The effects of intravenous levofloxacin on the QT interval and QT dispersion

Abstract

The QT dispersion (QT d ) is a non-invasive means of identifying those patients at an increased risk of developing sudden cardiac death (SCD). Although levofloxacin has a minimal effect on the QT c interval, isolated reports of QT prolongation, polymorphic ventricular tachycardia with a normal QT interval and TdP have been reported. The purpose of this study was to examine the effect of intravenous levofloxacin on the QT interval and QT d . Of the 50 patients who were deemed candidates to receive intravenous levofloxacin, 29 met the eligibility criteria and were enrolled in this study. A 12-lead ECG was performed before the initiation of levofloxacin (baseline), and on days 3 and 5. The QT c min , QT c max and the QT d were calculated. Measurements where made by two independent observers blinded to the patientsÕ clinical status. The QT d increased significantly on days 3 and 5 following the initiation of therapy [QT d (baseline) 33.3 ± 20 ms, QT d (day 3) 64.4 ± 31.3 ms (p = 0.023), QT d (day 5) 66.8 ± 20.3 ms, (p = 0.008)]. The increase in the QT d was significantly longer in men than women. Although women had a shorter baseline QT d compared to men, this did not achieve statistical significance. Intravenous levofloxacin was found to significantly increase the QT d , which was more pronounced in men compared to women. Its effect on the QT d may increase the risk of developing a potentially fatal ventricular arrhythmia. Therefore, care must be taken when prescribing this medication to patients with a pre-existing risk of developing SCD.

Antibiotic‐induced Cardiac Arrhythmias

“…Ciprofloxacin and levofloxacin did not prolong the APD90 at 100 lM in vitro studies [13,16]. They also did not prolong QTc intervals using recommended oral doses [27,32,33], but did so with intravenous or supratherapeutic doses in healthy volunteers [29] [34]. In postmarketing surveillance, the crude rates for the incidence of quinolone-induced cardiac arrhythmia per 10 million prescriptions were very low for these drugs, 5.4 cases for levofloxacin and 0.3 for ciprofloxacin [35].…”