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.