Change in echocardiography in patients with transthyretin amyloid cardiomyopathy with tafamidis treatment
Authors: Morioka M , Takashio S , Fujiyama H , Oike F , Hanatani S , Usuku H , Yamamoto E , Matsushita K , Tsujita K 
Published: October 2022

Abstract

Background
Transthyretin amyloid cardiomyopathy (ATTR-CM) is a progressive and infiltrative disease caused by the deposition of insoluble transthyretin (TTR) amyloid fibrils in the myocardium, which leads to cardiomyopathy characterized by increased ventricular wall thickness and diastolic dysfunction. TTR amyloid fibrils are performed by dissociation of the tetrameric TTR into monomers and misfolding and misassemble into insoluble fibrils. Tafamidis stabilizes the tetramers and inhibits the TTR monomerization, leads to inhibit the formation and deposition of TTR fibril. Clinical trials suggested tafamidis could improve prognosis by slowing the progression of amyloidosis. Evaluation of serial measurement echocardiographic findings by tafamidis treatment is important, but these data has not been fully revealed.

Purpose
The aim of study was to evaluate the change of echocardiographic parameter in patients with ATTR-CM received tafamidis for 12 months. Especially in strain echocardiogram, global longitudinal strain (GLS) has reported to be associated with prognosis, and apical sparing pattern, which longitudinal strain (LS) in the basal and middle segments is more severely impaired than the apical segments, is specific finding in ATTR-CM.

Method
Echocardiographic findings before and 12 months were compared in 68 patients with ATTR-CM who started a new prescription of tafamidis and 18 tafamidis naïve patients with ATTR-CM patients who underwent echocardiography annually prior to the approval of tafamidis.

Result
Among tafamidis treatment group, echocardiographic parameters were not significant changes before and after 12 months tafamidis treatment [left ventricular ejection fraction (LVEF): 49.6±10.6% vs. LVEF: 49.9±10.7% (p=0.767), interventricular septum diameter (IVSd):16.0±2.3mm vs 15.7±2.1mm (p=0.241), left ventricular posterior wall diameter (LVPWd):16.1±2.5mm vs 16.1±2.5mm (p=0.964), GLS: −8.4±2.7% vs −8.2±2.8% (p=0.419), LS at base: −4.6±2.6% vs −4.2±2.4% (p=0.291), LS at middle: −6.9±3.6% vs −6.9±2.8% (p=0.922), LS at apical:-12.7±4.2% vs −12.4±4.4% (p=0.615). Among tafamidis naïve group, these parameters remained almost unchanged in 12 months as well, except for GLS and LS at apical. LS at apical showed a significant impairment. [LVEF: 53.8±9.2% vs 51.7±9.3% (p=0.244), IVSd: 15.5±2.3mm vs 16.0±1.8mm (p=0.321), LVPWd: 15.4±2.3mm vs 15.9±2.3mm (p=0.267), GLS: −10.4±2.4% vs −9.0±2.9% (p=0.065), LS at base: −5.0±2.7% vs −5.1±2.9% (p=0.865), LS at middle: −8.9±3.1% vs −8.5±3.5% (p=0.565), LS at apical: −15.4±4.0% vs −12.6±4.4% (p=0.02); Table 1]

Conclusion
We evaluated changes in echocardiographic findings with tafamidis treatment for 12 months. The echocardiographic parameters did not change over the course of 12 months, but the decrease in LS at apex observed in the tafamidis naïve group.Segmental LS could reflect a slight progression of cardiac amyloidosis and the short-term effects of tafamidis.

Funding Acknowledgement
Type of funding sources: None.