The Potential for QT Interval Prolongation with Chronic Azithromycin Therapy in Adult Cystic Fibrosis Patients

Sean N. Avedissian, Nathaniel J. Rhodes, Tien M.H. Ng, Adupa P. Rao, Paul M. Beringer

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Introduction: Oral azithromycin (AZM) has been shown to reduce airway inflammation and disrupt biofilm formation. However, chronic AZM therapy may result in QT interval (QTc) prolongation. Objectives: The goals of this study were twofold: (i) to characterize the risk of QTc prolongation in adult patients with cystic fibrosis (CF) receiving AZM and other potential QTc-prolonging agents, and (ii) to describe and capture the number of potential QTc-prolonging agents patients with CF are prescribed. Methods: A retrospective study was conducted over a 3-year period in an adult CF center. QTc values were recorded from electrocardiograms. Univariate and multivariate analyses were conducted. Standard QTc prolongation definitions (males ≥ 450 msec, females ≥ 470 msec) were used. Results: A total of 89 adult CF patient's records were reviewed. Sixty-eight patients received chronic AZM therapy. Two male patients had prolonged QTc, but only 1 received chronic AZM therapy. The median QTc interval between patients receiving and not receiving AZM was not significantly different (405 [interquartile range, IQR: 388–425] vs 394 [IQR: 384–413] msec, respectively, p=0.14). Also, the QTc interval for patients taking chronic AZM 500 mg Monday/Wednesday/Friday or 250 mg daily was not significantly different (401 [IQR: 383–419] vs 409 [IQR: 394–427] msec, respectively, p=0.48). When stratified by the number of QTc-prolonging medications (AZM vs no AZM), there was no significant difference in median QTc values between patients receiving zero to ≥ 5 QTc-prolonging medications. Conclusion: An association between chronic AZM therapy and longer QTc intervals or significant QTc prolongation was not shown.

Original languageEnglish (US)
Pages (from-to)718-723
Number of pages6
Issue number6
StatePublished - Jun 2019
Externally publishedYes


  • QT interval prolongation
  • azithromycin
  • cystic fibrosis

ASJC Scopus subject areas

  • Pharmacology (medical)


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