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Sudden death during empiric amiodarone therapy in symptomatic hypertrophic cardiomyopathy
L Fananapazir1, M B Leon, R O Bonow
1Cardiology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892.
Insights
Amiodarone improved symptoms and functional class in hypertrophic cardiomyopathy (HC) patients. However, it was associated with significant sudden death risk, especially early in treatment and in patients with ventricular tachycardia (VT).
Area of Science:
- Cardiology
- Pharmacology
Background:
- Hypertrophic cardiomyopathy (HC) is a genetic heart condition.
- Amiodarone is an antiarrhythmic drug.
- Conventional therapies for HC symptoms include calcium antagonists and beta blockers.
Purpose of the Study:
- To prospectively evaluate amiodarone's efficacy and safety in patients with hypertrophic cardiomyopathy (HC).
- To assess amiodarone's impact on symptoms, exercise tolerance, and survival in HC patients refractory to standard treatments.
Main Methods:
- Prospective evaluation of 50 HC patients treated with amiodarone (loading and maintenance doses).
- Assessment of New York Heart Association (NYHA) functional class and treadmill exercise duration.
- Holter monitoring for ventricular tachycardia (VT) and radionuclide angiography for left ventricular filling rate.
Main Results:
- Amiodarone significantly improved NYHA functional class and exercise duration.
- Eight patients died (7 suddenly) during a mean follow-up of 2.2 years; 6 sudden deaths occurred within 5 months.
- Patients with VT had significantly worse survival rates (61% at 2 years) compared to those without VT (97%).
- A decrease in left ventricular peak filling rate within 10 days of amiodarone therapy was linked to subsequent sudden death.
Conclusions:
- Amiodarone can improve symptoms and exercise capacity in HC patients.
- Despite potential benefits, amiodarone carries a significant risk of sudden death, particularly early in treatment and in patients with VT.
- Monitoring left ventricular filling rate may help identify patients at higher risk for sudden death during amiodarone therapy.
Abstract:
Amiodarone is reported to improve symptoms and to prevent sudden death in patients with hypertrophic cardiomyopathy (HC). Amiodarone treatment (loading dose 30 g given over 6 weeks; maintenance dose 400 mg/day) was prospectively evaluated in 50 patients with HC in whom the drug was initiated because of symptoms refractory to conventional drug therapy (calcium antagonists and beta blockers). Twenty-one (42%) patients had ventricular tachycardia (VT) during Holter monitoring. Amiodarone significantly and often markedly improved the patients' New York Heart Association functional class status (from 3.3 to 2.7 at 2 months, p less than 0.001) and treadmill exercise duration (p less than 0.001). Eight patients, however, died (7 suddenly) during a mean follow-up period of 2.2 +/- 1.8 years. Of the 7 sudden deaths, 6 occurred within 5 months of initiation of treatment. The 6-month and 1- and 2-year survival rates were 87, 85 and 80%, respectively. The survival rate of patients with VT was significantly worse than that of patients without VT (61 vs 97% at 2 years; p less than 0.01). Sudden death occurred despite abolition of VT on Holter monitoring. Amiodarone increased left ventricular peak filling rate by radionuclide angiography in 20 of 33 patients (61%) (p less than 0.01). Decrease in peak left ventricular filling rate within 10 days of amiodarone therapy (8 of 33 patients) was associated with subsequent sudden death (p less than 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)