Short-Term Prognosis of Myocardial Injury, Type 1, and Type 2 Myocardial Infarction in the Emergency Unit

Type 2 myocardial infarction and nonischemic myocardial injury, corresponding to troponin elevation without atherothrombosis, are emerging concepts suspected of being common in emergency departments (ED). However, their respective frequencies, risk profiles, and short-term prognoses remain to be investigated.

Among all the patients admitted from January 2014 to December 2016 in a university hospital ED (n = 33,669), those with elevated conventional troponin Ic (≥0.10 µg/L) (n = 4436, 13%) were systematically adjudicated as having type 1 or type 2 myocardial infarction in the presence of symptoms or signs of myocardial ischemia (typical chest pain or electrocardiographic changes) or myocardial injury without such signs.

Among the 4436 patients included, 1453 (33%) were classified as having myocardial injury, 947 (21%) as having type 2 and 2036 (46%) as having type 1 myocardial infarction. Compared with type 1 patients, patients with type 2 myocardial infarction and myocardial injury were markedly older (respective median ages: 67, 81, and 84 years; P < .001) with more frequent comorbidities. In multivariate analysis, myocardial injury was associated with a lower risk of cardiovascular death (odds ratio 43; 95% confidence interval, 0.29-0.65; P < .001) but a higher risk of all-cause in-hospital death (odds ratio 1.43; 95% confidence interval, 1.02-2.00; P = .037). Systolic blood pressure <90 mm Hg and heart rate >100 beats per minute at admission were strongly associated with all-cause mortality, and the troponin rate was associated with cardiovascular mortality in all groups.

In a large study of patients with elevated troponins in an ED, myocardial injury and type 2 myocardial infarction were frequent and associated with a worse in-hospital prognosis than type 1 myocardial infarction resulting from noncardiovascular events.