Purpose: The aim of this study was to investigate quantitative cardiac magnetic resonance (CMR) tomography for the differential diagnosis of left ventricular (LV) hypertrophy, particularly for the identification of cardiac amyloidosis.

Background: CMR using T1 mapping allows myocardial tissue characterization. Specific cut-off values in 3.0 tesla scanners to differentiate myocardial entities among patients with LV hypertrophic phenotype have not been established.

Methods: We retrospectively identified patients in the CMR database of Leipzig university hospital with increased LV wall thickness (≥12mm diameter at end-diastole) who were referred for the evaluation of LV hypertrophy or ischemia between 2017 and 2020 on a 3T scanner. Diagnosis of cardiac amyloidosis was made by either biopsy or non-invasively by bone scintigraphy and screening for monoclonal gammopathy. Patients with suspected or confirmed myocarditis were excluded. T1 mapping was measured as global mean value from 3 short axis slices of the LV.

Results: 128 consecutive patients were included in the study. 31 subjects without evidence of structural heart disease served as healthy control. The final diagnosis was cardiac amyloidosis in 24 patients (5 patients with light-chain (AL), 18 with transthyretin (ATTR) amyloidosis, 1 undetermined), hypertrophic cardiomyopathy in 24, and hypertensive heart disease in 80 patients. Mean age of patients was 65±13years, 84% were male. LV mass was increased in patients with LV hypertrophy compared to healthy control (p<0.001). Native T1 values of the LV myocardium were higher in patients with cardiac amyloidosis (1409±59ms, p<0.0001 vs. all other groups) compared to healthy control (1225±21ms), patients with hypertrophic cardiomyopathy (1263±43ms) and hypertensive heart disease (1257±41ms) (Figure). Patients with hypertrophic cardiomyopathy and hypertensive heart disease did not differ in their native T1 values, but both groups were increased compared to healthy control (p<0.01). Receiver operating characteristic analysis of native T1 values demonstrated an area under the curve for the detection of cardiac amyloidosis of 0.9954 (p<0.0001) vs. hypertrophic cardiomyopathy, hypertensive heart disease and healthy control. The optimal cut-off value was 1341ms, with a sensitivity of 96% and a specificity of 98%.

Conclusion: Native T1 mapping detects cardiac amyloidosis with high sensitivity and specificity among patients with LV hypertrophy. Prospective confirmation of these data is warranted.

Study ID: DRKS00022048