Long-term low-dose amiodarone therapy in the management of ventricular and supraventricular tachyarrhythmias

Objective:To evaluate the efficacy and acceptability of low-dose amiodarone therapy in the long-term management of supraventricular and ventricular tachyarrhythmias.Methods:124 pa- tients with symptomatic drug refractory or life-threatening arrhythmias managed with low dose oral amio- darone therapy over a 10-year period was analyzed retrospectively.Loading doses of amiodarone 600 mg daily for 1 week were administered for supraventrieular arrhythmias and 600-1200 mg daily for 2 weeks for ventricular arrhythmias.Maintenance daily doses were 194±48 and 206±55 mg,respectively.Mean treat- ment duration was 32±28 months,with 326.3 patient years of therapy.Results:Of 39 patients with sustained ventricular tachyarrhythmias,the actuarial incidence of satisfactory arrhythmia control(absence of sudden cardiac death or nonfatal arrhythmia recurrence)was 78% at 1 year and 71% at 2 years.Satisfac- tory control of supraventrieular arrhythmias(mean ventricular rate100bpm with significant symptomatic improvement for sustained atrial arrhythmias and1 attack per year for paroxysmal atrial or atrioven- tricular arrhythmias)was achieved in 73,65,and 62 % of patients at 1,2,and 3 years,respectively.The cu- mulative incidence of amiodarone related adverse effects was 5.8 per 100 patient years,with drug with- drawal required in 12 patients(9.7%).Fifteen patients had thyroid dysfunction,2 had hepatic toxicity,and 1 developed nonfatal pulmonary fibrosis.Overall,the incidence of successful use of amiodarone(satisfactory arrhythmia control and freedom from side effects)was 67,59,and 53% at 1,2,and 3 years,respectively. Conclusion:The efficacy of low-dose amiodarone therapy in the management of serious ventricular and supraventricular arrhythmias would be similar to those achieved with higher doses,but with a much more acceptable side effect profile.