1028-63 Cardiac Troponin T as a Marker for Perioperative Myocardial Ischemia in Noncardiac Surgical Patients

Abstract

Episodes of perioperative myocardial ischemia (PMI) occur in 18 to 74% of noncardiac surgical patients with or at risk for coronary artery disease (CAD). PMls correlate with adverse postoperative cardiac outcome. To determine the diagnostic value of cardiac troponin T(TnT) in PMI, we studied 28 patients (63.9 ± 8.9 years) undergoing peripheral vascular surgery (n = 16) or carotid endarterectomy (n = 12). Patients included had either documented CAD (n = 16) or two (n = 7) or more (n = 5) risk factors (age >65 years, smoking. diabetes mellitus. hypertension, or hypercholesterolemia >240 mg/dL). Patients with uninterpretable ECG for PMI were excluded. 12-lead ECG recordings and blood sampling for measurement of CK-MB activity and TnT levels (ELISA troponin 1. Boehringer Mannheim, Germany) were carried out preoperatively, and immediately, 20 h, 48 h, 72 h, and 84 h postoperatively. ECG recordings were analysed by an independent blinded cardiologist for signs of PMI (new ST segment depression >0.1 mV 60 ms after the J point, new T inversion). We found an overall incidence of ECG documented PMI of 54% (n = 15), 93% occuring immediately postoperatively. Patients undergoing peripheral vascular surgery developed significantly less PMI than carotid surgical patients (38% vs. 75%; p < 0.05, Fisher's Exact test). TnT levels >0.1 μg/L were found in 80% (n = 12) of patients with PMI (ECG). Only one patient without ECG-documented PMI had TnT levels >0.1 μg/L. Thus, comparing a TnT cut off level of 0.1 μg/L with intermittent 12-lead ECG recording, we found a sensitivity of 80% and a specifity of 92%. We were unable to detect elevated levels of CK-MB in any patient (tab.). overall (n = 28) per. vase. surg. (n = 16) carotid surg. (n = 12) CK-MB >6 U/L 0 0 0 ECG(PMI) 15(54%) 6 (38%) 9(75%) TnT >0.1 μg/L 13(46%) 5(31%) 8(67%) In contrast to CK-MB, TnT is a specific and sensitive marker of PMI in patients with or at risk for CAD undergoing noncardiac surgery.