Pathological findings at invasive assessment in MINOCA: a systematic review and meta-analysis

BACKGROUND: Pathological mechanisms of myocardial infarction with non-obstructive coronary arteries (MINOCA) are heterogeneous, with an unknown impact on prognosis, and often remain unrecognised in clinical practice. This study aimed to evaluate the prevalence and prognostic impact of pathological findings by invasive coronary angiography (ICA), optical coherence tomography (OCT), and coronary function testing in MINOCA. METHODS: Studies published until August 2023 were searched on PubMed and SCOPUS and included if reporting the prevalence of patients with non-obstructive coronary arteries (NObs-CA; 1-49% coronary stenosis) versus normal coronary arteries (NCA; 0% coronary stenosis) by ICA, pathological findings by OCT, and/or coronary vasomotor tests in MINOCA. Newcastle-Ottawa Scale was used for quality assessment. The pooled prevalence of pathological findings was estimated with random-effects models. Pooled risk ratios (RRs) with 95% CIs of all-cause death, MI and the composite of both in patients with NObs-CA versus NCA were calculated at short-term (<1 month), 1-year and long-term follow-up (> 1 year). RESULTS: Forty-five studies including 17 539 patients were analysed. The pooled prevalence of NObs-CA at ICA was 53% (95% CI 0.47 to 0.60). OCT showed acute pathological findings in 62% (95% CI 0.44 to 0.78) of patients and coronary vasomotor tests were positive in 49% (95% CI 0.31 to 0.67). NObs-CA compared with NCA was associated with an increased 1-year risk of all-cause death or MI (RR=1.49 (95% CI 1.17 to 1.90)) and MI alone (RR=1.80 (95% CI 1.26 to 2.59)), whereas the risk of all-cause death was comparable. Similar results were seen at long-term, but not at short-term follow-up. CONCLUSIONS: Stratification of MINOCA into NObs-CA versus NCA has prognostic value. OCT and vasospasm testing, often informative about the pathological mechanism of MINOCA, should be part of an invasive diagnostic algorithm. PROSPERO REGISTRATION NUMBER: CRD42023468183.