The clinical significance of QT prolongation induced by antimicrobials: a literature review and case series

Macrolides and fluoroquinolones are the most widely used antimicrobials worldwide. However, there is still no definite position of the scientific community regarding their ability to lengthen the QT interval and to cause life-threatening arrhythmias, particularly torsades de pointes ventricular tachycardia. We studied the literature data in order to determine the most relevant antimicrobial drugs capable of prolonging the QT interval and to assess the risk factors for QT prolongation. The risk of clinically significant prolongation of QT was increased in patients treated with azithromycin and clarithromycin among macrolide antibiotics, levofloxacin and moxifloxacin among fluoroquinolones and voriconazole and fluconazole among azoles. The risk of arrhythmias was higher with the combined administration of these drugs. Cardio-vascular diseases, hypokalemia, hypomagnesemia, initially prolonged QT interval, old age and female gender were the risk factors for QT prolongation. We present 16 cases of QT prolongation that occurred during treatment with antimicrobial drugs (levofloxacin, moxifloxacin, azithromycin and fluconazole) from 2017 to 2022. Rhythm disorders, including ventricular arrhythmias, developed in 87.5% of patients with documented prolongation of the QT interval. The average prolongation of the QT interval was 127.0 ms in men and 98.2 ms in women and was observed on average on 4.4 and 5.4 days of treatment, respectively. The presence of risk factors and concomitant therapy should be taken into account when prescribing antimicrobials that prolong the QT interval. Regular ECG monitoring before and during antimicrobial therapy is recommended. An online resource can be used to assess the risk of QT prolongation and ventricular arrhythmias.

Key words

QT prolongation, Torsades de Pointes, fluoroquinolones, macrolides, antifungal drugs.