Perioperative myocardial cell injury: the role of troponins

Early recognition of minor myocardial cell injury and appropriate treatment may prevent development of myocardial infarction as one of the most severe postoperative cardiac complications. Troponins have been shown to be sensitive biochemical markers for the assessment of myocardial cell injury. We investigated prospectively 67 cardiac risk patients undergoing elective non-cardiac surgery. Troponin T (TNT) concentrations were measured during the perioperative period, and in those patients with increased TNT (cut-off 0.2 ng ml-1), troponin I (TNI) concentrations were measured additionally (cut-off 0.6 ng ml-1). Patients were allocated to one of three groups: group I, all patients with normal TNT concentrations had a good cardiac outcome (80.5%). In those patients with increased TNT concentrations (19.5%) TNI was also positive; group II, patients (8.8%) with only slightly increased TNT concentrations (0.32-0.99 ng ml-1) also had a good outcome, indicating minor myocardial cell injury, whereas patients with cardiac complications (11.9%) had higher TNT concentrations (0.47-9.8 ng ml-1) (P < 0.05) (group III). With a TNT cut-off at 0.2 ng ml-1, the positive predictive value for adverse outcome was 61.5%; the negative predictive value was 100%. With a TNT cut-off at 0.6 ng ml-1, the positive predictive value for adverse outcome increased to 87.5%, but the negative predictive value was still high (98%). Most of the patients showed an increase in TNT content from the day of surgery until the third postoperative day. We conclude that serial troponin measurements during the perioperative period identify pre-, intra- and postoperative myocardial cell injury. The concentration of troponin T may reflect the degree of injury and help categorize the subsequent risk.