Clinical Impact of Midframe Underexpansion Following TAVR Using a Self-Expanding Transcatheter Heart Valve

Background: The occurrence and clinical impact of transcatheter heart valve midframe underexpansion following transcatheter aortic valve replacement are not well understood. Objectives: The aim of this study was to evaluate midframe underexpansion among patients treated with the self-expanding ACURATE neo2 device. Methods: This retrospective analysis included 604 patients (median age 82 years; Q1-Q3: 78-85 years; 61.4% women) from 2 European high-volume centers. Midframe underexpansion was assessed on postimplantation fluoroscopic images and defined as nonparallelism of commissure posts. The primary endpoint was a composite of all-cause mortality, stroke, or rehospitalization at 1 year. Results: Midframe underexpansion was identified in 13.9% of patients (84 of 604) and was associated with higher rates of the primary endpoint (33 of 84 [39.3%; 95% CI: 28.8%-50.5%] vs 54 of 520 [10.4%; 95% CI: 7.9%-13.3%]; P < 0.001) and each of its components. Furthermore, midframe underexpansion was independently associated with 1-year all-cause mortality (adjusted HR: 4.07; 95% CI: 2.26-7.33; P < 0.001). The only independent predictor of midframe underexpansion was the absence of postdilatation (adjusted OR: 5.76; 95% CI: 2.60-12.77; P < 0.001). Postdilatation significantly decreased the rate and extent of midframe underexpansion. Conclusions: In this European cohort of ACURATE neo2 recipients, midframe underexpansion occurred in a minor proportion and was associated with poorer clinical outcomes through 1 year. Postdilatation effectively reduced the rate and extent of midframe underexpansion.