Does azithromycin prolong QT Interval in ICU patients?

Use of azithromycin among patients admitted to the intensive care unit (ICU) does not appear to contribute significantly to the increase in QTc interval, a study has shown.

Some 241 ICU patients received doses of either azithromycin or doxycycline intravenously between 1 June 2019 and 31 March 2020. Of these, 93 were included in the final analysis: 75 in the azithromycin group and 18 in the doxycycline group.

The azithromycin group had a baseline QTc of 449 (95 percent confidence interval [CI], 438–461), and the 72-hour QTc was 442 (95 percent CI, 427–453). The average change in QTc was –4 (p=0.14). No statistically significant difference was observed in QTc interval change between the two treatment arms.

“Based on these results, for the majority of patients receiving azithromycin, QTc prolongation is not likely a major concern,” the investigators said. “However, caution may still be warranted in patients considered high risk.”

This single-centre, retrospective chart review was conducted in ICU patients, with change in QTc from 48 to 72 hours after antibiotic initiation as the primary outcome. The investigators used ANOVA matched comparison to analyse the change in QTc.

“Azithromycin is a commonly prescribed antibiotic included in many first-line regimens for pneumonia,” the investigators said. “Azithromycin also carries an FDA warning for increased risk for abnormal cardiac electrical activity, including QTc prolongation.”