9-Year Serial CMR Monitoring of Cardiac AL Amyloidosis Regression After Teclistamab.

BACKGROUND: Cardiac amyloid light-chain (AL) amyloidosis carries a poor prognosis and is considered largely irreversible once symptomatic. Long-term serial cardiovascular magnetic resonance (CMR) data following B-cell maturation antigen-directed therapy are lacking. CASE SUMMARY: A 64-year-old man with biopsy-proven cardiac AL amyloidosis achieved sustained hematologic complete response after teclistamab following failure of 4 prior lines including daratumumab. Eleven CMR examinations over 9 years documented a biphasic trajectory: progressive infiltration through 2020 (left ventricular mass 186 g, wall thickness 18 mm, global longitudinal strain -4.8%), followed by sustained structural and functional regression through 2025 (left ventricular mass 127 g, wall thickness 13 mm, global longitudinal strain -13.7%). DISCUSSION: This represents the longest serial CMR follow-up in cardiac AL amyloidosis reported to date, demonstrating that cine-derived parameters reliably track cardiac regression in real-world conditions. Native T1 normalized while extracellular volume fraction (ECV) paradoxically increased, suggesting persistent fibril burden beyond hematologic clearance. TAKE-HOME MESSAGE: Serial CMR with cine-derived parameters provides robust longitudinal monitoring of cardiac AL amyloidosis regression following novel plasma cell-directed therapy, even without systematic contrast enhancement.