The Food and Drug Administration (FDA) warned on March 12th, 2013 that "Health care professionals should consider the risk of fatal heart rhythms with azithromycin when considering treatment options for patients who are already at risk for cardiovascular events”.
However, other broad spectrum macrolide antibiotics closely related in similar class, erythromycin and clarithromycin have already shown an increase risk of serious ventricular arrhythmias and associated with sudden cardiac death before such warning about azithromycin.
The New England Journal of Medicine has published the original study article in May'2012. http://www.nejm.org/doi/full/10.1056/NEJMoa1003833
Summary and Interpretation:
The study actually found a tiny increased risk in patients taking azithromycin. How tiny? Compared to taking amoxicillin, taking azithromycin contributed 47 additional cardiovascular deaths per 1 million antibiotic courses. That’s one extra death per 21,276 courses. If you took 5-day azithromycin courses continuously, it would take 291 years to take that many courses of antibiotics. That’s a much slower way to die than, say, hemlock.
All patients did not have the same risk of having a fatal heart rhythm abnormality. Older patients, patients taking medications for heart rhythm abnormalities, and patients with heart disease, certain EKG abnormalities, and certain electrolyte abnormalities were at greater risk of this side effect. The patients at highest risk face one additional death every 4,100 courses of antibiotics, while those at lowest risk have one additional death every 110,000. These are very, very small risks.
So doctors should try to avoid all macrolides in high risk patients. But patients should probably forget the whole thing and avoid azithromycin for a different reasons such as risk of C. difficile infection and the risk of antibiotic resistance is much greater than the tiny risk of a fatal rhythm abnormality.
Posted By: Ankit Bhalodia, PharmD Candidate 2014