Levofloxacin and Drug-Induced Long QT Syndrome (diLQTS): The Incidence and How to Prevent It

Levofloxacin is a fluoroquinolone antibiotic which is used widely in treating various infections. Despite this benefit, Levofloxacin has a cardiac side effect called drug-induced long QT syndrome (diLQTS), which is associated with Torsades de Pointes (TdP). In this study, our objective was to analyze the incidence of diLQTS associated with Levofloxacin use in Ahmad Dahlan Hospital Kediri. This study included patients who were admitted to Ahmad Dahlan Hospital Kediri from March-May 2019 and received Levofloxacin 500mg therapy once daily. An electrocardiogram was performed before and after initiation of therapy. Prolonged QTc was defined by heart rate-corrected QT ≥450ms for male and ≥470ms for female, calculated using Bazett formula; or if the prolongation of QT interval is >60ms from baseline. Acquired data were analyzed using Paired T-test. Of all 24 patients who received Levofloxacin, six patients developed long QTc. Two of which had >60ms difference from base ECG (p-value >0.05). No symptom of TdP was reported. The incidence of diLQTS associated with Levofloxacin use was 25%. Risk factor stratification and ECG monitoring should be done from the beginning of the therapy.