Temporal Trends in Diagnostic Testing Patterns for Wild-Type Transthyretin Amyloid Cardiomyopathy in the Medicare Fee-for-Service Population

Wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM) is frequently misdiagnosed or diagnosed late in the disease course. ATTRwt-CM can be diagnosed invasively through tissue biopsy, but current diagnostic recommendations indicate technetium-99m pyrophosphate (^99mTc-PYP) bone scintigraphy is an acceptable noninvasive alternative. The relative use of these confirmatory diagnostic tests in routine clinical practice is unknown. A retrospective observational study assessed temporal trends in biopsy and ^99mTc-PYP scintigraphy and differences in patient characteristics using in/outpatient claims data from the US Medicare fee-for-service database. Claims prevalence for biopsy alone (≥1 claim for cardiac/extracardiac biopsy), imaging alone (≥1 claim for ^99mTc-PYP scintigraphy), and both tests and patient demographic, geographic, and clinical characteristics were examined. Of patients (n = 1226) receiving an ATTRwt-CM diagnostic code, 29%, 47%, and 24% were diagnosed by biopsy alone, ^99mTc-PYP scintigraphy alone, and both tests, respectively. Patients with claims for ^99mTc-PYP scintigraphy alone were older than those with claims for biopsy alone (79.9 vs 76.5; p <0.001). Fewer patients in the southern United States and more patients in the northeastern United States had claims for ^99mTc-PYP scintigraphy alone than biopsy alone (p <0.001). There was a temporal trend toward more claims for ^99mTc-PYP scintigraphy alone (odds ratio 1.21; p <0.001) and both tests (odds ratio 1.10; p = 0.008) versus biopsy alone. From 2017 to 2019, claims increased for ^99mTc-PYP scintigraphy alone. In conclusion, these data suggest a growing preference for the noninvasive imaging technique, which has high sensitivity/specificity, usability, and accessibility and may help facilitate earlier disease diagnosis. United States regional differences in the use of ^99mTc-PYP scintigraphy highlight the need for education initiatives.