^{_{Seeking a New Threshold For High Sensetive Troponin I In Type 5 MI}}

Objective:

The diagnosis of post-CABG myocardial infarction is complicated, especially as regarding to high sensitive troponin (hs-cTnI)

The value suggested by the European Society of Cardiology in patients with normal preoperative value of Troponin is 10 times the 99^th percentile URL.

The study aimed to evaluate the normal postoperative hs-cTnI, and whether a raise in current hs-cTnI threshold value is indicated.

Methods:

374 patients were included in the study. Data collected included ECG, Echocardiography and cardiac catheterization prior to and post-operative, and hs-cTnI values within the first 48 hours post-op.

Results:

Out of the 151 (40.3%) patients admitted with normal pre-operative hs-cTnI, 148 (98%) presented with post-operative hs-cTnI values > 10 times the normal value. Mean hs-cTnI level at 6 hours post-operative was 9193 ng/l (min=11 ng/l, max=431802 ng/l). 11/154 (7.2%) patients were diagnosed with MI., according to Type 5 MI published criteria.

Out of the 223 (59.7%) patients with elevated pre-operative hs-cTnI, 167 (75%) had post-operative hs-cTnI values of 1.2 or more, and 10 times the normal values. Mean hs-cTnI level at 6 hours post-operative was 9949 ng/l (min=111 ng/l, max=174803 ng/l). 11/223 (4.9%) patients were diagnosed with MI., according to Type 5 MI criteria.

These findings suggest a sensitivity of 100% within the two groups, with very low specificity of 2.1 (ROC AUC=0.577) and 25.3 (ROC AUC=0.745) percent, between group of patients with normal pre-operative and those with high pre-operative hs-cTnI values, respectively.

Conclusion:

The majority of patients undergoing CABG reach hs-cTnI values significantly higher than currently stated values, suggesting post-operative MI.

In both groups, a significant increase in the threshold of hs-cTnI value (by 80 within normal pre-op hs-cTnI group, and by 2.7 in cases of initially elevated hs-cTnI values) for the diagnostic of Type 5 MI was indicated for major improvement of specificity, without affecting sensitivity.