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Exploring the minimal dose of amiodarone with antiarrhythmic and hemodynamic activity
J J Mahmarian1, F W Smart, L A Moyé
1Department of Medicine, Baylor College of Medicine, Houston, Texas 77030.
Insights
This pilot study suggests low-dose amiodarone (100 mg/day) effectively reduces ventricular arrhythmias and improves heart function in patients with nonsustained ventricular tachycardia. Further research is warranted to confirm these promising antiarrhythmic and hemodynamic benefits.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Amiodarone is used for secondary prevention in post-myocardial infarction patients with ventricular ectopy or tachycardia.
- The optimal low dose of amiodarone for antiarrhythmic and hemodynamic effects requires further investigation.
Purpose of the Study:
- To explore the lowest effective dose of amiodarone for antiarrhythmic and hemodynamic activity.
- To evaluate the efficacy of low-dose amiodarone in patients with nonsustained ventricular tachycardia.
Main Methods:
- A 3-month, randomized, double-blind, placebo-controlled pilot study.
- 48 patients with nonsustained ventricular tachycardia were randomized to placebo, amiodarone 50 mg/day, or amiodarone 100 mg/day.
- A loading dose of amiodarone (422 mg/day) was administered for the first week.
Main Results:
- Amiodarone 100 mg/day significantly reduced ventricular premature complexes, couplets, and nonsustained ventricular tachycardia runs (p < 0.01).
- Total suppression of nonsustained ventricular tachycardia was observed in 10/14 patients on 100 mg/day amiodarone versus 4/15 on placebo (p = 0.021).
- Left ventricular ejection fraction improved by >= 7% in 11/29 amiodarone patients versus 1/15 placebo patients (p = 0.02), with significant increases in ejection fraction, stroke volume index, and decreases in end-systolic volume index in responders.
Conclusions:
- Low-dose amiodarone (100 mg/day) demonstrates significant antiarrhythmic efficacy in patients with nonsustained ventricular tachycardia.
- Amiodarone at 100 mg/day may improve hemodynamic function, including ejection fraction, in a subset of patients.
- This pilot study supports further investigation into low-dose amiodarone for managing ventricular arrhythmias and heart failure.
Abstract:
Amiodarone in doses of 200 to 400 mg/day has shown promise in secondary prevention trials for reducing mortality in patients surviving myocardial infarction who have complex ventricular ectopy or nonsustained ventricular tachycardia, or both. In an attempt to explore the lowest dose of amiodarone with antiarrhythmic and hemodynamic activity, we studied 48 patients (mean age 53 +/- 11 years, ejection fraction 23 +/- 9%, clinical heart failure in 85%) with nonsustained ventricular tachycardia. This was a 3-month, randomized, parallel, double-blind pilot study comparing placebo (n = 16) with amiodarone 50 mg/day (n = 15) and 100 mg/day (n = 17). Patients randomized to amiodarone received a mean loading dose of 422 mg/day for the first study week. At the end of the 12 weeks, amiodarone (100 mg) significantly reduced ventricular premature complexes (177 +/- 64 to 98 +/- 38/hour), couplets (8 +/- 3 to 4 +/- 2/hour), and runs of nonsustained ventricular tachycardia (13 +/- 7 to 3 +/- 2/day), all p < 0.01 versus baseline. In addition, 10 of 14 patients taking 100 mg/day had total suppression of nonsustained ventricular tachycardia compared with 4 of 15 taking placebo, p = 0.021. Left ventricular ejection fraction improved by > or = 7% (absolute) in 11 of 29 patients taking amiodarone as compared with only 1 of 15 placebo patients (p = 0.02). In these 11 patients with the greatest measurable hemodynamic improvement, amiodarone significantly increased ejection fraction (21 +/- 7% to 33 +/- 11%, p < 0.01), stroke volume index (28 +/- 9 to 40 +/- 7 ml/m2, p < 0.01) and decreased end-systolic volume index (116 +/- 48 to 92 +/- 44 ml/m2, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)