Underutilization Of Appropriate Testing For Transthyretin Amyloidosis Despite Suspicious Clinical & Echocardiographic Findings

Introduction: Both hereditary (hATTR) and wild-type (wtATTR) transthyretin amyloidosis are under-recognized causes of cardiomyopathy (CM) and heart failure. Certain findings on Transthoracic Echocardiography (TTE) and cardiac Magnetic Resonance Imaging (cMRI) are suggestive but not diagnostic of ATTR. Although biopsy historically has been the gold standard for diagnosis, patients can be diagnosed with the highly sensitive and specific technetium-99m pyrophosphate scan (Tc-99m PYP). Genetic testing is recommended to confirm hATTR in patients diagnosed with ATTR cardiac amyloidosis. Despite growing awareness of this condition, many cases remain undiagnosed. This study evaluated if patients with TTEs concerning for infiltrative CM received appropriate diagnostic testing for ATTR-CM. Methods: Our echocardiography registry was queried from January 2011 to March 2020 for patients with our echo lab’s embedded infiltrative CM code. Data on demographics, comorbidities, TTE variables, cMRI results, PYP scans, genetic testing and biopsy results were retrieved from electronic medical records. Thorough manual chart review excluded other causes of CM. Data was expressed as mean ± SD and n (%). Results: We retrieved 510 patients (mean age 64 ± 16 years; 43% female) with TTEs suspicious for infiltrative CM revealing a mean interventricular septal diameter (IVSd) of 1.6 ± 0.3 cm. Only 67 (13%) patients underwent cMRI with 11 (16%) suggestive of cardiac amyloidosis. Of the patients with suspicious TTEs, 16 (3.1%) had PYP scans and 24 (4.7%) had tissue biopsy, with positive results in 7 (44%) and 11 (46%), respectively. Genetic testing in 31 (6%) patients revealed known hATTR mutations in 2 (6.5%) patients. Cardiac amyloidosis was diagnosed in 23 (4.5%) with 11 ATTR (2 hATTR), 5 amyloid light chain, and 7 unknown subtype. Conclusion: Despite clinical and TTE findings suspicious for ATTR-CM, many patients did not undergo appropriate confirmatory testing (see Figure 1).