Tracking treatment response in cardiac AL amyloidosis with native-T1 mapping

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background Cardiac magnetic resonance (CMR) derived extracellular volume (ECV) mapping has demonstrated utility in determining the cardiac response to chemotherapy in systemic AL amyloidosis, but concomitant renal dysfunction is a common contraindication for the required gadolinium contrast. Objectives To assess the ability of native-T1 mapping to measure the cardiac response to treatment, and assess the association between changes in native-T1 and prognosis. Methods We studied 221 patients who underwent cardiac magnetic resonance (CMR) scans at diagnosis and a repeat scan following chemotherapy. Results At 6-months a reduced native-T1 of ≥50ms occurred in 8(4%) patients, all of whom had a good haematological response; by contrast an increased native-T1 of ≥50ms occurred in 42(23%) patients, most of whom had a poor haematological response (n=27,68%). At 12-months, a reduced native-T1 occurred in 24(15%) patients, all of whom had a good haematological response, and was associated with a reduction in median N-terminal pro-brain natriuretic peptide (NT-proBNP) (2638ng/L vs 432ng/L,P<0.001) and E/e’ (14.9±6.8 vs 12.0±5.2, P=0.007), improved longitudinal strain (−14.8±4.0 vs −16.7±4.0, P=0.004) and reduction in both T2 (52.3±2.9 vs 49.4±2.0, P<0.001) and ECV (0.47±0.07 vs 0.42±0.08, P<0.001); increased native-T1 occurred in 24(15%) patients, most of whom had a poor haematological response (n=17,71%) and was associated with an increased median NT-proBNP (1622ng/L vs 3150ng/L, P=0.007), reduced ejection fraction (65.8±11.4% vs 61.5±12.4%, P=0.009) and both increased T2 (52.5±2.7 vs 55.3±4.2, P<0.001) and ECV (0.48±0.09 vs 0.56±0.09, P<0.001). Change in native-T1 at 6-months predicted mortality even after adjusting for haematological response and NT-proBNP response (HR=2.41,95%CI[1.36–4.27],P=0.003). Conclusion Changes in myocardial native-T1 in response to treatment, are reflected in changes in the traditional markers of the cardiac response provide a powerful independent predictor of mortality. Change in native-T1 represents an important addition to the standard armamentarium of amyloid assessment, and provides an alternative measure of the cardiac treatment response, that not only limits exposure of patients to contrast but could also have implications on clinical workflow by reducing scan time.