Thoracic Fat Pad Biopsy in Cardiac Amyloidosis: Diagnostic Yield in an Afro-Caribbean Population

Aims: Cardiac amyloidosis (CA) is associated with amyloid infiltration of extra-cardiac tissue, which may occur at early stages of the disease. This study evaluates the diagnostic utility of thoracic fat pad biopsy obtained during pacemaker or ICD implantation as an alternative to standard diagnostic criteria for systemic amyloidosis. Methods and results: This exploratory, retrospective study included 27 patients with suspected or diagnosed cardiac amyloidosis (CA) who underwent pacemaker or defibrillator therapy. Of these, 16 patients were confirmed to have CA (15 with technetium-labeled bisphosphonate bone scintigraphy and 1 with protein electrophoresis and echocardiographic findings), while 11 were confirmed to be CA-negative. Thoracic fat pad biopsy demonstrated a specificity of 100% but a sensitivity of only 31%. Among patients with transthyretin (ATTR)-CA, sensitivity remained similarly low at 27%. These results are consistent with prior findings on abdominal fat pad biopsy in ATTR-CA, highlighting the limited diagnostic yield of this method. Conclusion: Thoracic fat pad biopsy cannot be recommended as a standard diagnostic tool for CA, particularly in ATTR-CA, due to its poor sensitivity. However, in AL (amyloid light-chain) amyloidosis, this minimally invasive procedure may aid diagnosis without additional invasive interventions.