Prognostic value of troponin I after coronary artery bypass grafting (AMIRI-CABG study)

In 2017, the European Society of Cardiology outlined the importance of the problem of diagnosing myocardial ischemia-reperfusion injury following coronary artery bypass grafting. Myocardial injury can be accompanied by a critical decline in the cardiac index and an increase in cardiac troponin I plasma levels. The prognostic value troponin I elevation after coronary artery bypass grafting is poorly understood. Objective: to determine the prognostic value of troponin I plasma levels in relation to a fall in the cardiac index after coronary artery bypass grafting (CABG). Task: To determine the probability the cardiac index falling below 2.2 for troponin I levels in the first hours, and on days 1, 2, 3, 4 after CABG. Materials and methods. The single-center, non-randomized prospective study, running from 2016 to 2019, included 336 patients admitted for elective surgical treatment of coronary artery disease. The CABG patients were divided into three observation groups: off-pump (n = 175), on-pump (n = 128), and pump-assisted (n = 33). Troponin I levels were measured in the first hours, and on days 1, 2, 3, 4 after surgery using the Pathfast Compact immunoassay analyzer. Cardiac index was measured by invasive method. Results. In patients with a cardiac index higher than 2.2, troponin I level did not exceed 0.5 ng/mL in the off-pump group, 6 ng/mL in the on-pump group, and 3.5 ng/mL in the pump-assisted group. Patients with cardiac index lower than 2.2 have comparable troponin I levels in all groups - 21 ng/mL. Troponin I thresholds on day 1 after surgery, which, when exceeded, was associated with the likelihood of the cardiac index falling below 2.2, was 3.78 ng/mL in the off-pump group, 9.67 ng/mL in the on-pump group and 17.06 ng/mL in the pump-assisted group. Conclusion. After off-pump CABG, clinically significant myocardial injury should be expected at lower troponin I levels (3.78 ng/mL) than after on-pump CABG (9.67 ng/mL) and pump-assisted CABG (14.7 ng/mL).