Effect of Timely Availability of TTR-Stabilizing Therapy on Diagnosis, Therapy, and Clinical Outcomes in ATTR-CM

Abstract

Background: Tafamidis reduces cardiovascular morbidity and mortality in transthyretin amyloid cardiomyopathy (ATTR-CM), yet availability and access to therapy vary. Objective: To determine how availability and access to tafamidis impact time-to-diagnosis, time-to-therapy, and cardiovascular outcomes in ATTR-CM. Methods: Ninety-one consecutive ATTR-CM (~97% wt-TTR) patients diagnosed between June 2019 and June 2021 were evaluated for tafamidis. Access to therapy was regulated by compassionate use [n(CU) = 42] prior to, and insurance [n(IA) = 49] after regulatory approval. Results: Tafamidis was started in 37/42 (88.1%), and 39/49 (79.6%) patients, respectively. At diagnosis, ATTR-CM disease stage (≤stage 2: 88.2% vs. 90.9%, p = 0.92) was similar between groups. Timely access (after tafamidis approval) reduced the median time from first presentation to diagnosis from 6.2 (IQR: 1.3–28.9) to 2.4 (0.7–21.7) months, and from first presentation to therapy from 24.4 (10.7–46.8) to 11.8 (6.4–32.4) months. While RV function significantly worsened between diagnosis and therapy initiation in CU patients diagnosed before tafamidis approval (S’-velocity 10.0 ± 2.2 to 9.2 ± 2.2 cm/s; p = 0.018; TAPSE 17.3 ± 4.7 to 15.7 ± 3.9 mm, p = 0.008), it remained unchanged in IA patients (S’-velocity 9.6 ± 2.6 to 9.4 ± 2.3 cm/s; p = 0.83; TAPSE 15.6 ± 4.2 to 16.3 ± 3.1 mm, p = 0.45). After a median follow-up of 42.3 and 24.9 months in CU and IA patients, respectively, timely availability was associated with a reduction in annual heart failure hospitalizations (0.40 vs. 0.16 per patient, p < 0.001) and improved MACE-free survival (HR = 0.51; 95%CI: 0.26–1.00; p = 0.051). Timely diagnosis (<12-months) prolonged MACE-free survival (HR = 0.424; 95%CI: 0.22–0.81; p = 0.004), and reduced HFH (HR = 0.40; 95%CI: 0.19–0.81); p = 0.011) and all-cause mortality (HR = 0.29; 95%CI: 0.11–0.74); p = 0.009). Conclusions: Availability of tafamidis improves diagnostic efficacy in ATTR-CM patients. Timely diagnosis and initiation of therapy reduces adverse cardiovascular events.