Kim, Antony Y.

Background: ATTR-CM is believed to have a relatively indolent course, with a median survival of ~5 years from heart failure symptoms; however, no data exist as to the rate of progression after disease diagnosis. ATTR-CM is associated with genetic variants, including V122I (present in ~ 3.5% of African Americans), or wild-type TTR (senile systemic amyloidosis - SSA). While there is no effective treatment other than heart transplantation, therapies designed to slow or halt amyloid deposition are in development. The purpose of this study was to characterize the natural history of ATTR-CM to support future therapeutic trials. Methods: Patients with ATTR-CM due to V122I (n = 11) and SSA (n = 18), were enrolled 10.4 ± 11.9 months after diagnosis (range: 0 – 60 months) and assessed every 6 months for up to two years by echocardiography and cardiac magnetic resonance imaging (CMR), with functional capacity assessed by 6-minute walk, and biochemical profile including cardiac troponins and NT-pro-B-type natriuretic peptide (BNP). Baseline data from the full cohort (n = 29), and available data from those completing the 12 month assessment (n = 15) are presented for this on-going study. Results : At baseline, both groups were similar in terms of gender, duration of disease from diagnosis, NYHA, troponin/NT-BNP, and echo or CMR-measured LV wall thickness. SSA patients were older (mean age 76 vs. 71y, P = 0.03), Caucasian (100% vs 0%, P < 0.001), with a history of atrial fibrillation (83% vs. 27%, p = 0.003). During a mean follow-up of 442 days (30–768), there have been 7 deaths (4 V122I; 3 SSA) and 1 cardiac transplantation (SSA), and 10 of 29 (34.5%) were hospitalized at least once (90% for cardiac reasons). For those subjects with a 12 month assessment, LV ejection fraction declined by echo (2.8 %) and CMR (12 %), with minimal changes in wall thickness. Increases were seen in NT-Pro-BNP (87%) and troponin (I: 186%; T: 70%). Worsening of NYHA class occurred in 43% of patients; 6-minute walk distance decreased by 19.2%. Conclusions : Despite reports of a relatively indolent course of ATTR-CM, preliminary data from this ongoing study are the first to demonstrate that quantifiable noninvasive parameters worsen over a 1 year follow up period and are associated with adverse clinical outcomes.