Abstract and Introduction
Aims The differentiation of type 1 and type 2 myocardial infarction (T1MI, T2MI) is important, but challenging in the emergency department. We aimed to investigate the clinical characteristics and cardiovascular outcome of T2MI patients and to develop a clinical decision tool to differentiate T1MI and T2MI patients.
Methods and results We prospectively enrolled 1548 patients with suspected MI. All patients were followed for up to 2 years to assess mortality. We used logistic regression with backward step-down selection to determine the most important predictors of T2MI. Based on these regression coefficients, we developed a diagnostic prediction model (score) to diagnose T2MI. T2MI was the final diagnosis of 99 patients. Patients with T2MI showed a high 1-year mortality rate (13.8%), which equals that of T1MI patients (9.4%). Female sex (Beta 1.27 [95% confidence interval; CI 0.67–1.90]), not having radiating chest pain (Beta 1.62 [CI 0.96–2.34]) and a baseline high-sensitivity troponin I concentration ≤ 40.8 ng/L (Beta 1.30 [CI 0.74–1.89]) were the strongest predictors for T2MI. Their combination resulted in an area under the curve of 0.71 to discriminate T1MI and T2MI. The binary score based on this model assigns one point to each of the predictors. Patients with the highest score value of 3 had a 72% probability of T2MI.
Conclusion T2MI patients are a heterogeneous population with high-cardiovascular risk. A score based on laboratory and clinical parameters might help to differentiate T1MI and T2MI patients. The additional use of this score in clinical routine needs to be investigated prospectively.
Patients with suspected acute myocardial infarction (MI) account for approximately 10% of all emergency department (ED) patients.[1,2] Those patients with MI are at high risk and require further diagnostic evaluation or invasive treatment. According to the current universal definition type 1 and type 2 MI (T1MI, T2MI) are differentiated based on the pathophysiological background. T1MI is defined by an acute coronary plaque disruption, while T2MI is defined by an imbalance of myocardial oxygen supply and demand. Those patients with T1MI usually require an urgent invasive approach to improve outcome. Patients with T2MI on the other hand reflect a heterogeneous population with various other causes of symptoms, and an early invasive approach might not only be not warranted, but even harmful in those patients. Therefore, differentiation of both MI types represents a clear clinical need.
The causes of T2MI include e.g. arrhythmias, cardiogenic shock, coronary spasm, and other causal factors. The prevalence of T2MI has been reported between 2 and 30% of all MI patients. As elevated troponin concentrations are essential for the diagnosis of T1MI as well as T2MI, it is not surprising that troponin measured by medium-sensitivity assays was not able to differentiate between both types. Nevertheless, the clinical characteristics differ as T2MI patients tend to be older, are more often females and have different symptoms compared to T1MI patients.[7–9] Furthermore, earlier studies reported a poor outcome of T2MI patients with mortality rates of up to 50% after 4 years.[9–12] The large Swedeheart register identified coronary artery disease (CAD) as an important determinant for T2MI since these were at highest risk for death and had more often cardiovascular comorbidities. Again, this highlights that differentiation of these two subtypes of MI is clinically important, but remains a challenging task for ED physicians or the consulting cardiologists.
Therefore, in the present article, we aim to investigate the clinical characteristics and the cardiovascular outcome of patients with T2MI in a large prospective cohort of patients with suspected MI. Furthermore, we aim to differentiate patients with T2 from T1MI patients based on available clinical findings in order to improve decision making for ED physicians.
Eur Heart J. 2017;38(47):3514-3520. © 2017 Oxford University Press
Copyright 2007 European Society of Cardiology. Published by Oxford University Press. All rights reserved.