Prospective evaluation of the morbidity and mortality of wild-type and V122I mutant transthyretin amyloid cardiomyopathy: The Transthyretin Amyloidosis Cardiac Study (TRACS)

Abstract

TRACS sought to describe the clinical outcomes and disease progression of transthyretin (TTR) cardiac amyloidosis (ATTR) in an observational study. Clinical course is largely determined by disease type with ATTR categorized as wild-type (ATTRwt) or genetic-variant protein (ATTRm). Prospective data are lacking in the most common TTR mutation, V122I, present in approximately 3.5% of African Americans. Patients with ATTRwt (n = 18) and V122I ATTRm (n = 11) were longitudinally assessed every 6 months for up to 2 years by functional class assessments, biochemical markers, and echocardiography. At baseline, no differences in clinical characteristics, biomarkers, or echocardiographic parameters were noted between patients with ATTRwt and patients with ATTRm. After 15.5 ± 8 months, there were 11 deaths and 1 cardiac transplant, with higher mortality (73% vs 22%, P = .03) and cardiovascular hospitalization (64% vs 28%, P = .02) among patients with ATTRm. The median survival from diagnosis was 25.6 months for ATTRm vs 43.0 months for ATTRwt (P = .04). Univariate predictors of mortality included disease duration, heart rate ≥ 70 beats/min, baseline stroke volume, left ventricular ejection fraction <50%, and ATTRm status. For each 6-month increment, the mean 6-minute walk distance declined by 25.8 m, N-terminal pro b-type natriuretic peptide increased by 1,816 pg/mL, and left ventricular ejection fraction fell by 3.2%, for the entire cohort. In this prospective study, disease progression, morbidity, and mortality were observed in ATTR cardiomyopathy, particularly due to V122I, over a short duration. Given the prevalence of this mutation, further study of V122I in at-risk African American patients is warranted.