Treatment and outcomes of type 2 myocardial infarction and myocardial injury compared with type 1 myocardial infarction.

BACKGROUND: Type 2 myocardial infarction (MI) is defined by a rise and fall of cardiac biomarkers and evidence of ischemia without unstable coronary artery disease (CAD) because of a mismatch in myocardial oxygen supply and demand. Myocardial injury is similar but does not fulfill the clinical criteria for MI. There is uncertainty in terms of the clinical characteristics, management, and outcomes of type 2 MI and myocardial injury in comparison with type 1 MI.

PATIENTS AND METHODS: Patients admitted to a Veterans Affairs tertiary care hospital with a rise and fall in cardiac troponin were identified. MI and injury subtypes, presentation, management, and outcomes were determined.

RESULTS: Type 1 MI, type 2 MI, and myocardial injury occurred in 137, 146, and 175 patients, respectively. Patients with type 2 MI were older (P=0.02), had lower peak cardiac troponin (P<0.001), and were less likely to receive aspirin and statin at discharge (P<0.001) than type 1 MI survivors. All-cause mortality (median follow-up: 1.8 years) was not different between patient groups (type 1 MI mortality: 29.9%, type 2 MI: 30.8%, myocardial injury: 29.7%; log rank P=0.94). A significant proportion of deaths were attributed to cardiovascular causes in all subgroups (type 1 MI: 34.1%, type 2 MI: 17.8%, myocardial injury: 30.8%).

CONCLUSION: Patients with type 2 MI and myocardial injury were less likely to receive medical therapy for CAD than those with type 1 MI. No differences in all-cause mortality among MI subtypes were observed. Additional studies to determine optimal medical therapy and risk stratification strategies for these high-risk populations are warranted.