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 T2MI2012reclassified). 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 T2MI2012reclassified patients, respectively (all p < 0.01). Cardiovascular mortality at 90 days was 0% among T2MI2012reclassified, 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%) (T2MI2012reclassified vs. T2MI2007 and T1MI: p = 0.03 and 0.01, respectively).

CONCLUSIONS: T2MI2012reclassified has a substantially lower event-related mortality rate compared with T2MI2007 and T1MI. (Advantageous Predictors of Acute Coronary Syndromes Evaluation [APACE] Study; NCT00470587).