Clinical study of amiodarone-associated torsade de pointes in Chinese people

Objects: Amiodarone-associated torsade de pointes (Tdp) has been reported increasingly in China in recent years. In this study, we made clinical analysis of amiodarone-associated Tdp in Chinese people. Methods: Two major Chinese medical databases were searched to identify articles published during the last 26 years that presented data on amiodarone-associated proarrhythmic events. The articles were divided into two categories: case reports and observational studies. Results: Fifty-two Chinese-language case reports with 98 patients and 2 patients registered in our hospital, total 100 patients about amiodarone-associated Tdp, were enrolled in the study. Amiodarone-associated Tdp occurred more frequently in females (68.0%, 68/100). The major primary disease of females was rheumatic heart disease (40.7%, 24/59), while that of males was coronary heart disease (45.8%, 11/24). In most patients, Tdp occurred repeatedly and terminated in 24-48 hours. Some Tdp worsen to ventricular fibrillation and caused 19 patients' death (mortality rate 21.8%, 19/87). Known predisposing factors to the development of Tdp, such as heart failure, hypokalemia, drugs combination, and bradyarrhythmia, existed in many cases. Tdp also occurred in six patients (4 females, 2 males) without any known predisposing factors except QTc interval prolongation. Fourteen observational studies each reported data from at least 100 patients who were treated with amiodarone for at least 1 month. Of 2,354 patients included in these studies, 455 patients exposed to amiodarone were reported to have proarrhythmic events (an overall incidence of 19.3%), while only 4 patients were reported to have Tdp or ventricular fibrillation (an incidence of 0.17%). Conclusions: In conclusion, approximately one-fifth of the patients have amiodarone-induced proarrhythmic events, while the incidence of Tdp or ventricular fibrillation is remarkably low. Amiodarone-associated Tdp occurred more frequently in Chinese females. Known predisposing factors for occurrence of Tdp prevailed in Chinese patients. QTc interval prolongation may be an independent risk factor of amiodarone-associated Tdp.