Materials and Methods
The institutional review board ensured ethics approval in accordance with international recommendations. According to the decision of the Ethics Committee, (protocol number 2016-01884) patient consent was waived.
Patients were operated by two surgeons in 2016 and 2017. All major cardiac interventions, except surgery for terminal heart failure (assist devices, transplantation) or acute aortic disease (dissection), were included. Follow-up focused on 30 days after surgery and documented adverse events: Mortality, type 5 MI (which requires a significant hs-cTnT increase by analogy with ESC guidelines, although the threshold needs to be further defined), stroke, changes in ventricular function, and new ECG modifications.
Other parameters that could have an impact on enzyme elevation were also considered: Demographic and risk factors, i.e., preoperative MI, European System for Surgical Cardiac Risk Evaluation (EuroSCORE II), renal function, etc., direct surgery-related factors, i.e., type of cardioplegia, cross-clamp and cardiopulmonary bypass time, blood transfusions, intra-pericardial defibrillation, etc., and type of surgery.
Cardiac enzymes, i.e. hs-cTnT and creatine kinase myocardial band (CK-MB), were recorded before and 1, 6, 12, 24 to at least 48 hours after surgery. The hs-cTnT assay used (Elecsys Troponin T high sensitive by Roche, Basel, Switzerland) has the following specifications: 99th percentile URL is 14 nanogram per liter (ng/l) with a precision value (coefficient of variation ≤ 10%) of 13 ng/l, a limit of detection at 5ng/l and a blank at 3 ng/l [2]. CK-MB was measured in international units and its concentration expressed in units per liter (U/L).
Pre- and postoperative echocardiography was performed in all patients, with a focus on new ventricular dysfunction (considered significant if it had worsened by at least one grade according to the EuroSCORE classification) or new regional wall motion abnormalities attributable to coronary perfusion territories [3].