Prevalence and factors influencing medication adherence after acute myocardial infarction: a systematic review and meta-analysis.

INTRODUCTION: Adherence to evidence-based secondary prevention medications is important for long-term management after acute myocardial infarction (AMI). Previous reviews have examined medication adherence and related factors but remain limited by heterogeneity in adherence measures and reliance primarily on narrative synthesis. AIM: We aimed to estimate the pooled prevalence of objectively measured medication adherence and identify associated factors after AMI. METHOD: Five databases (PubMed, Embase, Cochrane Library, Web of Science, and Ovid MEDLINE) were searched from January 1, 2000, to October 5, 2025. Observational studies using objective measures of medication adherence after AMI were included. Random-effects models were used to pool adherence prevalence estimates and adjusted odds ratios (ORs) for associated factors. Heterogeneity was explored through subgroup analyses by adherence measure, follow-up period, and geographical region. Robustness was assessed using leave-one-out sensitivity analyses. RESULTS: We included 18 retrospective cohort studies involving 680,966 participants from eight countries. The pooled prevalence of adherence was 64.9% (95% CI 56.1-73.8%) for statins, 58.9% (95% CI 49.3-68.4%) for beta‑blockers, 56.7% (95% CI 45.3-68.0%) for P2Y12 inhibitors, 61.3% (95% CI 50.8-71.9%) for angiotensin-converting enzyme inhibitor/angiotensin receptor blocker (ACEI/ARB), and 41.4% (95% CI 27.2-55.6%) for multiple-drug therapy (≥ 2 classes). Substantial heterogeneity remained within subgroups. Factors associated with higher adherence included hypertension (OR = 1.39, 95% CI 1.17-1.65), prior cardiovascular medication use (before the index admission for AMI; statins: OR = 1.33, 95% CI 1.15-1.54; beta-blockers: OR = 1.62, 95% CI 1.49-1.75; ACEI/ARB: OR = 1.77, 95% CI 1.65-1.89), ST-segment elevation myocardial infarction (OR = 1.23, 95% CI 1.02-1.48), percutaneous coronary intervention (OR = 2.16, 95% CI 1.34-3.46), and discharge from a cardiology ward (OR = 1.57, 95% CI 1.37-1.80). Factors associated with lower adherence included female sex (OR = 0.78, 95% CI 0.74-0.84), age ≥85 years (OR = 0.48, 95% CI 0.38-0.60), and chronic obstructive pulmonary disease (COPD; OR = 0.78, 95% CI 0.72-0.84). CONCLUSION: Medication adherence after AMI was suboptimal and associated with several factors. These findings may inform targeted monitoring and support but require further confirmation given substantial heterogeneity.