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Acute intravenous and long-term oral hemodynamic effects of encainide
Insights
Encainide, a Class IC antiarrhythmic, showed no significant adverse hemodynamic effects in patients with ventricular arrhythmias and heart failure. This new agent offers a favorable safety profile compared to other Class I drugs.
Area of Science:
- Cardiology
- Pharmacology
- Electrophysiology
Background:
- Complex symptomatic ventricular arrhythmias often coexist with left ventricular dysfunction and heart failure.
- Existing antiarrhythmic therapies may have significant hemodynamic side effects.
- Class IC antiarrhythmic agents represent a newer therapeutic option.
Purpose of the Study:
- To evaluate the short- and long-term hemodynamic effects of encainide.
- To assess the impact of encainide on left ventricular function and congestive heart failure status.
- To compare encainide's hemodynamic profile with other Class I antiarrhythmic agents.
Main Methods:
- Prospective study involving 25 patients with ventricular arrhythmias and left ventricular dysfunction.
- Nuclear ventriculography performed at baseline, during therapeutic encainide doses (75-300 mg/day), and after 6 months to 1 year.
- Exclusion of previous antiarrhythmic drugs for at least 3 days prior to baseline assessment.
Main Results:
- Encainide demonstrated no significant changes in heart rate, blood pressure, left ventricular ejection fraction, or volumes.
- No patient experienced worsening of congestive heart failure during encainide treatment.
- Published data suggest intravenous encainide has mild, dose-related cardiac depressant effects, comparable to other newer Class I agents.
Conclusions:
- Encainide exhibits a favorable short- and long-term hemodynamic profile in patients with complex ventricular arrhythmias and impaired left ventricular function.
- The drug appears safe for patients with New York Heart Association Class III or IV congestive heart failure.
- Encainide represents a potentially valuable therapeutic option with a comparable or improved hemodynamic safety profile versus other Class I antiarrhythmics.
Abstract:
The short- and long-term hemodynamic effects of encainide, a new class IC antiarrhythmic agent, were studied in 25 patients (mean age 61 +/- 11) with complex symptomatic ventricular arrhythmia and left ventricular dysfunction. Ninety-two percent had previous myocardial infarction and 8% had dilated cardiomyopathy. Seventy-five percent had congestive heart failure, class III or IV, according to the New York Heart Association. All patients underwent a nuclear ventriculogram performed at least 3 days after discontinuing previous antiarrhythmic drugs. Nuclear ventriculograms were repeated 1 to 6 weeks later while the patients were receiving therapeutic doses of encainide ranging from 75 to 300 [corrected] mg/day. Nuclear ventriculograms were also repeated after 6 months or 1 year of encainide therapy in 16 of these patients. Encainide did not have significant effects on heart rate, blood pressure, left ventricular ejection fraction, systolic or end-diastolic volumes. None of the patients showed a worsening of congestive heart failure during encainide therapy. These results compare favorably with those of other class I antiarrhythmic agents. A review of published reports on the hemodynamic effects of intravenous encainide shows it to have a mild but statistically significant dose-related depressant effect on cardiac function. This effect, however, appears to be no different from that of other newer class I agents.