Background: Several studies have recently reported that transthyretin (ATTR) amyloidosis is present in patients with aortic stenosis (AS). We aimed to 1) examine the prevalence of ATTR amyloidosis in AS patients undergoing transcatheter aortic valve implantation (TAVI), 2) compare clinical characteristics between AS patients with and without ATTR, and 3) identify predictors of ATTR amyloidosis in AS patients. Methods and Results: We prospectively analyzed consecutive 32 patients with severe AS who underwent screening tests for ATTR in prior to TAVI. To detect ATTR, we performed cardiac technetium-99m pyrophosphate ( 99m Tc-PYP) scintigraphy in 24 patients and biopsies of fat tissue from the puncture site in 24 patients. Of 32 AS patients who were screened for ATTR, 6 (18.8%) patients were diagnosed as ATTR by cardiac 99m Tc-PYP scintigraphy (n=2) and fat biopsy (n=5). Compared with non-ATTR patients, ATTR patients presented higher levels of B-type natriuretic peptide (BNP, 242.3 vs. 1101.4 ng/ml, P=0.004), lower left ventricular ejection fraction (LVEF, 62.3 vs. 45.5%, P=0.002) and lower mean pressure gradient of AS (50.2 vs. 32.0 mmHg, P=0.016). In contrast, age, sex, STS score, clinical frailty scale, prevalence of chronic kidney disease and atrial fibrillation, and levels of hemoglobin, albumin, estimated glomerular filtration rate and troponin I were comparable between the two groups. Other echocardiographic parameters including interventricular septal wall thickness, posterior wall thickness and aortic valve area did not differ between the two groups. To detect ATTR among AS patients, receiver operating characteristic (ROC) analysis demonstrated that area under the curve of BNP, LVEF, and mean pressure gradient was 0.814, 0.766 and 0.846, respectively. Although TAVI was successfully completed in all patients, and there was no procedural complication in both groups, one of ATTR patients re-hospitalized due to decompensated heart failure 3 weeks after TAVI. Conclusion: In AS patients undergoing TAVI, especially in cases of low-flow low-gradient pattern and high BNP levels, screening of ATTR should be considered. In this population, cardiac 99m Tc-PYP scintigraphy and fat biopsy are useful to detect latent ATTR non-invasively.
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