The results indicated that cTnT levels were elevated in virtually all post-CABG patients, although only 2 percent actually met postoperative myocardial infarction criteria. Factors predicting cTnT elevation included the complexity of the initial coronary artery blockages, the number of grafts that were placed and the patients' immediate postoperative condition. While the near-universality of cTnT elevation made it a less useful indicator of heart attack, cTnT levels 10 times higher than the current consensus guidelines powerfully and independently predicted the risk of death and other postoperative complications, adding to the predictive power of risk-scoring models such as that developed by the Society for Thoracic Surgery.

"These findings imply that the diagnosis of regional post-CABG myocardial infarction should continue to be based largely on clinical judgment and angiographic demonstration of postoperative closure of a bypass graft, which is fortunately a rare situation," says Januzzi, who is an associate professor of Medicine at Harvard Medical School. "On the other hand, excessive diffuse myocardial injury - as reflected by significant cTnT elevation - may be more common than suspected; and cTnT does an excellent job of identifying those patients destined for complication in the postoperative period. This makes a strong case that troponin testing should be incorporated into overall post-CABG risk assessment, independent of its use for MI diagnosis."

Source: Massachusetts General Hospital