Baseline Predictors of Adverse Outcomes for Transthyretin Amyloidosis Cardiomyopathy Patients Treated and Untreated with Tafamidis: A Canadian Referral Center Experience

<b>Background:</b> Tafamidis is a costly therapy that improves outcomes for patients with transthyretin amyloidosis cardiomyopathy (ATTR-CM), although significant knowledge gaps exist for predicting longer-term response to treatment. The purpose of this study was to examine baseline predictors of adverse outcomes and their association with tafamidis treatment in comparison with those untreated in a clinical cohort from a Canadian ATTR-CM referral center. <b>Methods:</b> Patients with a confirmed diagnosis of ATTR-CM were included. Multivariable modeling was used to identify baseline variables associated with the primary outcome of all-cause mortality and secondary outcomes of cardiovascular mortality or hospitalization. Cox proportional hazard and competing risk analyses were used, with tafamidis modeled as a time-varying covariate. <b>Results:</b> In total, 139 ATTR-CM patients were included, with a median age of 80.9 years [74.3-86.6 years], from 2011 to 2022. The mean follow-up was 2.9 ± 1.8 years. Eighty (55%) patients were treated with tafamidis. All-cause mortality and cardiovascular mortality alone were associated with the following baseline variables: age, clinical frailty scale, systolic blood pressure, renal function, and right ventricular size and function (all <i>p</i> < 0.05), with no identified interactions with tafamidis treatment. Only baseline renal function was associated with cardiovascular hospitalization (<i>p</i> < 0.05). <b>Conclusion:</b> Important baseline variables associated with adverse ATTR-CM disease outcomes included renal function, systolic blood pressure, frailty, and right ventricular size and function. The risk factors were independent of treatment with tafamidis. These findings may help improve risk stratification for determining eligibility for ATTR-CM therapies.