Effect of tafamidis on left atrial function in patients with transthyretin amyloid cardiomyopathy

Abstract Background Transthyretin amyloid cardiomyopathy (ATTR-CM) is characterized by the functional and structural consequences of amyloid infiltration predominantly within the ventricles, causing biventricular wall thickening. Amyloid infiltration can be observed in left atrium in ATTR-CM, however, the association of left atrial (LA) myocardial function with cardiovascular events and changes in LA myocardial function with tafamidis administration have not been elucidated. Purpose The aim of this study was to identify the association between baseline LA reservoir function evaluated by left atrial reservoir strain and cardiovascular events. Furthermore, monitoring the LA reservoir function before and after tafamidis administration, we also investigated the baseline factors associated with changes in LA reservoir function in patients with ATTR-CM. Methods We studied 55 patients with biopsy-proven ATTR-CM who were started on tafamidis in our institution between July 2019 and December 2022 (age: 76 ± 2 years, male: 93%). The primary endpoint was defined as hospitalization for heart failure or cardiovascular death during a median follow-up period of 28 ± 4 months after tafamidis administration. Furthermore, we assessed the factors associated with changes in LA function before and 25 ± 3 months after tafamidis administration for 49 patients who underwent sufficient follow-up echocardiography. Results During the follow-up period, 8 patients had cardiovascular death or cardiovascular hospitalization. The Kaplan-Meier curve indicated that the occurrence of cardiovascular events for patients with LA strain ≥ the median 8.6% was significantly lower than for those with LA strain < 8.6% (log-rank P =0.002; Figure A). Furthermore, comparing LA strain before and after tafamidis administration, the group with worsening LA strain tended to be older (79.0 ± 2.0 years vs. 73.6 ± 3.3 years, P=0.004), have higher brain natriuretic peptide (350 ± 83 pg/mL vs. 199 ± 47 pg/mL, P=0.003), have lower global longitudinal strain (GLS) (9.8 ± 1.4 % vs. 12.6 ± 1.6 pg/mL, P=0.008), and higher relative apical longitudinal strain index (1.63 ± 0.4 % vs. 1.14 ± 0.2 %, P=0.021). The multivariate logistic regression analysis was that age, GLS and relative apical longitudinal strain index were the independent determinants for deterioration of LA strain after tafamidis administration (Figure B). Conclusion In our study, baseline LA reservoir function was found to be closely associated with cardiovascular events after tafamidis administration, while age, GLS and relative apical longitudinal strain index were associated with worsening LA strain after tafamidis administration. Our findings could represent an additional parameter for the effective management of patients with ATTR-CM.Figure AFigure B