Tafamidis Helps More Heart Amyloid Patients Keep Their Walking Distance, Analysis Finds

Patients with transthyretin amyloid cardiomyopathy who took the drug tafamidis were more likely to hold onto their walking capacity over a year of treatment than patients given a placebo, and those who did so faced a markedly lower risk of dying in the following 18 months, according to a post hoc analysis of the phase 3 ATTR-ACT trial published on 27 August 2026 in the journal Cardiology and Therapy. The analysis, led by researchers including Ronald Witteles, Mazen Hanna, Martha Grogan, Perry Elliott and Pablo Garcia-Pavia, used the 6-minute walk test as its central yardstick of functional stability, a measure that has become one of the most closely watched indicators of disease trajectory in this progressive form of heart failure.

The disease shortens life expectancy and erodes cardiac function over time, and disease-modifying therapies are intended to slow that decline. Tafamidis is an oral transthyretin kinetic stabilizer taken once daily that works by holding the TTR protein in its stable shape, and it is approved for treating ATTR-CM in more than 50 countries worldwide. In the original ATTR-ACT trial, registered as NCT01994889, patients randomized to tafamidis showed a statistically significant reduction in mortality at 30 months compared with placebo, along with slower disease progression and improvements in patient-reported outcomes and quality of life.

The 6-minute walk test, in which clinicians simply measure how far a patient can walk on foot in six minutes, is an established indicator of functional stability or progression both in heart failure generally and in ATTR-CM specifically. In the primary ATTR-ACT results, tafamidis produced a significantly smaller decline in walking distance than placebo from month 6 onwards through the end of the study, with a p value below 0.001. The new analysis builds on earlier work showing that the magnitude of decline carries prognostic weight: a study by Ioannou and colleagues found that an absolute decline of more than 35 metres one year after baseline, or a relative decline of more than 5 percent of baseline walking distance, was associated with increased mortality, with hazard ratios of 1.80 and 1.89 respectively, both statistically significant. International expert consensus meetings have likewise suggested that a decrease of roughly 30 to 40 metres, evaluated every 6 to 12 months, should be treated as a marker of disease progression.

Those benchmarks shaped the design of the new post hoc analysis. The investigators included patients from ATTR-ACT who had been randomized to tafamidis meglumine 80 mg, the dose bioequivalent to tafamidis free acid 61 mg and the approved dose for ATTR-CM in the United States and the European Union, or to placebo, who were still alive at month 12, and who had walk test data at both baseline and month 12. That yielded 149 patients in each arm. Anyone whose walking distance had declined by 35 metres or less from baseline was classified as having functional stability, while anyone whose distance had fallen by more than 35 metres was classified as having progression. The 12-month and 35-metre cut-offs were chosen on the basis of the Ioannou study and international expert guidance.

The headline result was a shift in where patients landed on that divide. After 12 months of treatment, 64 percent of the tafamidis group, 96 of 149 patients, met the criterion for stability, compared with 53 percent of the placebo group, 79 of 149 patients. The researchers then tracked what happened to both groups over the subsequent 18 months, from month 12 to the end of the study at month 30. Median follow-up in that window was similar across subgroups, ranging from 17.6 to 17.9 months in the stability categories and somewhat more variable in the progression categories, particularly among placebo patients, where the lower quartile of follow-up reached only 10.1 months.

Mortality told a consistent story. During the follow-up period, all-cause mortality was lower among patients with 12-month walk test stability than among those with progression in both treatment arms: 12 percent versus 34 percent in the tafamidis group, and 28 percent versus 43 percent in the placebo group. Mortality was also numerically higher in the placebo subgroups than in the corresponding tafamidis subgroups. The sharpest contrast emerged among patients who had achieved stability: those taking tafamidis 80 mg had a 65 percent reduction in the risk of all-cause mortality compared with placebo, with a hazard ratio of 0.347 and a 95 percent confidence interval of 0.166 to 0.724, statistically significant at p = 0.0048. Among patients with progression, the reduction was not statistically significant. Notably, all-cause mortality in this analysis counted heart transplants and implantation of cardiac mechanical assist devices as events. Viewed from the other direction, among tafamidis-treated patients, stability itself conferred a 73 percent hazard reduction for death compared with progression, with a hazard ratio of 0.267 and p = 0.0006; the corresponding reduction with stability among placebo patients was not statistically significant.

