Abstract Body (Do not enter title and authors here): Wild-type transthyretin amyloidosis (ATTR) is a potential one of the underlying causes of heart failure in the elderly, and in recent years, the complication rate with severe aortic stenosis (AS) has been reported to be higher than previously expected. We suspected cardiac amyloidosis (CA) in 142 of 824 patients referred for Severe AS between March 2020 and December 2023 and screened according to guidelines. Pathology was able to diagnose cardiac amyloidosis in 13 cases (1 immunoglobulin light chain, 11 ATTR, and 1 case of unknown type). Four cases were positive for technetium 99m pyrophosphate cardiac imaging and pathology could not be confirmed. Technetium 99m pyrophosphate cardiac imaging was negative in 125 cases. Of these, 115 patients (10 patients of ATTR-AS vs. 105 patients of Lone AS) who could be followed up after 6 months were compared. The median age of all patients was 85 years (interquartile range: 83 to 88) and 30.4% were male (60.0% vs. 27.6%; p=0.065). Pre-operative high-sensitivity troponin I values were higher in ATTR-AS group (58.2 [42.1 to 177.2] pg/mL vs. 20.2 [11.1-47.5] pg/mL; p=0.001), left ventricular ejection fraction tended to be lower (51.7 [41.7 to 58.8] % vs. 63.6 [54.3 to 69.3] %; p=0.015) and left ventricular mass index (LVMi) was significantly higher; no significant differences in AS severity were observed. Only one case of ATTR-AS was treated with surgical aortic valve replacement (AVR), while the other cases were treated with transcatheter AVR. Six months after AVR, there was no regression of LVMi and no statistically significant improvement in left ventricular diastolic and systolic performance in ATTR-AS group. Furthermore, New York Heart Association cardiac function classifications tended to have residual symptoms. The effect of therapeutic intervention on the aortic valve may be limited in ATTR-AS and is reported with a literature review.