Evaluation of arrhythmic effects of clarithromycin usage in patients with acute coronary syndrome via new parameters of 12 lead electrocardiography

Aim: Clarithromycin is a widely used macrolide antibiotic with arrhythmic effects causing torsade de pointes by elongating QT interval. Clarithromycin was used to treat acute coronary syndrome. we aimed to determine the acute effects of short-term clarithromycin treatment on novel ECG parameters in patients with acute coronary syndrome.Material and Methods: The study we conducted in 2002 evaluated the effects of clarithromycin on endothelial functions and QTdispersion. We recently analyzed these patients’ ECGs performed before and one week after of 1000 mg/day clarithromycin treatment. We analyzed newly recognized parameters; Tp–e interval, Tp-e/QTc ratio, maximum QTc, minimum QTc, QTc dispersion values, P-maximum, P-minimum and P-wave dispersion to indicate the risk of atrial and ventricular arrhythmias. Results: There were 40 patients included where 20 were treated with clarithromycin and 20 not. In the clarithromycin group, mean age of the patients was 53.2±8.0 and in control group 58.9±11.6. Demographic characteristics of patients were similar. All ECG parameters were comparable prior to clarithromycin treatment. However, following therapy, all parameters including max QTc, min QTc, QTc dispersion, Tp-e interval, TP-e/QTc, Pmax, Pmin, and P-wave dispersion were statistically significantly higher in clarithromycin treated group (p<0.05 for each). Conclusion:Clarithromycin treatment not only affects QT parameters but also novel ECG parameters Tp–e interval and Tp-e/QTc ratio showing the risk of ventricular arrhythmias. It also affects P-wave parameters and dispersion that shows risk of atrial arrhythmias. We may conclude that clarithromycin treatment increases both ventricular and atrial arrhythmic risk during acute coronary syndromes.