Characteristics and Outcomes of MI with Non-obstructive Coronary Arteries in a South-east Asian Cohort

Background: MI with non-obstructive coronary arteries (MINOCA) is caused by a heterogenous group of conditions with clinically significant sequelae. Aim: This study aimed to compare the clinical characteristics and prognosis of MINOCA with MI with obstructive coronary artery disease (MICAD). Methods: Data on patients with a first presentation of MI between 2011 and 2014 were extracted from the Singapore Cardiac Longitudinal Outcomes Database and patients were classified as having either MINOCA or MICAD. The primary outcomes were all-cause mortality (ACM) and major adverse cardiac events (MACE), defined as a composite of ACM, recurrent MI, heart failure hospitalisation and stroke. Results: Of the 4,124 patients who were included in this study, 159 (3.9%) were diagnosed with MINOCA. They were more likely to be women, present with a non-ST-elevation MI, have a higher left ventricular ejection fraction and less likely to have diabetes, previous stroke or smoking history. Over a mean follow-up duration of 4.5 years, MINOCA patients had a lower incidence of ACM (10.1% versus 16.5%) and MACE (20.8% versus 35.5%) compared with MICAD. On multivariable analysis, patients with MINOCA had a lower risk of ACM (HR 0.42; 95% CI [0.21–0.82]) and MACE (HR 0.42; 95% CI [0.26–0.69]). Within the MINOCA group, older age, higher creatinine, a ST-elevation MI presentation, and the absence of antiplatelet use predicted ACM and MACE. Conclusion: While patients with MINOCA had better clinical outcomes compared with MICAD patients, MINOCA is not a benign entity, with one in five patients experiencing an adverse cardiovascular event in the long term.