Using the SWEDEHEART registry, 97,575 patients with a first-time MI who were discharged on beta-blockers between 2006 and 2015 were studied. Around one-third (33,126) of patients were discharged on ≥50% of the target beta-blocker dose used in previous randomised trials, while two-thirds (66.1%) received <50% of the target dose.
The investigators found that the primary composite endpoint of all-cause death or reinfarction within 1 year of discharge was similar for patients treated with ≥50% of the target beta-blocker dose compared with patients receiving <50% of the target dose (hazard ratio [HR] 1.03; 95% confidence interval [CI] 0.99–1.08). In fact, risk was higher with patients on ≥50% vs. <50% target beta-blocker dose when stroke, atrial fibrillation or heart failure hospitalisation were added to the composite endpoint (HR 1.08; 95% CI 1.04–1.12).
When patients were followed for 5 years, similar results were obtained, with no apparent difference in cardiovascular outcomes with lower beta-blocker doses. The results were also consistent across the subgroups studied, including patients who developed heart failure post-MI.
These interesting findings suggest that it is now time to further investigate the use of beta-blockers after MI and that new trials are needed.