Cardiovascular Mortality After Type 1 and Type 2 Myocardial Infarction in Young Adults

Background: Type 2 myocardial infarction (MI) and myocardial injury are associated with increased short-term mortality. However, data regarding long-term mortality are lacking. Objectives: This study compared long-term mortality among young adults with type 1 MI, type 2 MI, or myocardial injury. Methods: Adults age 50 years or younger who presented with troponin >99th percentile or the International Classification of Diseases code for MI over a 17-year period were identified. All cases were adjudicated as type 1 MI, type 2 MI, or myocardial injury based on the Fourth Universal Definition of MI. Cox proportional hazards models were constructed for survival free from all-cause and cardiovascular death. Results: The cohort consisted of 3,829 patients (median age 44 years; 30% women); 55% had type 1 MI, 32% had type 2 MI, and 13% had myocardial injury. Over a median follow-up of 10.2 years, mortality was highest for myocardial injury (45.6%), followed by type 2 MI (34.2%) and type 1 MI (12%) (p < 0.001). In an adjusted model, type 2 MI was associated with higher all-cause (hazard ratio: 1.8; 95% confidence interval: 1.2 to 2.7; p = 0.004) and cardiovascular mortality (hazard ratio: 2.7; 95% confidence interval: 1.4 to 5.1; p = 0.003) compared with type 1 MI. Those with type 2 MI or myocardial injury were younger and had fewer cardiovascular risk factors but had more noncardiovascular comorbidities. They were significantly less likely to be prescribed cardiovascular medications at discharge. Conclusions: Young patients who experience a type 2 MI have higher long-term all-cause and cardiovascular mortality than those who experience type 1 MI, with nearly one-half of patients with myocardial injury and more than one-third of patients with type 2 MI dying within 10 years. These findings emphasize the need to provide more aggressive secondary prevention for patients who experience type 2 MI and myocardial injury.