June 17 (UPI) -- People taking the commonly prescribed antibiotic azithromycin were nearly twice as likely to die from a heart attack, stroke or other cardiovascular event than users of the antibiotic amoxicillin, an analysis published Wednesday by JAMA Network Open found.
Although azithromycin has been linked with irregular heartbeat and other cardiac-related side effects, the findings do not necessarily suggest that it causes death in people with cardiovascular problems or who are at risk for heart health events, the authors said.
"Though the relative increase in risk was large, the absolute increase in risk was very small -- approximately 13 additional cardiovascular deaths per 1 million azithromycin prescriptions," study co-author Dr. Jonathan G. Zaroff, told UPI.
"These small risks need to be weighed against the well-established benefits of azithromycin for a broad range of infections, including serious infections such as pneumonia," said Zaroff, a cardiologist with Kaiser Permanente in California.
Azithromycin received approval from the U.S. Food and Drug Administration in 2002. Since then, it has been used to treat a variety of infections, including those that affect the lungs and sinuses.
More recently, the drug has been explored for use in the treatment of COVID-19, the disease caused by the new coronavirus, SARS-CoV-2.
Studies to date have evaluated it as part of a regimen that includes the anti-malarial drug hydroxychloroquine, but many of these trials have been discontinued due to heart-related side effects. In addition, the combination's effectiveness remains a subject for debate among researchers.
For the study, researchers reviewed data on more than 7.8 million people who were administered antibiotics over a 17-year period. More than 1.7 million of the prescriptions involved azithromycin, the researchers said.
Most of those who died from a cardiovascular event after taking the drug did so within five days of exposure. Azithromycin users were also more than twice as likely to die from other causes not related to heart disease, the researchers found.
In addition, other health conditions -- referred to as comorbities -- may contribute to "increased risk of cardiovascular or non-cardiovascular death," they said.
"For azithromycin and related antibiotics such as clarithromycin, prior reports have indicated that these drugs can alter the normal flow of electricity within the heart muscle and increase the risk of life threatening arrhythmia or irregular heartbeats," Zaroff said.
"Though [we] did report some deaths that were sudden and likely related to arrhythmia, more of the cardiovascular deaths were due to other heart conditions such as heart attack and heart failure, and there is no known theory to explain why azithromycin exposure would cause a heart attack or worsen heart failure," he said.