Background:We sought to assess left atrial (LA) morphology and function in patients with transthyretin cardiac amyloidosis (TTR-CA) and hypertrophic cardiomyopathy (HCM). Primarily, longitudinal deformation (reservoir) and pump function were the focus of vector-velocity strain echocardiography imaging.

Methods and Results:The study group comprised 32 patients (mean age 57.7±15.4 years, 16 in each group), and 15 healthy controls. Diagnosis of TTR-CA was based on echocardiography and either gadolinium-enhanced (LGE) cardiac magnetic resonance (cMRI) or radionuclide imaging. At baseline, there were no differences in age, body surface area, blood pressure and risk factors among the groups. Left ventricular (LV) mass was greater in patients than in controls, and slight LA dilatation was found in the TTR-CA group. LA reservoir was 14.1±4.7% in TTR-CA, 20.0±5.6% in HCM, and 34.0±11.8% in controls (<0.001). In addition, LA pump function chiefly was impaired in the former group, irrespective of LA chamber size and LV ejection fraction. LGE in the atrial wall was seen in 9/10 TTR-CA versus 0/8 HCM patients undergoing cMRI (P<0.001). LA reservoir ≤19% and pump function ≤–1.1% best discriminated TTR-CA from HCM patients in the receiver-operating characteristic analysis.

Conclusions:LA reservoir and pump function were significantly impaired in both TTR-CA and HCM patients compared with controls, but mainly in the former group, irrespective of LA volume and LV ejection fraction, likely caused by a more altered LA wall structure. (Circ J 2016; 80: 1830–1837)