Prognostic impact of echocardiographic mean transvalvular gradients in patients with aortic stenosis and low flow undergoing transcatheter aortic valve implantation

Background: Blunted left ventricular hemodynamics reflected by a low stroke volume index (SVI) ≤35 mL/m² body surface area (low flow [LF]) in patients with severe aortic stenosis (AS) are associated with worse outcomes even after correction of afterload by transcatheter aortic valve implantation (TAVI). These patients can have a low or high transvalvular mean pressure gradient (MPG). We investigated the impact of the pre-interventional MPG on outcomes after TAVI.

Methods: Patients with LF AS were classified into those with normal (EF ≥ 50%; LF/NEF) or reduced ejection fraction (EF < 50%; LF/REF) and were then stratified according to an MPG < or ≥ 40 mmHg. Patients with SVI >35 mL/m² (normal flow; NF) served as controls.

Results: 597 patients with LF/NEF, 264 patients with LF/REF and 975 patients with NF were identified. Among all groups those patients with a low MPG were characterized by higher cardiovascular risk. In patients with LF/REF, functional improvement post-TAVI was less pronounced in low-MPG patients. One-year survival was significantly worse in LF AS patients with a low vs. high MPG (LF/NEF 16.5% vs. 10.5%, p = 0.022; LF/REF 25.4% vs. 8.0%, p = 0.002), whereas no differences were found in NF patients (8.7% vs. 10.0%, p = 0.550). In both LF AS groups, a low pre-procedural MPG emerged as an independent predictor of mortality.

Conclusions: In patients with LF AS, an MPG cut-off of 40 mmHg defines two patient populations with fundamental differences in outcomes after TAVI. Patients with LF AS and a high MPG have the same favorable prognosis as patients with NF AS.