Relationship between changes in renal function after acute phase of tafamidis administration and left ventricular diastolic function at mid-term follow-up in transthyretin cardiac amyloidosis

Abstract

Abstract Background A large number of heart failure (HF) patients present with various degrees of renal dysfunction, known as cardio-renal syndrome. Renal impairment in HF patients is also associated with an independent risk factor for morbidity and mortality. Transthyretin (TTR) amyloidosis (ATTR) is characterized by disintegrated liver-derived TTR that accumulates as amyloid fibrils in the myocardium, leading to initially presenting as left ventricular (LV) hypertrophy and LV diastolic dysfunction. Although there is no proven therapy for patients with ATTR cardiomyopathy (ATTR-CM), tafamidis meglumine, a TTR stabilizer, has been associated with favorable outcomes. Although the kidneys are also an important organ where amyloid deposition occurs, the effect of tafamidis on renal function and its relationship to LV diastolic function is unclear. Purpose The purpose of this study was to investigate the relationship between changes in renal function after the acute phase of tafamidis administration and LV diastolic function at mid-term follow-up in patients with ATTR-CM. Methods We studied 56 patients with biopsy-proven ATTR-CM who were treated with tafamidis. All patients underwent blood examinations before and 45.6 ± 23.0 days after the acute phase of tafamidis administration. Echocardiography was performed before and 15.6 ± 9.8 months after the mid-term of tafamidis administration. The primary endpoint was defined as a composite of cardiovascular death or HF hospitalization for 5.0 years. Results Twelve patients had improved renal function as assessed by estimated glomerular filtration rate in the acute phase after tafamidis administration, while 44 patients deteriorated. In the group with improved renal function in the acute phase after tafamidis administration, pulsed-wave Doppler-derived early diastolic velocity from the septal mitral annulus (E’) and left atrial volume index (LAVI) tended to improve at mid-term follow-up compared to the non-improved group. (E’: 0.8 ± 1.7 cm/s vs. 0.2 ± 1.1 cm/s, p=0.127, LAVI: -8.7 ± 12.0 mL/m2 vs. 0.2 ± 16.8 mL/m2, p=0.093). Furthermore, Kaplan-Meier curve indicated that the occurrence of cardiovascular events for patients with improved renal function in the acute phase after tafamidis administration tended to be lower than those without (log-rank P=0.137). Conclusions The improvement of renal function in the acute phase after tafamidis administration was associated with the improvement of LV diastolic function at mid-term follow-up, leading to favorable outcome. Our findings may provide new insights for the management of patients with ATTR-CM.