Endothelial dysfunction and long-term outcomes in patients with myocardial infarction and non-obstructive coronary arteries

BACKGROUND: There is little information regarding the characteristics of patients with myocardial infarction with non-obstructive coronary arteries (MINOCA) in terms of coronary endothelial function and prognosis, as compared to patients with angina and non-obstructive coronaries (ANOCA). We assessed differences in clinical profile, endothelial function and prognosis between patients undergoing acetylcholine (ACH) testing for MINOCA or ANOCA. METHODS: We combined two cohorts of patients undergoing ACH testing - ENDOCOR (multicentre; 2015-2023) and FISIOTON (single-centre; 2018-2024) - totalling 723 patients. Endothelial dysfunction was defined as any epicardial vasoconstriction to ACH or endothelium-dependent coronary flow reserve ≤1.5. RESULTS: MINOCA was diagnosed in 68 (9.4%) patients. Endothelial dysfunction was found in 57.4%, epicardial spasm in 7.05% and microvascular spasm in 1.94%, without differences between MINOCA and ANOCA. In multivariable regression, MINOCA was independently associated with resting chest pain (OR 3.63, 95% CI: 1.84-7.66), previous MI (OR 2.91, 95% CI: 1.29-6.30) and active smoking (OR 2.15, 95% CI: 1.04-4.30). Over a median follow-up of 3.0 years, major adverse cardiovascular events (MACE) occurred in 7.5% of patients. MINOCA (HR 2.81, 95% CI: 1.40-5.67, p = 0.004), endothelial dysfunction (HR 2.59, 95% CI: 1.29-5.21, p = 0.008) and male sex (HR 2.01, 95% CI: 1.13-3.58, p = 0.017) were independently associated with MACE. Patients with MINOCA and endothelial dysfunction had the highest event rate (19.4%). CONCLUSIONS: In patients with non-obstructive coronary arteries undergoing ACH testing, endothelial dysfunction and a MINOCA presentation were independently associated with adverse events, whereas classical spasm endotypes were not.