Poor adherence to beta-blockers is associated with increased long-term mortality even beyond the first year after an acute coronary syndrome event.

Background: Acute coronary syndrome (ACS) patients are widely treated with long-term beta-blocker therapy after cardiac event. Especially for low-risk patients, the benefits of beta-blockers on survival and the optimal therapy duration remain unclear. We investigated the effect of adherence to beta-blockers on long-term survival of ACS patients. Methods and results: A total of 1855 consecutive ACS patients who underwent angiography and survived 30 days after were followed for a median of 8.6 years. During follow-up, 30.1% (n = 558) of patients died. Adherence was assessed as yearly periods covered by medication purchases and investigated as a dynamic time-dependent variable in Cox proportional hazards models. In a univariable model, non-adherence to beta-blockers was associated with higher all-cause mortality (Hazard ratio [HR] 2.99, 95% confidence interval [CI] 2.50-3.57; p < .001). Results were similar in multivariable models on both overall survival (HR 1.84, 95% CI 1.51-2.24; p < .001) and on 1-year landmark survival (HR 1.74, 95% CI 1.41-2.14; p < .001). In subgroup analyses, the increase in all-cause mortality was consistent among low-risk patients (HR 1.60, 95% CI 1.16-2.21; p = .004). Conclusion: Poor adherence to beta-blockers is associated with increased long-term mortality among ACS patients. Even low-risk patients seem to benefit from long-term beta-blocker therapy.Key messages Adherence to secondary prevention medications diminishes drastically over the years after an ACS event. Non-adherence to beta-blockers is associated with increased long-term mortality of ACS patients, and the effect on survival extends beyond the first year after an ACS event. Our follow-up was exceptionally lengthy with median follow-up period of 8.6 years.