Common antibiotic increases chances of heart failure

A new study has revealed that an antibiotic, which is widely used for treating common bacterial infections, is linked to an increased risk of heart death.

According to researchers, clarithromycin is prescribed to millions of people each year, and though the absolute risk is small and that prescribing practice should not be changed until results have been confirmed in an independent study.

the antibiotic belongs to a group of antibiotics known as macrolides. Macrolide antibiotics prolong the duration of electrical activity of the heart muscle (known as the QT interval) and are therefore thought to increase the risk of potentially fatal heart rhythm problems.

After adjusting for factors such as age, sex, baseline cardiac risk and use of other medication, ongoing use of clarithromycin was associated with a 76% higher risk of cardiac death compared with use of penicillin V. There was no increased risk of cardiac death with clarithromycin after treatment had ended.

The absolute risk difference was 37 cardiac deaths per 1 million courses with clarithromycin. No increased risk of cardiac death was found with ongoing or past use of roxithromycin.

The scientists said that their study expands on the available knowledge of the cardiac safety of macrolides, being the first large scale population based observational study to show significantly increased cardiac risk with clarithromycin and the relative cardiac safety of roxithromycin.

The authors also emphasized that the absolute increase in risk is small and should have limited, if any, effect on the prescribing practice in individual patients. However, they note, "clarithromycin is one of the more commonly used antibiotics in many countries and many millions of people are prescribed this drug each year; thus, the total number of excess (potentially avoidable) cardiac deaths may not be negligible."

The study was published in thebmj.com.