Abstract 4139964: Evolving Baseline Risk in Patients With Transthyretin Amyloid Cardiomyopathy: A Systematic Literature Review of Clinical Trials

Background: Transthyretin amyloid cardiomyopathy (ATTR-CM) is estimated to occur in 120,000 US adults and remains underdiagnosed. However, awareness of ATTR-CM has improved following the introduction of new diagnostic tools and disease-modifying treatments. Hence, patients (pts) enrolled in contemporary clinical trials could be at an earlier stage of the disease than pts in past clinical studies.

Aim: To assess temporal trends in the baseline risk of pts with ATTR-CM enrolled in clinical trials.

Methods: Embase, MEDLINE, CENTRAL, and conference websites were searched on November 23, 2023, for peer-reviewed articles and abstracts. Randomized and single-arm clinical trials examining treatments for ATTR-CM were included, and baseline characteristics and outcomes in pts treated with placebo (PBO) were compared across studies.

Results: We reviewed 39 publications derived from 4 randomized and 4 single-arm trials. Studies enrolled pts between 2008 and 2021, although 1 study (INOCARD, 2022) did not report years of enrollment. Several baseline characteristics were comparable across studies, including sex, age, race/ethnicity, genotype, and troponin I level. NYHA class at baseline varied with year of enrollment, with fewer NYHA class III pts in recent trials (Figure). Recent trials also showed a trend toward lower NT-proBNP levels (medians ranging from 1911-3178 pg/mL) and higher eGFR levels (means ranging from 54.7-69.0 mL/min/1.73 m ² ). In PBO groups, all-cause mortality (ACM) rates at 12 months dropped from 9% in ATTR-ACT (enrolled 2013-2015) to 6.9% in ATTRibute-CM (enrolled 2019-2020) and 5.6% in APOLLO-B (enrolled 2019-2021); ACM rates at 30 months dropped from 42.9% in ATTR-ACT to 25.7% in ATTRibute-CM.

Conclusions: This systematic review found that disease-modifying treatments and diagnostic advances have led to earlier diagnosis of pts with ATTR-CM. Recent clinical trials appear to have enrolled pts with a better prognosis. Comparisons of results across these trials are limited and should acknowledge the potential impact of variability in baseline risks among trial populations.