Amiodarone and torsades de pointes in patients with advanced heart failure

Amiodarone is considered to be safe in patients with prior QT prolongation and torsades de pointes taking class I antiarrhythmic agents who require continued antiarrhythmic drug therapy. However, the safety of amiodarone in advanced heart failure patients with a history of drug-induced torsades de pointes, who may be more susceptible to proarrhythmia, is unknown. Therefore, the objective of this study was to assess amiodarone safety and efficacy in heart failure patients with prior antiarrhythmic drug-induced torsades de pointes. We determined the history of torsades de pointes in 205 patients with heart failure treated with amiodarone, and compared the risk of sudden death in patients with and without such a history. To evaluate the possibility that all patients with a history of torsades de pointes would be at high risk for sudden death regardless of amiodarone treatment, we compared this risk in patients with a history of torsades de pointes who were and were not subsequently treated with amiodarone. Of 205 patients with advanced heart failure, 8 (4%) treated with amiodarone had prior drug-induced torsades de pointes. Despite similar severity of heart failure, the 1-year actuarial sudden death risk was markedly increased in amiodarone patients with than without prior torsades de pointes (55% vs 15%, p = 0.0001). Similarly, the incidence of 1-year sudden death was markedly increased in patients with prior torsades de pointes taking amiodarone compared with such patients who were not subsequently treated with amiodarone (55% vs 0%, p = 0.09). In patients with advanced heart failure, prior drug-induced torsades de pointes identifies heart failure patients at high risk for sudden death during therapy with amiodarone.