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Important differences between short- and long-term hemodynamic effects of amiodarone in patients with chronic
Insights
Short-term intravenous amiodarone has negative inotropic effects, requiring cautious use. Long-term oral amiodarone therapy is hemodynamically safe for patients with coronary artery disease and stable angina.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Amiodarone is used for antianginal effects.
- Hemodynamic effects of amiodarone vary with administration duration.
Purpose of the Study:
- Compare short-term (IV) vs. long-term (oral) amiodarone hemodynamics.
- Investigate amiodarone's antianginal hemodynamic mechanisms.
Main Methods:
- 10 patients with coronary artery disease and stable angina.
- Right heart catheterization and radionuclide angiocardiography at rest and exercise.
- Measurements before and after IV amiodarone and after 21 days of oral therapy.
Main Results:
- Acute IV amiodarone decreased ejection fraction, stroke index, and blood pressure; increased heart rate, filling pressures, and systemic vascular resistance.
- Long-term oral therapy reversed these effects, except for reduced heart rate and slightly elevated right atrial pressure.
- Exercise showed reduced heart rate, mean arterial pressure, and rate-pressure product after long-term therapy.
Conclusions:
- Acute IV amiodarone has significant negative inotropic effects, warranting cautious administration.
- Long-term oral amiodarone appears hemodynamically safe in patients with coronary artery disease and stable angina, even with mild left ventricular dysfunction.
Abstract:
To assess and compare the hemodynamic profile of short-and long-term amiodarone administration in the same set of patients and to investigate hemodynamic mechanisms responsible for the antianginal effect of this drug, 10 patients with documented coronary artery disease and stable angina pectoris were studied. Simultaneous right heart catheterization and equilibrium radionuclide angiocardiography were performed at rest and during exercise before therapy (control), after a 5 minute intravenous infusion of 7.5 mg/kg of amiodarone and after 21.0 +/- 4.3 days of peroral therapy (10 days 800 mg/day, 7 days 400 mg/day and then 200 mg/day). After acute drug administration, ejection fraction, stroke index and systolic blood pressure decreased, whereas heart rate, left and right ventricular filling pressures and systemic vascular resistance increased. These effects were reversed after long-term therapy; all measured values returned to control levels except for heart rate, which decreased below the control value, and right atrial pressure, which remained slightly elevated. Amiodarone drug levels decreased from 4.8 +/- 1.8 after intravenous infusion to 1.2 +/- 0.6 mg/liter after long-term therapy. After adjustment for hemodynamic changes at rest, there were still significant reductions in heart rate, mean arterial pressure and rate-pressure product during exercise. It is concluded that the marked negative inotropic effect of amiodarone administered acutely in the dose applied calls for cautious use of this drug when administered intravenously. In contrast, long-term oral amiodarone therapy seems hemodynamically safe, even in patients with moderately depressed left ventricular function.(ABSTRACT TRUNCATED AT 250 WORDS)