Prognostic impact of secondary prevention medical therapy following myocardial infarction with non-obstructive coronary arteries: a Bayesian and frequentist meta-analysis

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a clinical entity with several causes and pathophysiologic mechanisms. Secondary prevention with medical therapy used in patients with obstructive coronary artery disease has unclear benefits in MINOCA patients. A literature search was conducted until 8 March 2022. Random-effect frequentist and hierarchical Bayesian meta-analyses were performed to assess the clinical impact of medical therapy [renin-angiotensin-aldosterone system (RAAS) inhibitors, statins, dual antiplatelet therapy (DAPT), β-blockers] in MINOCA patients. Outcomes of interest were all-cause mortality and major adverse cardiovascular events (MACE). A total of 12 663 MINOCA patients among five observational studies were analysed. The mean follow-up ranged from 12 to 90 months across studies. In frequentist meta-analysis, statins and β-blockers were associated with a lower risk of all-cause mortality [pooled adjusted hazard ratios (aHRs) 0.53 and 0.81, with 95% confidence intervals (CIs) (0.37-0.76) and (0.67-0.97), respectively]. Only RAAS inhibitors were associated with a lower risk of MACE [pooled aHR: 0.69, with 95% CI (0.53-0.90)]. Bayesian meta-analysis based on informative prior assumptions offered strong evidence only for the benefit of statins on decreasing the risk of all-cause death [Bayes factor (BF): 33.2] and moderate evidence for the benefit of RAAS inhibitors on decreasing the risk of MACE (BF: 9); assigning less informative prior distributions did not affect the results, yet it downgraded the level of evidence to anecdotal. In this meta-analysis, statins and RAAS inhibitors were consistently associated with a lower risk of all-cause mortality and MACE, respectively, in patients with MINOCA. Neutral prognostic evidence was demonstrated for β-blockers and DAPT.