ATTR-CM in Patients With Clinically Significant Plasma Cell Dyscrasias: A Case Series Highlighting Diagnostic Challenges.

BACKGROUND: Suspicion and diagnosis of transthyretin cardiac amyloidosis (ATTR-CM) in patients with clinically significant plasma cell disorders is challenging. Timely identification of both light chain (AL) and ATTR-CM is essential for optimizing patient outcomes. CASE SUMMARY: We report 6 patients with clinically significant plasma cell disorders diagnosed with concomitant ATTR (4 variant and 2 wild-type), in whom genetic testing and endomyocardial biopsy led to accurate diagnosis. DISCUSSION: This case series highlights the diagnostic pitfall of assuming patients with suspected cardiac amyloidosis and clinically significant plasma cell dyscrasias have AL-CM. Tissue confirmation is required to accurately subtype cardiac amyloidosis in patients with plasma cell dyscrasias. Genetic testing is a valuable adjunct to refine pretest probability of ATTR-CM, particularly when diagnosis is uncertain or biopsy is deferred.