Prevalence of ATTR-CA and high-risk features to guide testing in patients referred for TAVR

Purpose: Transthyretin cardiac amyloidosis (ATTR-CA) is thought to be prevalent in patients with severe aortic stenosis (AS) who are referred for transcatheter aortic valve replacement (TAVR). However, prior studies were published when TAVR was only offered to elderly, inoperable, and high-risk patients. The aim of this study was to reevaluate the prevalence of ATTR-CA in a contemporary TAVR population and identify high-risk features to guide referral for technetium-99 pyrophosphate scan (99mTc-PyP scan) screening.

Methods: Patients seen in a multidisciplinary TAVR clinic for severe AS 70 years and older were referred for a 99mTc-PyP scan to evaluate for ATTR-CA. The primary outcome was the percent with a positive scan. The discriminatory ability of high-risk features was assessed to develop a more judicious screening system.

Results: Over the study period, 380 patients underwent screening, and 20 patients (5.3%) had a positive scan, with 17 patients having confirmed ATTR-CA, 1 patient deferring confirmatory testing (combined 4.7%), 1 having light chain amyloidosis, and 1 negative on biopsy. Compared to other patient and echocardiographic measures, elevated NT-pro BNP (> 1000 ng/L) was the best discriminator on who should be referred for 99mTc-PyP scan screening, with a sensitivity of 90% and a negative predictive value of 99%.

Conclusion: The prevalence of ATTR-CA may be lower in a contemporary TAVR population due to its expanded indication for low-risk patients. NT-pro BNP is a simple test that can improve screening yield and more judiciously guide screening for ATTR-CA in this at-risk population. Comparison of the original versus the proposed algorithm.