Clinical Presentation and In-Hospital Outcomes of Acute Myocardial Infarction in Young Patients: Japanese Nationwide Registry.

Background: Acute myocardial infarction (AMI) in young patients is a concerning issue because of its adverse health and social impacts. Nevertheless, risk factors and prognosis of AMI in young patients are yet to be characterized. Objectives: This study aimed to characterize AMI in young patients who underwent primary percutaneous coronary intervention (PCI) using large-scale nationwide all-comer registry data in Japan, the Japanese Percutaneous Coronary Intervention (J-PCI). Methods: This retrospective cohort study evaluated the J-PCI registry data of patients with AMI aged 20 to 79 years who underwent primary PCI between January 2014 and December 2018. Data on risk factor profiles, clinical features, post-procedural complications, and in-hospital outcomes were reviewed. Results: Among 213,297 patients with AMI who underwent primary PCI, 23,985 (11.2%) were young (ages 20 to 49 years). Compared with the older group (ages 50 to 79 years; n = 189,312), the younger group included a higher number of men, smokers, patients with dyslipidemia, and patients with single-vessel disease, and a lower number of patients with hypertension and diabetes. Despite favorable clinical profiles, younger age was associated with a higher rate of presentation with cardiopulmonary arrest (CPA). Further, concomitant CPA was strongly associated with in-hospital mortality in young patients (odds ratio: 14.2; 95% CI: 9.2 - 21.9). Conclusions: Younger patients with AMI presented a higher risk of CPA, which was strongly associated with in-hospital mortality. The results of this study highlight the importance of primary AMI prevention strategies in young individuals.