Routine 4D Cardiac Computed Tomography to Identify Concomitant Transthyretin Amyloid Cardiomyopathy in TAVI candidates with Severe Aortic Stenosis

Abstract

Funding Acknowledgements Type of funding sources: Other. Main funding source(s): Bangerter-Rhyner Foundation, Pfizer, GAMBIT foundation. Background Transthyretin amyloid cardiomyopathy (ATTR-CM) may coexist in patients with severe aortic stenosis (AS) considered for transcatheter aortic valve implantation (TAVI). The diagnosis of ATTR-CM by 99mTechnetium-3,3-diphosphono-1,2-propanodicarboxylic-acid (DPD)-scintigraphy is costly, whereas endomyocardial biopsy is associated with relevant procedural risks and sampling error. Objectives To evaluate whether ATTR-CM may be diagnosed by routine 4D cardiac computed tomography (4DCCT). Methods In a prospective screening study for ATTR-CM, the diagnostic performance of 4DCCT-based left- (LV), right ventricular (RV) and left atrial (LA) dimensions, ejection fraction (EF) and myocardial strain was evaluated against DPD-scintigraphy to identify ATTR-CM. Diagnostic predictors and a newly developed 4DCCT-score were validated by internal bootstrapping. Results Among 263 patients considered for TAVI (57% males,age 83±4.6 years) undergoing 4DCCT, DPD-scintigraphy (Perugini grade 2–3) confirmed co-existing ATTR-CM in 27 (10.3%) patients. Patients with ATTR-CM had impaired 4DCCT-based LVEF, LV global longitudinal strain (GLS), and LA-GLS. LV mass index, LV-GLS, LA-GLS and relative apical longitudinal strain (ratio of apical to basal/midventricular strain), each predicted the presence of ATTR-CM with an area under the curve (AUC) of >0.7. Implementing these parameters with cutoff-values of ≥81g/m2, ≥-14.9%, <11.5% and ≥1.7 in an unweighted score yielded high prognostic accuracy (AUC=0.89; 95%CI:0.81–0.94;p<0.001), robust to internal bootstrapping validation (AUC=0.88;95%CI:0.82–0.94). If two criteria were fulfilled, sensitivity and specificity to detect ATTR-CM were 96.3 and 58.9%, respectively. Conclusions Clinically indicated, routine 4DCCT in patients considered for TAVI provides high diagnostic yield to detect concomitant ATTR-CM, by assessing LV- and LA-GLS, LV relative apical longitudinal strain and LV mass index.