Nationwide Analysis of Spontaneous Coronary Artery Dissection-Related Acute Myocardial Infarction in Japanese Patients Aged ≤60 Years Using the Administrative JROAD-DPC Database.

Background: Spontaneous coronary artery dissection (SCAD) causes acute myocardial infarction (AMI). Clinical characteristics of SCAD patients remain insufficiently understood. Methods and Results: We analyzed AMI patients aged ≤60 years using the nationwide Japanese Registry of All Cardiac and Vascular Diseases-Diagnosis Procedure Combination database (2012.04.01-2022.03.31). SCAD was defined by International Classification of Diseases, 10th revision code I24.8 and the presence of keyword 'coronary artery dissection'. The primary outcome was in-hospital all-cause mortality. Among 96,304 eligible patients, 330 (0.34%) had SCAD. SCAD patients were younger (P<0.001), more often female (P<0.001), and had fewer atherogenic risk factors. They less frequently received aspirin (P<0.001), angiotensin-converting enzyme inhibitor/angiotensin II receptor blocker (P<0.001), statins (P<0.001), and percutaneous coronary intervention (PCI; P<0.001). After propensity score matching, in-hospital all-cause mortality did not differ between SCAD and non-SCAD patients (1.0% vs. 2.9%; P=0.142). The subgroup analysis revealed that the use of aspirin was associated with a lower adjusted in-hospital all-cause mortality (P=0.002), whereas primary PCI (P=0.223), β-blocker (P=0.646), and statin (P=0.608) were not. Of note, older SCAD patients were more likely to exhibit inferior MI (P=0.036 for trend) with shorter duration of hospitalization (P=0.025 for trend). Conclusions: Short-term outcomes in SCAD patients are comparable with those of atherosclerotic AMI. While aspirin lowered in-hospital mortality, PCI, β-blocker, and statin did not. Our findings suggest the need for physicians to select appropriate therapeutic management in SCAD patients to achieve better outcomes.