Hemodynamic effects of encainide in patients with ventricular arrhythmia and poor ventricular function.

Gated cardiac scanning was used to evaluate the hemodynamic effects of encainide in 19 patients (1 woman) with complex ventricular arrhythmia and depressed left ventricular (LV) function (ejection fraction less than 45%). Patients were 36 to 80 years old (average 61). All were candidates for long-term encainide therapy after having failed with currently available antiarrhythmics. Sixty-three percent had congestive heart failure before they received encainide. All were evaluated in the hospital before encainide therapy by a gated cardiac scan performed at least 3 days after discontinuing all antiarrhythmic drugs. Patients received oral encainide in doses of 75 to 200 mg. Gated cardiac scans were repeated 1 to 2 weeks later when an 80% reduction in frequency of premature ventricular complexes was observed on a 24-hour Holter recording. No patient had worsening of congestive heart failure during encainide therapy. Encainide did not significantly affect ejection fraction, which averaged 22 +/- 10% before and 25 +/- 14% (SD) after encainide (difference not significant [NS]). Other hemodynamic variables, including heart rate, blood pressure, stroke volume and end-diastolic volume, remained unchanged during encainide therapy. Digoxin blood levels in 10 patients averaged 1.04 +/- 0.43 before and 1.22 +/- 0.47 mg/ml (NS) during encainide therapy. Thus, encainide given orally in clinically effective doses does not appear to have significant hemodynamic effects in patients with ventricular arrhythmia and depressed LV function.