Background: Paroxysmal atrial fibrillation (PAF) and paroxysmal supraventricular tachycardia (PSVT) leading to hemodynamic compromise are among the most common reasons for admission to the coronary care unit (CCU) and need prompt and efficient therapy. Direct current cardioversion is the therapy of choice, but if found contraindicated or unavailable some antiarrhythmic agents are usually given to restore sinus rhythm. Many of these drugs have obvious limitations, especially in patients with acute myocardial infarction and/or heart failure.
Hypothesis: The aim of the present study was to assess the safety and efficacy of intravenous amiodarone in the acute termination of PAF or PSVT refractory to other antiarrhythmic agents in a large group of patients consecutively admitted to our CCU.
Methods: In the present study, we evaluated the safety and efficacy of amiodarone given intravenously in 142 consecutive patients with PAF or PSVT lasting < 24 h. In 37% of patients no evidence of underlying heart disease which may have caused arrhythmias were defined. A median of two other antiarrhythmic agents given prior to the first amiodarone injection had been ineffective.
Results: Sinus rhythm was restored in 91 patients (64%) (65% in the PAF group and 61% in the PSVT group). The mean time to rhythm conversion was 5.5 +/- 6.1 h for patients with PAF and 1.2 +/- 1.2 h for patients with PSVT. The mean dose of amiodarone administered up to conversion was 340 +/- 220 mg for PAF and 220 +/- 105 mg for PSVT. Except for transient first-degree atrioventricular block in two patients, no adverse effects possibly related to amiodarone were observed (including proarrhythmia and incidence or aggravation of heart failure symptoms).
Conclusion: Amiodarone given intravenously for acute termination of supraventricular tachyarrhythmias is completely safe and seems effective. The results of this study, which is the largest ever made, indicate a need of randomized, controlled trials for the ultimate assessment of the efficacy of amiodarone in this clinical setting.