Clinical Characteristics and Outcome of Patients With Myocardial Infarction With Nonobstructive Coronary Arteries in Japan: Insights From the Miyagi Acute Myocardial Infarction Registry Study

Background Clinical characteristics and outcomes of patients with myocardial infarction (MI) with nonobstructive coronary arteries (MINOCA) are not fully understood, particularly in Japan. Methods and Results We enrolled a total of 8881 patients with acute MI from the Miyagi Acute Myocardial Infarction Registry Study (2012–2020), with a median age of 69 years. Among them, 239 patients (2.7%) were diagnosed with MINOCA. Compared with those with MI with obstructive coronary artery disease (MI‐CAD), patients with MINOCA were more often women, had a higher incidence of non–ST‐segment–elevation MI and a lower prevalence of dyslipidemia. Compared with patients with MI‐CAD, patients with MINOCA in all age groups (<59, 60–69, 70–79, >80 years of age) had a higher incidence of non–ST‐segment–elevation MI. Additionally, those ≤59 years of age were more often women and had a lower prevalence of diabetes and dyslipidemia. In‐hospital mortality increased with age in patients with MI‐CAD (3.9% for <59 years of age, 5.6% for 60–69 years of age, 8.3% for 70–79 years of age, and 15.2% for >80 years of age; P <0.01), but not in patients with MINOCA (4.5%, 7.4%, 6.0%, and 9.6%, respectively; P =0.36). Compared with patients with MI‐CAD, patients with MINOCA had lower in‐hospital mortality for Killip class IV (40.7% versus 20.0%; adjusted odds ratio [OR], 0.31 [95% CI, 0.10–0.94]; P =0.04) and renal dysfunction (20.0% versus 7.1%; adjusted OR, 0.29 [95% CI, 0.09–0.96]; P =0.04). Conclusions Patients with MINOCA exhibit distinct clinical characteristics and outcomes compared with those with MI‐CAD, particularly in terms of age, sex, prevalence of comorbidities, and in‐hospital mortality. These findings underscore the importance of tailored clinical approaches for patients with MINOCA.