Effect of Definition on Incidence and Prognosis of Type 2 Myocardial Infarction

Background: Uncertainties regarding the most appropriate definition and treatment of type 2 myocardial infarction (T2MI) due to supply-demand mismatch have contributed to inconsistent adoption in clinical practice.

Objectives: This study sought a better understanding of the effect of the definition of T2MI on its incidence, treatment, and event-related mortality, thereby addressing an important unmet clinical need.

Methods: The final diagnosis was adjudicated in patients presenting with symptoms suggestive of myocardial infarction by 2 independent cardiologists by 2 methods: 1 method required the presence of coronary artery disease, a common interpretation of the 2007 universal definition (T2MI₂₀₀₇); and 1 method did not require coronary artery disease, the 2012 universal definition (T2MI₂₀₁₂).

Results: Overall, 4,015 consecutive patients were adjudicated. The incidence of T2MI based on the T2MI₂₀₀₇ definition was 2.8% (n = 112). The application of the more liberal T2MI₂₀₁₂ definition resulted in an increase of T2MI incidence of 6% (n = 240), a relative increase of 114% (128 reclassified patients, defined as T2MI_{2012reclassified}). Among T2MI₂₀₀₇, 6.3% of patients received coronary revascularization, 22% dual-antiplatelet therapy, and 71% high-dose statin therapy versus 0.8%, 1.6%, and 31% among T2MI_{2012reclassified} patients, respectively (all p < 0.01). Cardiovascular mortality at 90 days was 0% among T2MI_{2012reclassified}, which was similar to patients with noncardiac causes of chest discomfort (0.2%), and lower than T2MI₂₀₀₇ (3.6%) and type 1 myocardial infarction (T1MI) (4.8%) (T2MI_{2012reclassified} vs. T2MI₂₀₀₇ and T1MI: p = 0.03 and 0.01, respectively).

Conclusions: T2MI_{2012reclassified} has a substantially lower event-related mortality rate compared with T2MI₂₀₀₇ and T1MI. (Advantageous Predictors of Acute Coronary Syndromes Evaluation [APACE] Study; NCT00470587).