…”