Abstract 3905: Effects of Flecainide on Left Ventricular Pressure Gradient and Prognosis in Patients With Obstructive Hypertrophic Cardiomyopathy: A Comparison Between Flecainide and Disopyramide
It has been reported that disopyramide, a type I antiarrhythmic drug, may reduce left ventricular pressure gradient (LVPG) and improve symptoms in patients with obstructive hypertrophic cardiomyopathy (HCM). In some patients, however, disopyramide therapy should be withdrawn because of anti-cholinergic side effects such as dry mouth, constipation, and difficulty in micturition. Flecainide, other type I antiarrhythmic drug, has been approved on the United States for oral administration to treat patients with ventricular and supraventricular arrhythmias, without vagolytic side effects. However, it is still unclear whether flecainide is effective for improvement of LVPG and long-term prognosis in patients with obstructive HCM. In this study, therefore, we evaluate a long-term efficacy of flecainide for LVPG and mortality in patients with obstructive HCM, in comparison to disopyramide.
Methods: In 484 patients with HCM who were diagnosed and followed-up in our hospital, 143 (30%) patients had a significant LVPG at rest (≥30 mm Hg) with the use of continuous-wave Doppler echocardiography. Among these 143 obstructive HCM patients, 16 had managed with oral flecainide therapy and 26 had treated with oral disopyramide therapy. We analyzed LVPG before and after administration of flecainide or disopyramide, and HCM-related death (stroke death, heart failure death, or sudden death) rate in patients treated with flecainide or disopyramide during a mean follow-up of 10±7 years.
Results: The LVPG diminished from 75±36 to 41±35 mm Hg (p<0.005) after flecainide therapy, and from 76±25 to 35±25 mm Hg (p<0.001) after disopyramide therapy. A percent reduction of LVPG was 41±43% in patients with flecainide, which was similar to those with disopyramide, 51±35% (p=0.453). Furthermore, there was also no significant difference in HCM-related death rate between patients with flecainide and disopyramide (25% and 27%, p=0.875).
Conclusions: This study demonstrates that the improvement of LVPG and the incidence of HCM-related death in patients treated with flecainide were similar to those with disopyramide. Therefore, flecainide may be considered as useful alternatives for symptomatic obstructive HCM patients with disopyramide-induced vagolytic side effects.