Troponin I as expression of myocardial damage after major vascular surgery

Introduction and methods

In the perioperative period different levels of Troponin I (TnI) increase allow the identification of different severity degrees of myocardial damage [1]. Aim of the present study was to verify the correlation of TnI increase with clinical, ECG and Echo TT data and with the stratification of risk in patients submitted to major vascular surgery. A prospective observational study was performed on 51 patients submitted to major vascular surgery and then admitted to ICU. Preoperative measurements of TnI, CK-MB isoform, ECG and Echo TT were obtained. Then blood samples for TnI and CK-MB were obtained every 6 hours for 72 hours after surgery and then once daily. Twelve-leads ECG was registered daily. A new echocardiogram was obtained 48-72 hours after surgery. According to our laboratory and to NACB [2], two cut-off values for TnI were used as follows: normal values = <0.11 ng/ml; >0.11 to <1.5 ng/ml; >1.5 ng/ml. Patients were then subdivided into three groups in relation to TnI levels: Group T0 = normal values (<0.11 ng/ml); Group T1 = >0.11 to <1.5 ng/ml; Group T2 = >1.5 ng/ml. In every group TnI values were related to CK-MB, ECG and echo TT results. Patients were reassessed 3 months after surgery by means of telephone survey, ECG, echo TT and clinical evaluation.

Results and discussion

In the T0 group TnI and CK-MB levels were normal, as ECG traces and echocardiography. In the T1 group TnI levels were higher than the first cutoff value, although CK-MB levels were normal as ECG and echocardiography. Finally, in four out of eight patients of the T2 group, with TnI >6 ng/ml and CK-MB values >3.6 ng/ml, an acute myocardial infarction was diagnosed. Two of these patients died. The 3 months follow-up did not detect any cardiac adverse events in survivors. Our results demonstrate a high incidence of TnI increase in the perioperative period after major vascular surgery. In the vast majority of cases serum TnI increase is limited. In our opinion a mild increase of TnI individuates a group of patients at low risk of cardiac adverse events. In the acute phase these patients with minimal myocardial cellular damage do not need any invasive diagnostic or therapeutic procedure nor any aggressive pharmacological treatment. Nevertheless, it is mandatory to re-evaluate this issue in a greater number of patients in order to establish a new and more reliable cutoff value of TnI in the perioperative setting of major vascular surgery.