Cardiac troponin T: A noninvasive marker for heart transplant rejection?

Background: Diagnosis of acute rejection remains a major concern in heart transplant recipients. Currently, endomyocardial biopsy is the gold standard for detecting rejection. Given the risks and cost of endomyocardial biopsy, a noninvasive marker for rejection would be ideal. Cardiac troponin T (cTnT) is an established marker of myocyte damage, and a rat transplantation model of heart transplant rejection has suggested that cTnT may be of value in detecting rejection. Methods: The cTnT levels were measured in 90 transplant recipients (67 men and 23 women) at the time of endomyocardial biopsy. There were a total of 256 cTnT levels and 256 biopsy samples. The cTnT levels were compared by use of International Society of Heart and Lung Transplantation rejection grades. Results: Only one of the 12 grade 3 biopsy specimens had a corresponding elevated cTnT level. Of the 29 biopsy specimens with myocyte necrosis (grade 2 or grade 3), three had a corresponding elevated cTnT. The cTnT levels were elevated during the first 1 to 2 months after transplantation. There was no correlation between ischemic time and cTnT levels. Conclusion: CTnT is an insensitive marker of acute rejection, both early and late after heart transplantation. Elevation of cTnT after transplantation does not seem to be directly related to ischemic time.