Oral flecainide therapy and myocardial pacing: preliminary data from a prospective multicenter registry

Abstract Background Antiarrhythmic drugs, class I are widely used for prevention of atrial fibrillation recurrence. However, previous studies found that these drugs could affect pacing thresholds among pacemaker recipients. Aim of the study: evaluate short -term effect on myocardial pacing following therapy with oral flecainide (200 mg/daily). Methods 45 consecutive pacemaker recipients were prospectively enrolled in a multicenter registry. These patients had preserved left ventricular ejection fraction, a dual chamber pacemaker with symptomatic sustained high-rate atrial fibrillation episodes and stable output atrial and ventricular thresholds. Patients were followed with ambulatory and/or remote monitoring. Results mean age was 74±1 years, 48% pts were male and AF burden was 8±16%. Pacemaker implantation was performed 3.9±0.3 year before study enrollment. Three (6%) out of 45 patients were excluded due to drug sided effects including dyspnea (n=1), diplopia (n=1) and toxicity during acute renal insufficiency (n=1). Flecainide treatment was associated with a significant reduction of atrial fibrillation burden (from 8±16% to 5±12%, p0.01). At 30 days follow-up since Flecainide starting therapy both atrial and ventricular sensing significantly decreased (3.6 ± 2.2 vs 3.4 ± 2.1mV p=0.01; 12.5±6.6 vs 11.8±6.3 mV p=0.01), while there was a slight increase of both atrial and ventricular capture thresholds (0.77±0.61V@0.4ms vs 0.80±0.42V@0.4ms p=0.01; 0.80±0.53V @0.4ms vs 0.83±0.33V @0.4ms p=0.01). No patient required pacemaker parameters reprogramming. Conclusions oral flecainide therapy among pacemaker recipients at 30 days follow-up seems to be safe and do not affect device function. Further studies with additional follow-up data are warranted.