Background: 
Since the release of the “Fourth Universal Definition of Myocardial Infarction” consensus document and its classification for myocardial infarction (MI), distinguishing between the different subtypes, particularly between type 1 MI (T1MI) and type 2 MI, (T2MI) has been of great diagnostic and therapeutic importance. This study aimed to investigate whether copeptin, a stress hormone produced in the hypothalamus and surrogate marker for vasopressin helps to distinguish between T1MI and T2MI.

Methods: 
In a retrospective analysis, 1271 unselected consecutive patients presenting with symptoms suggestive of cardiac ischemia between 2011 and 2017 were evaluated. All patients underwent clinical assessment including cardiac troponin I and copeptin measurements. Patients diagnosed with ST-elevation MI were excluded. Afterwards patients were further classified into T1MI and T2MI using clinical assessment and coronary angiography.

Results: 
From all patients 1007 (86,7%) had no troponin elevation; whereas 153 (13,3%) patients had elevated troponin levels and were diagnosed as having an MI. From these, 78 (51%) were classified as T1MI and 76 (49%) as T2MI. The Mann-Whitney-U test revealed a significant difference in copeptin plasma concentration between patients with and without an MI (12,34 pmol/l vs 5,24 pmol/l, p<0,001), as well as between T1MI and T2MI patients (8,11 pmol/l vs 21,38 pmol/l, p=0,001). Despite this result, calculated AUC for using copeptin in differentiating between both MI types was 0,66 (CI: 0,57; 0,74) and showed a poor ability. A calculated logistic regression model including age, sex, systolic blood pressure, heart rate, eGFR and Troponin and Copeptin levels was significant (p<0,001).

Conclusion: 
This study showed that copeptin may have a fair ability in helping to differentiate T1MI from T2MI. Studies with larger patient cohorts are required to further confirm our findings.