Native T1 Mapping in the Diagnosis o Cardiac Allograft Rejection A Prospective Histologically Validated Study

OBJECTIVES This study aimed to determine the role of T-1 mapping in identifying cardiac allograft rejection. BACKGROUND Endomyocardial biopsy (EMBx), the current gold standard to diagnose cardiac allograft rejection, is associated with potentially serious complications. Cardiac magnetic resonance (CMR)-based T-1 mapping detects interstitial edema and fibrosis, which are important markers of acute and chronic rejection. Therefore, T-1 mapping can potentially diagnose cardiac allograft rejection noninvasively. METHODS Patients underwent CMR within 24 h of EMBx. T-1 maps were acquired at 1.5-T. EMBx-determined rejection was graded according to International Society of Heart and Lung Transplant (ISHLT) criteria. RESULTS Of 112 biopsies with simultaneous CMR, 60 were classified as group 0 (ISHLT grade 0), 35 as group 1 (ISHLT grade 1R), and 17 as group 2 (2R, 3R, clinically diagnosed rejection, antibody-mediated rejection). Native T-1 values in patients with grade 0 biopsies and left ventricular ejection fraction >60% (983 +/- 42 ms; 95% confidence interval: 972 to 994 ms) were comparable to values in non-transplant healthy control subjects (974 +/- 45 ms; 95% confidence interval: 962 to 987 ms). T-1 values were significantly higher in group 2 (1,066 +/- 78 ms) versus group 0 (984 +/- 42 ms; p = 0.0001) and versus group 1 (1,001 +/- 54 ms; p = 0.001). After excluding patients with an estimated glomerutar filtration rate <50 ml/min/m(2), there was a moderate correlation of log-transformed native T-1 with high-sensitivity troponin T (r = 0.54, p < 0.0001) and pro-B-type natriuretic peptide (r = 0.67, p < 0.0001). Using a T-1 cutoff value of 1,029 ms, the sensitivity, specificity, and negative predictive value were 93%, 79%, and 99%, respectively. CONCLUSIONS Myocardial tissue characterization with T-1 mapping displays excellent negative predictive capacity for the noninvasive detection of cardiac allograft rejection and holds promise to reduce substantially the EMBx requirement in cardiac transplant rejection surveillance. (C) 2019 by the American College of Cardiology Foundation.