High-sensitivity Cardiac Troponin Is Not Associated with Acute Cellular Rejection after Heart Transplantation

Background. Acute cellular rejection (ACR) is common in the first year after cardiac transplantation, and regular surveillance endomyocardial biopsy (EMB) is required. An inexpensive, simple noninvasive diagnostic test would be useful. Prior studies suggest cardiac troponin (cTn) has potential as a "rule-out" test to minimize the use of EMB. Our aim was to determine whether a new high-sensitivity cardiac troponin I (hs-cTnI) assay would have utility as a "rule-out" test for ACR after heart transplantation. Methods. Blood samples at patient follow-up visits were collected and stored over a period of 5 y. Serum cTnI concentrations were measured using the ARCHITECT_STAThs-cTnI assay and compared with an EMB performed on the same day. Receiver-operator curve analysis based on mixed-effects logistic regression models that account for repeated measurements in individuals was performed to determine a serum troponin level below which ACR could be reliably excluded. Results. One hundred seventy patients had 883 serum hs-cTnI results paired to a routine surveillance EMB. Fifty-one (6%) EMB showed significant ACR (grade ≥2R). Receiver-operator curve analysis approximated the null hypothesis area under the curve 0.509 (95% CI, 0.428-0.591). Sub-analysis including repeated hs-cTnI levels in a single individual, and early (<3 mo) EMB also showed no diagnostic utility of hs-cTnI measurement (area under the curve 0.512). Conclusions. In the largest published study to date, we found no association between hs-cTnI concentration and the presence of significant ACR on surveillance EMB. Measurement of hs-cTnI may not be a useful technique for diagnosis or exclusion of ACR after heart transplantation.