Frequency and prognosis of type 2 myocardial infarction vs. non-ischemic myocardial injury: Large observational study from an emergency department.

Abstract

In current routine clinical practice of emergency unit, frequencies and characteristics of Type 2 Myocardial Infarction (T2MI), due to myocardial oxygen supply-demand mismatch in the absence of atherothrombosis and of non-ischemic myocardial injury (NIMI), i.e. troponin elevation without overt ischemia, remains to be investigated. Among medical records of all the patients admitted from January 2014 to December 2016 in a university hospital emergency unit ( n = 82,543), patients with elevated troponin Ic (≥ 0.10 μg/L) ( n = 4568) were adjudicated as T2MI if symptoms or signs of myocardial ischemia (typical chest pain and/or ECG changes), or as NIMI without such signs. Patients with missing admission biological data ( n = 112) or T1MI ( n = 2467) were excluded. Among the 1989 patients included, 539 (27%) were diagnosed as T2MI and 1450 (73%) as NIMI. When compared with NIMI, T2MI had higher troponin levels [0.27 (0.14–0.71) vs. 0.22 (0.13–0.54) μg/L, P = 0.008, respectively]. Risk factors were similar for both groups [age 84(74–90) vs. 84(75–91) y, P = 0.3], male sex (43 vs. 48%, P = 0.07), hypertension (67 vs. 71%, P = 0.133), diabetes (25 vs. 25%, P = 0.9), prior CAD (24 vs. 26%, P = 0.342), systemic inflammatory response syndrome (SIRS) (47 vs. 49%, P = 0.3), and systolic blood pressure (SBP) (130 (111–153) vs. 132 (112-153) mmHg, P = 0.545). Biological data on admission were also similar [hyperglycemia (glucose ≥ 11 mmol/L), 14 vs. 13%, P = 0.37, creatinine [96 (72–148) vs. 94 (72–141) μmole/L, P = 0.598], anemia (Hemoglobin ≤ 10 g/dL, 13 vs. 14%, P = 0.5), C-reactive protein elevation (CRP ≥ 3 mg/L, 88 vs. 89%, P = 0.7)]. Moreover, in-hospital mortality was high and similar for both groups (15 vs. 18%, P = 0.2), even when adjusted for confounding. This large real-life study shows that NIMI and T2MI are common and share the same risk factors, characterized by a high rate of infections and anaemia and a high risk of hospital mortality.