Background: The most critical adverse effects of class III drugs are marked QT prolongation and torsade de pointes. Even though intravenous amiodarone (iv-Amio) is a representative class III drug, it peculiarly inhibits both clinical ventricular tachycardia/fibrillation (VT/VF) and proarrhythmic effects.To test the hypothesis that iv-Amio homogeneously prolongs repolarization, we evaluated electrocardiographic changes before and during short-term amiodarone therapy, focusing closely on the ventricular dispersion of repolarization. Methods: Twenty-seven consecutive patients treated with iv-Amio for VT/VF as a first-line antiarrhythmic therapy were enrolled in this study. Twelve-lead electrocardiography was recorded before and during amiodarone therapy to evaluate the following electrocardiographic intervals: R-R, QRS, QT, QRS to T-peak (QTp), and T-peak to T-end (Tp-e; as an index of dispersion of repolarization). Repolarization indices were corrected to the heart rate by Bazett's method (QTc, c-QTp, c-Tp-e). Results: Amiodarone suppressed VT/VF in 19/27 (70%) patients without conferring any proarrhythmic effect. The QTc, c-QTp, and R-R interval were significantly prolonged during amiodarone (476. (plus or minus). 45. ms vs 511. (plus or minus). 45. ms, p<. 0.05; 338. (plus or minus). 40. ms vs 364. (plus or minus). 35. ms, p<. 0.05; 762. (plus or minus). 272. ms vs 870. (plus or minus). 189. ms, p<. 0.05; respectively), whereas the c-Tp-e and QRS durations did not change significantly (139. (plus or minus). 33. ms vs 145. (plus or minus). 41. ms, p=. 0.25; 96. (plus or minus). 20. ms vs 97. (plus or minus). 21. ms, p=. 0.33; respectively). Conclusions: Iv-Amio homogeneously prolongs repolarization and properly inhibits original VT/VF recurrence without inducing torsade de pointes.
Y., K., T., K., Y., A., R., Y., K., M., K., K., … S., M. (2015). Intravenous amiodarone homogeneously prolongs ventricular repolarization in patients with life-threatening ventricular tachyarrhythmia. Journal of Cardiology, 66(2), 161–167. Retrieved from http://www.embase.com/search/results?subaction=viewrecord&from=export&id=L604973280