EFFECTS OF FLECAINIDE AND PROPAFENONE ON SYSTOLIC PERFORMANCE IN SUBJECTS WITH NORMAL CARDIAC-FUNCTION

Flecainide and propafenone are effective in suppressing both ventricular and supraventricular tachyarrhythmias, but their efficacy is often limited by dose-related side effects. This study was performed to evaluate noninvasively the effects of intravenous flecainide and propafenone on left ventricular systolic function indices in a selected population of 40 subjects (28 men and 12 women; mean age, 25 years) with normal cardiac structure and performance. Echocardiographic indexes of global systolic pump function (ejection fraction [EF] and percentage of fractional shortening [percent FS]) as well as monodimensional parameters of the interventricular septum (IVS) and left ventricular posterior wall (PW) contractility (percent systolic thickening [percent th] and systolic excursion [ex]) were assessed in all subjects at baseline, immediately after, and in the early recovery (15 min) after randomized injection of either flecainide or propafenone. Heart rate and blood pressure did not significantly change after both drugs. A significant increase (p<0.001) in left ventricular systolic internal diameter was observed after both flecainide and propafenone; simultaneously a significant decrease of percent FS (p<0.001), EF (p<0.001), PW percent thickening (th) (p<0.001), and PWex (p<0.001 after flecainide and p<0.01 after propafenone) was recorded. These changes were comparable and promptly reversible. In analyzing individual data, a marked systolic dysfunction was observed in two patients after intravenous flecainide (percent FS from 37 percent to 17 percent and from 42 percent to 13 percent; EF from 55 percent to 40 percent and from 65 percent to 35 percent, respectively) and in one patient after intravenous propafenone (percent FS from 30 percent to 15 percent; EF from 58 percent to 35 percent). We conclude that both intravenous flecainide and propafenone exhibit mild negative inotropic effects leading to a moderate and reversible reduction of left ventricular systolic performance; however, in some cases, a dramatic impairment of systolic pump function may occur, suggesting careful use of both drugs as first-line agents also in normal subjects; finally, the true incidence of this deleterious effect is still unknown.