Coronary microvascular dysfunction and cardiovascular outcomes (Multicenter FLOW-CMD Registry): a prospective, multicentre cohort study in South Korea.

Abstract (English)

BACKGROUND: Coronary microvascular dysfunction often coexists with epicardial coronary artery disease. Data regarding its prevalence and prognosis in patients undergoing invasive coronary angiography are scarce. This study aimed to evaluate the prevalence and prognosis of coronary microvascular dysfunction in patients undergoing clinically indicated invasive coronary angiography in routine practice. METHODS: In this prospective, multicentre cohort study done in seven tertiary medical hospitals in South Korea, consecutive patients aged 18 years and older who were referred for clinically indicated invasive coronary angiography were systematically screened and evaluated by coronary physiological assessment. Obstructive epicardial coronary artery disease was defined as an intermediate stenosis (40-90% diameter stenosis), with fractional flow reserve of 0·80 or less or severe stenosis (>90% of diameter stenosis) treated with revascularisation without fractional flow reserve measurement. Coronary microvascular dysfunction was identified as coronary flow reserve below 2·0 and index of microcirculatory resistance of ≥25. The primary endpoint was a composite of all-cause death, myocardial infarction, clinically driven repeat revascularisation, or hospitalisation for heart failure. The Multicenter FLOW-CMD Registry study is registered with ClinicalTrials.gov (NCT05369182). FINDINGS: Between April 22, 2022, and Nov 19, 2024, 5764 patients were screened and 1003 patients were enrolled (756 men and 247 women). Among these patients, coronary microvascular dysfunction was observed in 123 (21·5%) of 573 patients with obstructive epicardial coronary artery disease and in 40 (9·3%) of 430 patients without obstructive epicardial coronary artery disease. At a median follow-up of 1·9 years, the primary endpoint occurred in 26 patients (2-year Kaplan-Meier estimate 18·8%) with coronary microvascular dysfunction and 70 patients (2-year Kaplan-Meier estimate 10·5%) with preserved microvascular function (hazard ratio 1·91 [95% CI 1·22-2·99]; p=0·0047). INTERPRETATION: In patients with suspected ischaemic heart disease undergoing invasive coronary angiography, coronary microvascular dysfunction coexisted with epicardial coronary artery disease and was associated with a higher risk of the composite of all-cause death, myocardial infarction, clinically driven repeat revascularisation, or hospitalisation for heart failure. FUNDING: Abbott Vascular and Boston Scientific.