Prognostic Impact of the Increase in Cardiac Troponin Levels during Tafamidis Therapy in Patients with Transthyretin Cardiac Amyloidosis

Background: Recent clinical trials have demonstrated that tafamidis (Pfizer Inc., New York, NY, USA) reduced all-cause mortality and the number of cardiovascular hospitalizations compared with placebo in patients with transthyretin cardiac amyloidosis. However, the optimal surrogate markers during tafamidis treatment remain unknown. Methods: Consecutive patients with transthyretin cardiac amyloidosis who received tafamidis in our institute between May 2019 and December 2022 were retrospectively evaluated. The prognostic impact of an increase in troponin I levels during tafamidis therapy was evaluated. Results: A total of 18 patients (median age 77 years, 84% male) were included. For 14-month tafamidis therapy on median, cardiac troponin I levels increased in five patients. The cumulative incidence of all-cause hospitalization was significantly higher in the troponin-increased group than in the others (100% versus 33%, p < 0.0001). Troponin increase was independently associated with the cumulative incidence of all-cause hospitalization with an adjusted hazard ratio of 5.14 (95% confidence interval 1.02–25.9, p = 0.048). Conclusions: The increase in cardiac troponin levels may be a reasonable surrogate marker of response to tafamidis therapy in patients with transthyretin cardiac amyloidosis.