Type 2 myocardial infarction in clinical practice

Abstract

Objective: We aimed to assess differences in incidence, clinical features, current treatment strategies and outcome in patients with type 2 vs. type 1 acute myocardial infarction (AMI). Methods and results: All 20 138 hospitalisations in Sweden with a diagnosis of AMI registered during 2011 in the Swedish Web-system for Enhancement and Development of Evidence-based care in Heart disease Evaluated According to Recommended Therapies were classified into types 1-5 in accordance with the universal definition of myocardial infarction (MI) from 2007. Type 1 AMI was present in 88.5% of the cases while 7.1% were classified as type 2 AMI. Higher age, female sex, comorbidities, impaired renal function, anaemia and smaller extent of myocardial necrosis characterised patients with type 2 AMI. While normal coronary arteries were more frequently seen (42.4% vs. 7.4%), an invasive treatment was less common, and antiplatelet medications were less prescribed in patients with type 2 AMI compared with type 1 AMI. The group with type 2 AMI had significantly higher crude 1-year mortality compared with the group with type 1 AMI (24.7% vs. 13.5%, p<0.001). However, after adjustment, the HR for 1-year mortality in patients with type 2 AMI was 1.03 (95% CI 0.86 to 1.23). Conclusions: In this real-life study, 7.1% of myocardial infarctions were classified as type 2 AMI. These patients were older, predominantly women and had more comorbidities. Invasive treatment strategies and cardioprotective medications were less used. Patients with type 2 AMI had higher crude mortality compared with type 1 patients with MI. However, after adjustment, the 1-year mortality was similar.