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

Abstract

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.

Keywords: myocardial injury; outcomes; troponin; type 2 myocardial infarction; young adults.

FIGURE 1. Kaplan-Meier Curves

Kaplan-Meier failure curves for (A) all-cause and (B) cardiovascular death for type 1 myocardial infarction (MI), type 2 MI, and myocardial injury. All-cause mortality was significantly higher for type 2 MI and myocardial injury compared with type 1 MI, whereas cardiovascular mortality was significantly higher for type 2 MI. CV = cardiovascular; HR = hazard ratio.

FIGURE 2. Distribution of Various Etiologies of Type 2 MI and Myocardial Injury

A broad variety of underlying etiologies that result in demand/supply mismatch in (A) type 2 MI and (B) myocardial injury. The colors represent the various etiologies and remain the same across the 2 panels. Abbreviations as in Figure 1.

FIGURE 3. All-Cause and Cardiovascular Mortality by Etiology of Type 2 MI or Myocardial Injury

The bar chart illustrates all-cause (blue) and cardiovascular mortality (red) among the most common etiologies of type 2 MI or myocardial injury, in descending order of all-cause mortality. This figure illustrates the wide spectrum of mortality and highlights the different associations between all-cause and cardiovascular mortality. Abbreviations as in Figure 1.

CENTRAL ILLUSTRATION. Clinical Features and Outcomes of Young Adults With First-Time Type 1 Myocardial Infarction, Type 2 Myocardial Infarction, or Myocardial Injury

The pie chart shows the distribution of the 3 groups. The table illustrates key differences in baseline characteristics. The horizontal bar graph displays in-hospital mortality of the 3 groups. Vertical bar graphs display annualized incidence rates of noncardiovascular and cardiovascular mortality, the sum of which (total height of bar) depicts all-cause mortality. Type 2 myocardial infarction (MI) and myocardial injury had high in-hospital mortality, as well as long-term noncardiovascular and cardiovascular mortality.