Prevalence and prognostic relevance of non-obstructive coronary atherosclerosis in MINOCA: a meta-analysis of 35 studies

Abstract Background Myocardial infarction with non-obstructive coronary arteries (MINOCA) can result from a variety of pathological mechanisms, not always associated with atherosclerosis. It has been suggested to distinguish between patients without obstructive coronary artery disease (NObs-CAD, stenosis diameter 1-49%), and patients with smooth coronary arteries (NCA), but differences in terms of prognosis or therapeutic approaches have not been clearly elucidated. Objectives The aim of this study is to evaluate the prevalence and prognostic impact of NObs-CAD as assessed by invasive coronary angiography (ICA) in MINOCA. Methods A meta-analysis was performed including studies reporting the prevalence of NObs-CAD versus NCA in MINOCA patients. Data on prognosis stratified by the presence of NObs-CAD were collected. Random-effects models were used to estimate the prevalence of NObs-CAD. Pooled risk ratios (RR) with 95% confidence intervals (CI) for all-cause death, myocardial infarction (MI), and the composite of both outcomes of patients with NObs-CAD compared to NCA were calculated at short-term (<1 month), 1-year and long-term follow-up (more than 1 year). Results Thirty-five studies were analysed. The pooled prevalence of NObs-CAD estimated by ICA was 53% [95% CI 47-60%]. Heterogeneity was high (I2=98.0%), but none of the clinical and instrumental characteristics tested in meta-regression analyses had a significant impact on the I2, except for age (residual I2=97.2%, p=0.014) and geographical context. Specifically, studies conducted outside Europe reported a higher prevalence of NObs-CAD with lower I2 values. Thirteen studies provided prognostic data. The presence of NObs-CAD was associated with an increased risk of death or MI compared to NCA, as well as the risk of MI at 1-year follow-up (RR = 1.49 [95% CI 1.17-1.90] and RR = 1.80 [95% CI 1.26-2.59], respectively), whereas the risk of death was comparable. Similar results were observed at long-term, but not at short-term follow-up. Out of 13 studies, 4 provided information regarded the medications at discharge stratified by the presence or absence of NObs-CAD. NObs-CAD patients received more often aspirin (89% vs 69%; p<0.01), P2Y12-inhibitors (52% vs 29%; p<0.01), angiotensin-converting enzyme inhibitors/angiotensin-receptor blockers (53% vs 40%; p<0.01), beta-blockers (70% vs 57%; p<0.01), and statins (86% vs 60%; p<0.01) compared to NCA. Conclusions Stratification of patients according to the degree of coronary stenosis has prognostic implications in the setting of MINOCA, since NObs-CAD patients present a higher risk of reinfarction. Further dedicated trials are needed to clarify whether these patients may benefit from a tailored approach in terms of secondary prevention strategies.Central illustration