QT prolongation associated with azithromycin/amiodarone combination

Administration of oral azithromycin, in addition to previously well-tolerat ed long-term amiodarone therapy, was associated with a marked prolongation of QT interval and increased QT dispersion, both substrates for life-threat ening ventricular tachyarrhythmia and torsades de pointes. This is a report of QT prolongation and increased QT dispersion associated with the use of azithromycin. The report assumes an added significance, in view of widespre ad empirical use of this antibiotic for the treatment of lower respiratory infections and belief of its safety in patients with cardiac diseases. Base d on the authors' experience, they would like to emphasize that the combina tion of azithromycin with other drugs known to prolong QT or causing torsad es de pointes be used with caution until the question of the proarrhythmic effect of azithromycin is resolved by further studies.