Abstract / Summary
Background Several disease-modifying agents for transthyretin amyloid cardiomyopathy (ATTR-CM) have been investigated, but differences in trial design and background stabilizer use complicate interpretation of their efficacy. This meta-analysis assessed their efficacy overall and by background stabilizer use. Methods PubMed, Embase, and the Cochrane Library were searched through September 2026 for phase III randomized, placebo-controlled trials of disease-modifying therapy in ATTR-CM. Primary endpoints were all-cause mortality, 6-minute walk distance (6MWD), Kansas City Cardiomyopathy Questionnaire-Overall Summary (KCCQ-OS) score, and N-terminal pro-B-type natriuretic peptide (NT-proBNP), pooled with a random-effects model. Treatment effects were compared between the monotherapy and baseline stabilizer strata using a mixed-effects model. Results Five trials (ATTR-ACT, APOLLO-B, ATTRibute-CM, HELIOS-B, CARDIO-TTRansform; N=3497) were included. Disease-modifying therapy reduced all-cause mortality (risk ratio, 0.76; 95% confidence interval [CI], 0.66-0.87; I2=0%) and improved 6MWD (pooled standardized mean difference [SMD], 0.43; 95% CI, 0.20-0.67), KCCQ-OS score (SMD, 0.37; 95% CI, 0.19-0.55), and NT-proBNP (SMD, -0.53; 95% CI, -0.89 to -0.18). The mortality benefit was similar whether therapy was given alone or added to a background stabilizer (pooled risk ratio, 0.77 vs. 0.71; P for interaction = 0.59), but treatment effects on 6MWD (pooled SMD, 0.49 vs. 0.14), KCCQ-OS score (0.44 vs. 0.07), and NT-proBNP (-0.65 vs. -0.13) were smaller among patients receiving a background stabilizer (P for interaction = 0.012, <0.001, and 0.029, respectively). Conclusion Disease-modifying treatments reduced all-cause mortality and favored functional capacity, health status, and NT-proBNP outcomes in patients with ATTR-CM. Exploratory subgroup analyses showed smaller treatment effects on 6MWD, KCCQ-OS score, and NT-proBNP among patients receiving a background stabilizer, with no statistically significant difference in the mortality effect according to baseline stabilizer use.