Identification of and therapeutic approaches to standard modifiable risk factors (SMuRFs), including hypertension, diabetes, dyslipidemia, and smoking, have led to improved survival of patients at risk for coronary events. However, recent studies have indicated that a significant proportion of patients with acute myocardial infarction (AMI) have no SMuRFs. We aimed to assess in-hospital outcomes and the prevalence of these patients using the Japanese nationwide percutaneous coronary intervention (J-PCI) registry.

The J-PCI is a procedure-based registration program in Japan. A total of 115,437 PCI procedures were performed on patients with AMI between January 2019 and December 2020. The participants were divided into 2 groups: those with at least 1 SMuRF and those without any SMuRFs. The primary outcome was in-hospital mortality.

Of the 115,437 patients with AMI, 1,777 (1.6%) had no SMuRFs. Patients without SMuRFs were older; more likely to have left main disease; and more likely to present with heart failure, cardiogenic shock, and cardiac arrest than those with SMuRFs, resulting in higher rates of mechanical circulatory support use and impaired post-PCI coronary blood flow. In-hospital mortality was significantly higher in patients without SMuRFs than in those with SMuRFs (18.3% vs 5.3%, P < .001), irrespective of the presence or absence of ST-segment elevation.

In Japan, where annual health checks are mandated under universal health care coverage, the vast majority of patients with AMI undergoing PCI have SMuRFs. However, although small in number, patients without SMuRFs are more likely to present with life-threatening conditions and have worse in-hospital survival.