Cardiac risk of concomitant levofloxacin with amiodarone

Cardiac risk of concomitant levofloxacin with amiodarone

Introduction:

Levofloxacin, a commonly used quinolone antibiotic, and amiodarone, an antiarrhythmic agent, are both known to prolong the QT interval. Several case reports have been published describing the reality of the dangerous pro-arrhythmic characteristics due to the drug combination but no studies have been completed in a real-world, clinical setting.

Objectives:

The purpose of this study was to investigate the impact of the concomitant usage of levofloxacin and amiodarone on QT interval prolongation and the occurrence rate of cardiac events. 

Study Design:

A restrospective cohort study of all patients treated with levofloxacin and amiodarone when admitted to the medical center from January 1, 2012 to August 31, 2015. Only patients with available electrocardiograms before and after treatment were eligible for inclusion. Inclusion was limited to adult patients (≥18 years of age). Patients on acute amiodarone therapy immediately upon admission were excluded from the study. Patients were stratified into two groups: concomitant usage of levofloxacin plus amiodarone and non-concomitant usage of levofloxacin and amiodarone.

Methods:

The primary outcome was change in QTc interval from baseline to post-treatment. The change in QTc interval was compared between groups. All data were summarized using descriptive and inferential statistics.

Results:

A total of 107 patients were included in the preliminary analysis, 76 of which received concomitant levofloxacin and amiodarone. A mean change from baseline in QTc interval of 30.60 milliseconds (ms) for the concomitant group and -0.50 ms for the non-concomitant group. The mean difference between the two groups was 31.10 milliseconds (p<0.001; 95% confidence interval, 18.52 ms, 43.69 ms).There were no deaths in the study.

Conclusions:

The results from the analysis indicate that there is a statistically significant increase in QTc interval in patients given concomitant amiodarone and levofloxacin in comparison to patients given either medication alone.