Abstract 9218: Troponin Elevation, Ischemic Electrocardiographic Changes and Prognosis after a Postoperative Myocardial Infarction

Abstract

Background: In the postoperative period the majority of myocardial infarctions are clinically silent and its diagnosis relies heavily on a biomarker elevation. Although an elevated troponin level following vascular surgery is associated with a poor long-term outcome, the utility of abnormal EKG changes as additional prognostic information is unclear. Methods: Single center registry of 435 patients undergoing high-risk vascular surgery at the Minneapolis VA Medical Center between January 2005 and December 2009. Blood was obtained in all patients in the first two days following vascular surgery and the troponin I levels were measured by the Dade Behring Dimension Analyzer. Those values that exceeded the URL were categorized as either LOW (+) (≥ the URL but < 3 times the URL) or HIGH (+) (≥ 3 times the URL). Electrocardiograms obtained before the operation and within the first 3 postoperative days were reviewed by 2 independent cardiologists and classified as ischemic (ST-segment depression, ≥ 2 mm T-wave inversion) or non-ischemic. Long-term survival was retrieved using BIRLS. Results: The mean age of the population was 68±8 and the most common vascular problem was an expanding abdominal aneurysm (49%). Eighty-one (18.6%) patients were classified as HIGH (+) and 104 (24%) as LOW (+) with regard to troponin values. Thirty-one (7%) patients had evidence of myocardial ischemia on electrocardiography. An increase in mortality was seen with incremental troponin values (p <0.001). However, the presence of electrocardiographic changes did not provide additional prognostic information to that conveyed by troponins in any category (p: 0.91, Figure). Conclusions: The requirement for an electrocardiographic correlate of myocardial ischemia to define a myocardial infarction appears to be insensitive in the post-operative period. Further, in the presence of a troponin elevation the incremental prognostic value of an ischemic ECG is minimal.