Tafamidis treatment significantly reduces the risk of recurrent cardiovascular-related hospitalisation in patients with early stage transthyretin amyloid cardiomyopathy

Background The clinical efficacy of tafamidis in patients with transthyretin amyloid cardiomyopathy (ATTR-CM) was demonstrated during the phase 3, multinational, randomised, placebo-controlled Tafamidis in Transthyretin Cardiomyopathy Clinical Trial (ATTR-ACT).(1) In ATTR-ACT, the risk of any cardiovascular (CV)-related hospitalisation was significantly reduced among patients who received tafamidis meglumine 80 mg (the approved dose) vs placebo (relative risk ratio 0.70 [95% CI 0.57, 0.85]; P=0.0005).(2) The benefit of tafamidis treatment was largest among patients with New York Heart Association (NYHA) class I/II vs III symptoms at baseline.(1,3,4) Purpose ATTR-CM is a progressive disease with a natural history that typically includes an increasing frequency of CV-related hospitalisation as the condition worsens. This post hoc analysis adds to current knowledge by evaluating the risk of recurrent (≥1) CV-related hospitalisation by baseline NYHA class in ATTR-ACT patients taking the approved dose of tafamidis or placebo. Methods Patients aged 18 to 90 years with biopsy-confirmed wild-type or variant ATTR-CM and NYHA class I-III symptoms took part in ATTR-ACT between 2013 and 2018. During the trial, the cause of hospitalisation was adjudicated by an independent committee. The hazard ratio (HR) for first CV-related hospitalisation was calculated using a Cox proportional hazards model. The HR for recurrent CV-related hospitalisation was calculated using the Liu-Wei-Yang-Ying (LWYY; also known as the modified Anderson-Gill) model. Models compared tafamidis meglumine 80 mg vs placebo and adjusted for transthyretin genotype (wild-type or variant). In the overall population, the LWYY model was also adjusted for baseline NYHA class. Results The frequency of adjudicated CV-related hospitalisations during ATTR-ACT by NYHA class are shown in the Figure. Across patients who were NYHA class I-III at baseline, the risk of recurrent CV-related hospitalisation was 37% lower in those who received tafamidis vs placebo treatment (HR 0.627 [95% CI 0.463, 0.848]; P=0.0025; Table). Among those who were NYHA class I/II at baseline, a lower proportion of tafamidis- vs placebo-treated patients (44% vs 61%) had ≥1 CV-related hospitalisation. The risks of first and recurrent CV-related hospitalisation were 40% (HR 0.601 [95% CI 0.420, 0.861]; P=0.0055) and 55% (HR 0.449 [95% CI 0.305, 0.661]; P<0.0001) lower with tafamidis vs placebo treatment. Consistent with the survivor bias previously observed in ATTR-ACT,(1-4) the risk of recurrent CV-related hospitalisation was statistically similar in tafamidis- and placebo-treated patients who were NYHA class III at baseline (HR 1.113 [95% CI 0.688, 1.799]; P=0.6624). Conclusions Building on previous findings, this analysis found the risk of recurrent CV-related hospitalisation to be reduced by tafamidis meglumine 80 mg treatment in patients with early stage ATTR-CM.