Background:
In transcatheter aortic valve implantation (TAVI), borderline annular dimensions frequently necessitate off-label sizing. While intra-annular and supra-annular valves possess distinct biomechanical profiles, their hemodynamic performance when implanted marginally outside manufacturer-recommended area instructions for use (IFU) remains poorly characterized. This study investigates the post-interventional hemodynamics and paravalvular leak (PVL) of Sapien and Evolut valves in these sizing extremes.
Methods:
A retrospective analysis of 950 patients that received TAVI between 2022 and 2024 compared post-procedural mean gradients (dPmean) and PVL across the complete spectrum of Evolut (E23, E26, E29, E34) and Sapien (S23, S26, S29) sizes. Groups were stratified by implantation strictly within standard IFU limits versus implantation outside the IFU; the latter accounted for 7% of all implantations.
Results:
Supra-annular valves were frequently implanted in smaller-than-recommended annuli without hemodynamic penalty or significant increases in PVL across all observed sizes. For constrained E26 (n=8) vs. standard (n=43), dPmean was 7.25 vs. 7.38 mmHg (p=0.91; PVL p=0.45). Similar non-significant differences were observed for E29 (dPmean 7.33 vs. 7.24 mmHg, p=0.86) and E34 (dPmean 6.86 vs. 6.67 mmHg, p=0.71), with stable PVL. (Implantation of E23 in larger annuli did not occur in this cohort).
Conversely, oversized intra-annular valves (larger valve in smaller annulus) were actively avoided, resulting in small cohorts (S29 n=3; S26 n=9) that exhibited non-significant trends towards higher dPmean due to constrained expansion. However, when placed in marginally larger annuli, intra-annular valves demonstrated significantly improved hemodynamics. The S26 in larger annuli (observed maximum <25 mm² above IFU, n=16) showed lower dPmean compared to the standard range (n=34) (8.88 vs. 12.28 mmHg, p=0.018) with stable PVL (p=0.62). Similarly, the S23 in larger annuli (n=6) demonstrated lower dPmean versus standard (n=9) (11.00 vs. 16.22 mmHg, p=0.040) without increased PVL.
Conclusion:
In minor sizing discrepancies, fundamental valve mechanics dictate hemodynamics. Supra-annular valves maintain excellent flow profiles when constrained in smaller annuli. Intra-annular balloon-expandable valves suffer when constrained but exhibit superior hemodynamics when placed in slightly oversized annuli. The natural clinical limitation of this oversizing (observed at <25 mm² above IFU) allows for unconstrained maximal frame expansion without compromising paravalvular sealing.
