Type 1 or Type 2 Myocardial Infarction in Patients with a History of Coronary Artery Disease: Data from the Emergency Department

Abstract

A type 2 myocardial infarction (T2MI) is the result of an imbalance between oxygen supply and demand, without acute atherothrombosis. T2MI is frequent in emergency departments (ED), but has not been extensively evaluated in patients with previously known coronary artery disease (CAD). Our study assessed the incidence and characteristics of T2MI compared to type 1 (T1MI) in CAD patients admitted to an ED. Among 33,669 consecutive patients admitted to the ED, 2830 patients with T1MI or T2MI were systematically included after prospective adjudication by the attending clinician according to the universal definition. Among them, 619 (22%) patients had a history of CAD. Using multivariable analysis, CAD history was found to be an independent predictive factor of T2MI versus T1MI (odds ratio (95% confidence interval) = 1.38 (1.08–1.77), p = 0.01). Among CAD patients, those with T2MI (n = 254) were older (median age: 82 vs. 72 years, p < 0.001), and had more frequent comorbidities and more frequent three-vessel disease at the coronary angiography (56% vs. 43%, p = 0.015). Percutaneous coronary intervention was by far less frequent after T2MI than after T1MI (28% vs. 67%, p < 0.001), and in-hospital mortality was twice as high in T2MI (15% vs. 7% for T1MI, p < 0.001). Among biomarkers, the C reactive protein (CRP)/troponin Ic ratio predicted T2MI remarkably well (C-statistic (95% confidence interval) = 0.84 (0.81–0.87, p < 0.001). In a large unselected cohort of MI patients in the ED, a quarter of patients had previous CAD, which was associated with a 40% higher risk of T2MI. CRP/troponin ratios could be used to help distinguish T2MI from T1MI.