Predictors of mortality in myocardial infarction and nonobstructed coronary arteries. a systematic review and meta-regression

BACKGROUND: The long-term mortality of patients with myocardial infarction and non-obstructed coronary arteries (MINOCA) remains poorly defined. This study aimed to determine long-term mortality of patients with MINOCA and identify potential prognostic determinants of long-term outcome. METHODS: We searched Pubmed, Embase and Cochrane databases and reviewed cited references up to December 31, 2018 to identify studies with > 6 months follow-up data. RESULTS: We selected 44 studies including 36,932 patients (20,052 women and 16,880 men). During a median follow-up of 25 months (interquartile range: 23-39 months), 1,409 patients had died (3.8%). Overall, annual mortality rate was 2.0% (95% CI: 1.5% to 2.4%) with significant heterogeneity (I2=80%, P<0.001). Meta-analysis of the 26 studies comparing patients with MINOCA with those with myocardial infarction and obstructive coronary artery disease showed that annual rates of long-term total mortality were 2.2% (95% CI: 1.7-2.7%) and 5.0% (95% CI: 4.1-5,9%) respectively, with a significant difference between the two groups (Relative Risk: 0.60, 95% CI: 0.46-0.78, p<0.001). Meta-regression analysis demonstrated that normal ejection fraction (p=<0.0001) and normal coronary arteries at angiography (p=0.004) were inversely related to long-term mortality whilst use of beta-blockers during follow-up (p=0.010) and ST depression on the admission electrocardiogram (p=0.016) were directly related with worse outcome. CONCLUSIONS: The long-term mortality after MINOCA is lower than that in patients with myocardial infarction and obstructive coronary artery disease, but it is not trivial. Reduced ejection fraction, non-obstructive coronary artery disease, use of beta-blockers during follow up and ST depression on the admission electrocardiogram are significant predictors of long-term prognosis. (PROSPERO registration number CRD42019117042).