Long-term efficacy, safety and survival of patients with potentially lethal ventricular arrhythmias treated with low-dose amiodarone.

The effect of low-dose amiodarone was prospectively evaluated in 110 patients with potentially lethal ventricular arrhythmias and structural heart disease. The patient population had frequent and high-grade ventricular premature complexes (VPCs) (greater than or equal to 39/h) (multifocal, couplets, nonsustained ventricular tachycardia) refractory to conventional antiarrhythmic drugs. All patients had structural heart disease (coronary artery disease in 61%) and also a decreased left ventricular ejection fraction (LVEF) (43 +/- 16%). Patients were treated with low-dose amiodarone (maintenance dose of 275 +/- 102 mg/day.) During follow-up over a period of 15 +/- 11.5 months, 24 patients died of cardiac cause and, of these, 13 died of sudden death. Ventricular arrhythmia suppression at 1, 2, 3, and 4 years was 69%, 80%, 78%, 92% for VPCs, respectively; 96%, 90%, 92%, and 98% for couplets, respectively, and 57%, 57%, 97%, and 91% for nonsustained VTs (NVTs), respectively. Intolerable, reversible side effects requiring withdrawal were encountered in 24 patients (22%) (neurologic 10%, gastrointestinal 6.5%, skin 3.7%, proarrhythmic 0.9%, and cardiac 0.9%). Except for keratopathy (less than or equal to grade II) seen in all patients, the tolerable side effects were transient with dose adjustment. The study population was divided into two groups according to LVEF: Group A (LVEF greater than or equal to 40%, mean 54.4 +/- 9.7) and Group B (LVEF less than 40% mean, 27.7 +/- 7.2). The patients were further classified into responders (suppression of at least 70% of VPCs, 90% of couplets, and 100% of NVTs) and nonresponders. The difference in survival between responders and nonresponders in groups A and B was not statistically significant. Cumulative survival at 1, 2, 3, and 4 years was 90%, 85%, 85%, and 85%, respectively. In conclusion, low-dose amiodarone treatment: 1) Is effective in controlling VPCs and its complex forms and maintains long-term arrhythmia suppression. 2) The side effect profile compares favorably with conventional antiarrhythmics; severe side effects associated with high dosages (pulmonary, hepatic, neurologic, etc.) were rare or absent. 3) Amiodarone improves survival of patients with potentially lethal ventricular arrhythmias.