Azithromycin Exposure in a 10-Day Window of Myocardial Infarction and Short- and Long-Term Outcomes

The U.S. Food and Drug Administration warned in 2012 that azithromycin (AZM) can cause potentially fatal irregular heart rhythm, particularly in patients with known cardiac risk factors.

This study aimed to examine cardiac and hospital readmission outcomes associated with AZM exposure near the time of a myocardial infarction (MI).

This was a retrospective cohort study using Merative MarketScan databases examining adult inpatients admitted with MI from January 1, 2010 to December 31, 2017. Patients with AZM exposure 7 days pre-MI to 3 days post-MI were compared to unexposed controls. Time to subsequent MI and incident heart failure (HF) were examined up to 5 years post-MI using Cox models. All-cause, MI-related, MI and sequelae-related readmissions and incident HF diagnosis were examined 30 days post-MI using logistic regression.

There were 18,066 eligible patients in the full cohort (AZM, N = 3,011), and the HF-free at baseline cohort included 9,180 patients (AZM, N = 1,530). Probability of subsequent MI up to 5 years post-MI was 15.3% in the AZM group vs 9.7% in control (HR: 1.41 [95% CI: 1.10-1.81], P = 0.0076). Probability of incident HF was 39.8% in the AZM group vs 35.5% in control (HR: 1.12 [95% CI: 0.91-1.39], P = 0.2795). Odds of all 4 30-day outcomes were significantly higher in the AZM group vs control.

We found an increased risk of long-term subsequent MI, 30-day hospital readmissions, and 30-day incident HF among MI patients with AZM exposure compared to controls. Our findings are consistent with the 2012 Food and Drug Administration warning.