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One hundred and sixteen consecutive patients undergoing open heart surgery were studied to evaluate the diagnostic use of cardiac specific troponin T in serum (S-TnT) measured preoperatively, at day 1 and day 4 postoperatively. The results were related to perioperative myocardial infarction (POMI), diagnostically based on ECG-changes, as well as to other perioperative variables. Cardiac surgery resulted in increased levels of S-TnT day 1 in all patients, and the level of this increase was dependent on the type of surgical procedure performed and the duration of cardiac perioperative ischaemia. Similar results were observed for serum creatine kinase isoenzyme (mass determination) (S-CKMB), but differences were generally less well correlated with other perioperative variables. At day 1, patients with POMI had higher levels of S-TnT as well as S-CKMB when compared to patients without POMI. At day 4, most patients still had elevated levels of S-TnT, but the difference in S-TnT levels between patients with POMI and patients without POMI was more pronounced. In contrast, the levels of S-CKMB were essentially normalized in both groups. Measurements of S-TnT at day 4 appears to be of significant value in diagnosing POMI. However, most of the patients without POMI had increased levels of S-TnT at day 4, suggesting that some irreversible operatively induced myocardial damage had occurred. Thus, even at a late postoperative stage the perioperative duration of ischaemia and type and extent of the surgical procedure should be taken into consideration.
Eikvar et al. (Sat,) studied this question.