Cardiovascular-related hospitalizations followed a parallel pattern. Across both treatment arms, both the incidence and the yearly rate of cardiovascular hospitalizations were lower in patients with walk test stability than in those with progression. In the tafamidis arm, hospitalization incidence was 41 percent in the stability group and 68 percent in the progression group, with model-adjusted annual rates of 0.65 and 1.19 respectively. In the placebo arm, incidence was 57 percent and 67 percent, with model-adjusted annual rates of 0.96 and 1.59. Among patients with stability, tafamidis produced a 32 percent reduction in the risk of cardiovascular hospitalization relative to placebo, with a risk ratio of 0.677, a 95 percent confidence interval of 0.500 to 0.916, and p = 0.0115. Among patients with progression, the 25 percent risk reduction was not statistically significant, with a risk ratio of 0.746 and p = 0.0585. When the analysis was flipped to ask how stability itself affected hospitalization risk within each arm, stability was associated with a 46 percent risk reduction in the tafamidis arm and a 40 percent risk reduction in the placebo arm, both statistically significant.

Statistically, the team used a Cox proportional hazard model with treatment as the main effect to evaluate time to all-cause mortality from months 12 to 30, and a Poisson regression model with treatment as the main effect to evaluate hospitalization rates over the same window, using events adjudicated by an endpoint adjudication committee. Both models were adjusted for transthyretin genotype, variant or wild-type, and for New York Heart Association functional class at baseline, with class I and II combined and class III analyzed separately, including missing classifications. Sensitivity analyses replaced the 35-metre absolute threshold with a relative decline of more than 5 percent from baseline. Significance consistency at the 0.05 level was confirmed for all comparisons of hazard ratios for mortality, and for three of the four comparisons of risk ratios for hospitalization.

The findings align with the broader evidence base. The authors note that their result, a higher proportion of patients maintaining functional stability on tafamidis, is in line with the primary ATTR-ACT analysis showing a slower decline in walking distance. They also point to the retrospective observational cohort study of 2,141 patients with ATTR-CM, of whom only 212 were receiving disease-modifying therapy, in which walk test data at baseline and one year were available for 1,118 patients and an absolute or relative decline in distance was associated with increased rates of both mortality and disease progression measured by several markers. In the new analysis, baseline characteristics were broadly balanced between the stability and progression subgroups, with two exceptions: among tafamidis-treated patients, significantly more patients in the stability group had diabetes mellitus, while significantly more patients in the progression group required outpatient diuretic intensification.

The authors are explicit that the analysis has limits. It involved a relatively small number of patients followed for a short duration, and it is exploratory by nature. Because it was restricted to patients alive at month 12, a necessary feature of the statistical approach, survival bias may have been introduced. Collapsing a continuous measure, the walking distance, into a binary stable-versus-progression classification may also discard prognostic information. The authors call for additional studies, including real-world studies of tafamidis treatment, to confirm the findings, and flag future analyses, including multivariate models using treatment and walk test progression as covariates, that could clarify whether changes in the walk test predict or mediate the drug’s effect on mortality and hospitalization. For now, the analysis suggests that a year of tafamidis kept more patients on the stable side of a clinically meaningful threshold, and that staying there was associated with substantially better outcomes over the following 18 months.

Subject of Research: A post hoc analysis of the ATTR-ACT trial examining functional stability on the 6-minute walk test in tafamidis-treated patients with transthyretin amyloid cardiomyopathy and its association with mortality and cardiovascular hospitalization

Article Title: Functional Stability Measured by Changes in the 6-min Walk Test in Patients Treated with Tafamidis Versus Placebo: Post hoc Analysis from ATTR-ACT

Article References: Witteles, R., Hanna, M. A., Grogan, M., Elliott, P., Wang, R., & Garcia-Pavia, P. (2026). Functional Stability Measured by Changes in the 6-min Walk Test in Patients Treated with Tafamidis Versus Placebo: Post hoc Analysis from ATTR-ACT. Cardiology and Therapy, 15(S1), 37-47. https://doi.org/10.1007/s40119-026-00471-7

Image Credits: AI Generated

DOI: 10.1007/s40119-026-00471-7

Keywords: tafamidis, transthyretin amyloid cardiomyopathy, ATTR-ACT, 6-minute walk test, functional stability, all-cause mortality, cardiovascular hospitalization, post hoc analysis, transthyretin stabilizer, heart failure, clinical trial, Functional