Antibiotic Tied to Slightly Higher Heart Attack Risk

Pneumonia patients who took azithromycin had slight increase in heart attack risk but not heart failure or arrhythmia risk

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) While some antibiotics may cure a bacterial infection, they also may be linked to less desirable health effects.

Azithromycin (brand name Zithromax or Z-Pak) is an antibiotic that may be used to treat pneumonia. Some patients who have taken azithromycin in the past have experienced heart problems that included irregular heartbeats and heart attacks.

A recent study of older people with pneumonia compared patients who took azithromycin to those who did not take azithromycin.

The researchers found that short-term survival was higher in those treated with azithromycin. The researchers also found a slight increase in heart attack risk, but no increase in risk of irregular heartbeat or heart failure in patients who were treated with azithromycin.

"Discuss medication side effects with your pharmacist."

Eric M. Mortensen, MD, MSc, from the VA North Texas Healthcare System and the University of Texas Southwestern Medical Center in Dallas, Texas, was the lead author of this study.

The study included more than 73,000 patients over the age of 65 who were hospitalized for pneumonia at Veterans Administration hospitals. The average age of the patients was 78 years, and 98 percent were male.

The researchers compared patients who were treated with azithromycin for their pneumonia to those who were treated with other antibiotics.

Dr. Mortensen and his team analyzed patient survival 30 and 90 days after taking antibiotics, as well as heart problems after 90 days. Some of the heart problems they looked for were heart failure, heart attack and irregular heartbeats.

Within 90 days of taking azithromycin, 17 percent of the patients died. In comparison, 22 percent of those who did not take azithromycin died.

Five percent of the people who took azithromycin had a heart attack, compared to 4 percent of those who took different antibiotics.

Within 90 days of taking medication, irregular heartbeats and heart failure occurred in 26 percent of the patients, regardless of which antibiotic they took.

Patients who took azithromycin had 24 percent lower odds of dying 30 days after taking the medication compared to non-users of azithromycin. The odds of dying in 90 days were 27 percent lower among patients who took azithromycin than among those who took other antibiotics.

The research team felt that the increased odds of survival, despite the increased risk of heart problems, might be due to the effect that azithromycin has on the immune system. The authors wrote that it is possible that the antibiotic reduced inflammation and that, in turn, increased survival.

The authors explained how their results could be interpreted in terms of harm or benefit to patients taking azithromycin. They wrote, "To put the balance of benefits and harms in context [...] the number needed to treat with azithromycin was 21 to prevent 1 death within 90 days, compared with a number needed to harm of 144 for [heart attack]. This corresponds to a net benefit of around 7 deaths averted for 1 nonfatal [heart attack] induced.”

The researchers noted some limitations of their study. For one, the VA patients in this study were 65 and older and mostly male, so the results may not apply to all patients. Furthermore, the researchers were unable to collect data on how long the patients were treated with azithromycin.

This study was published in the June 4 issue of JAMA.

Funding for the research was provided by the National Institute of Nursing Research.

Several co-authors disclosed conflicts of interest. Laurel A. Copeland, PhD, disclosed receiving grants from the National Institutes of Health, the Veterans Health Administration and Xenex Corporation.

Mark Metersky, MD, reported being a speaker/consultant for Pfizer until 2011. Christopher R. Frei, PharmD, MSc, received grants from Pfizer, Bristol-Myers Squibb, Ortho-McNeil Janssen and Forest. Pfizer is the manufacturer of Zithromax.

Review Date: 
July 2, 2014
Last Updated:
July 5, 2014