A. Gabin, A. Fawaz, N. A. Freedberg, N. Schwartz, M. Elias, W. Saliba, L. H. Goldstein; Haemek Medical Center, Afula, Israel

BACKGROUND: Large data based studies have reported excess cardiovascular mortality in high risk patients treated with azithromycin, but whether or not azithromycin causes QT prolongation remains controversial. In this study we aimed to examine the association between azithromycin treatment and QT prolongation in a cohort of hospitalized patients with community acquired pneumonia (CAP).
METHODS: 122 hospitalized patients with CAP were enrolled in the study. We compared the baseline QTc with daily post antibiotic QTc. Other risk factors for QT prolongation such as medication or electrolyte abnormalities were recorded
RESULTS: Ninety (73.8%) patients were treated with Azithromycin (usually together with ceftriaxone), and 32 (26.2%) patients were treated with other antibiotics (Ampicillin-clavulanate, Chloramphenicol, Doxcycline, or Ceftriaxone). 72.1% (88) of patients experienced QT lengthening. 72.7% of the patients with QT lengthening had a normal baseline QTc. Azithromycin was not associated with the post antibiotic QTc. The only variable associated with wide (pathological) post antibiotic QTc was the pneumonia score. For every 10 point increase in the pneumonia score the odds for a pathological post antibiotic QTc was 1.249 (95% CI:1.050-1.486). Subgroup analysis of patients with non-pathological baseline QTc revealed that the only variable associated with pathological post antibiotic QTc was a previous stroke.
CONCLUSION: Azithromycin treatment is not associated with QT prolongation in patients with severe CAP, although a substantial percent of hospitalized CAP patients develop QT prolongation and pathological QTc regardless of the antibiotic used, especially patients with a previous stroke or higher pneumonia score.