Noncontrast Magnetic Resonance for the Diagnosis of Cardiac Amyloidosis.

Objectives: This study aimed to assess the diagnostic use of native T1 to detect cardiac amyloidosis (CA) in a large prospective cohort of patients referred for suspected systemic amyloidosis.
Background: CA is a progressive and fatal underdiagnosed cause of heart failure. Cardiovascular magnetic resonance (CMR) has emerged as an extremely useful test for the non-invasive diagnosis of CA, but administration of contrast is still required to make a diagnosis.
Methods: In this study, 868 patients with suspected CA referred between 2015 and 2017 underwent CMR with late gadolinium enhancement (LGE), T1 mapping, and an array of clinical investigations.
Results: The final diagnosis was cardiac light-chain (AL) amyloidosis in 222, cardiac transthyretin (ATTR) amyloidosis in 214, and no cardiac involvement in 427 cases. T1 was significantly elevated in both types of CA and this was associated with high diagnostic accuracy in the overall population (area under the curve, 0.93). A native T1 <1,036 ms was associated with 98% negative predictive value for CA whereas a native T1 >1,164 ms was associated with 98% positive predictive value for CA. We propose the use of these cut-offs to exclude or confirm CA and to restrict the administration of contrast only to patients with intermediate probability (native T1 between 1,036 and 1,164 ms), 58% of patients in this population.
Conclusions: Native myocardial T1 enables diagnosis of CA to be made without need for gadolinium contrast in a large proportion of patients with suspected systemic amyloidosis. We propose a diagnostic algorithm for non-contrast CMR applicable to patients with suspected amyloidosis.
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