Myocardial T1 Mapping, Left Ventricular Parameters, and Cardiac Biomarkers in Wild-Type Transthyretin Amyloid Cardiomyopathy Before and After Tafamidis Treatment

Background: To further elucidate the clinical implications of myocardial T1 mapping with cardiac magnetic resonance (CMR) in transthyretin amyloid cardiomyopathy (ATTR-CM), we investigated the relationships of native myocardial T1 value (T1native) and extracellular volume fraction (ECV) with left ventricular (LV) parameters and cardiac biomarkers in ATTR-CM patients before and after tafamidis treatment. Methods and Results: We studied wild-type ATTR-CM patients who underwent baseline CMR with LV cine and T1 mapping techniques. T1native and ECV were derived from averaged values of base-to-apex LV myocardium. Cardiac biomarkers, including high-sensitivity cardiac troponin T (hs-cTnT) and N-terminal pro-B-type natriuretic peptide (NT-proBNP), were measured at baseline. In a subset of the patients, follow-up CMR was performed and cardiac biomarkers were remeasured 1 year after initiation of tafamidis treatment. Both T1native (n=66) and ECV (n=50) positively correlated with LV end-diastolic volume index, LV mass index, Ln (hs-cTnT), and Ln (NT-proBNP). T1native correlated negatively with LV ejection fraction. Multivariate analysis showed that Ln (hs-cTnT) independently correlated with increased T1native (beta=0.32; P=0.033). In the tafamidis follow-up group, changes in T1native (triangle T1native) (n=30) and ECV (n=21) after treatment (follow-up-baseline values) negatively correlated with their baseline values. triangle T1native positively correlated with triangle NT-proBNP concentration (r=0.45; P=0.013). Conclusions: T1native and ECV are comprehensive indicators of LV characteristics in wild-type ATTR-CM patients and may provide imaging-based evidence of meaningful changes after tafamidis treatment.