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Incidence and Sequelae of Prosthesis-Patient Mismatch in Transcatheter Versus Surgical Valve Replacement in High-Risk Patients With Severe Aortic Stenosis: A PARTNER Trial Cohort-A Analysis
Study Questions:
What are the incidence and outcomes of patient-prosthesis mismatch (PPM) in patients treated with transcatheter aortic valve replacement (TAVR) and surgical aortic valve replacement (SAVR)?
Methods:
This study compared the incidence and outcomes of PPM in patients with severe symptomatic aortic stenosis (AS) randomized to a balloon-expandable TAVR (n = 304) or SAVR (n = 270). The study further evaluated the relationship between PPM and outcomes in 1,637 patients treated with TAVR as part of a separate registry. Moderate or severe (overall) PPM was defined by echocardiography as an indexed effective orifice area ≤0.85 cm2/m2; severe PPM was defined as a value <0.65 cm2/m2.
Results:
The incidence of overall PPM was 46.4% in those randomized to TAVR (19.7% severe) and 60.0% in patients randomized to SAVR (28.1% severe), with a significant difference between groups (p < 0.001). Overall, PPM remained different at 30 days (42% vs. 57% for TAVR and SAVR, respectively; p < 0.001). In registry patients treated with TAVR, the incidence of overall PPM was 43.8% (13.6% severe); there was no difference in PPM between those undergoing transfemoral versus transapical approach, or in patients with or without a valve-in-valve procedure; patients treated with post-dilation (vs. without) had reduced (p < 0.001) PPM (30.6% vs. 45.8% overall; 8.6% vs. 14.3% severe). Patients with an annulus diameter <20 mm had increased severe PPM in patients treated with SAVR as compared to TAVR (33.7% vs. 19.0%, p = 0.002). PPM was independently associated with reduced left ventricular mass regression at 1 year in those randomized to SAVR (p = 0.02), but not TAVR (p = 0.35); PPM in the TAVR registry was independently associated with decreased left ventricular mass regression (p = 0.01). After multivariable adjustment, patients randomized to SAVR with severe PPM had increased 2-year mortality (hazard ratio [HR], 1.78; p = 0.04), while there was no difference in those with any PPM (p = 0.09). In patients randomized to TAVR, the presence of any (p = 0.46) or severe PPM (p = 0.11) was not independently associated with mortality. In the TAVR registry, any PPM was not associated with 1-year mortality in the overall cohort, although in the subset with no or minimal aortic regurgitation (n = 835), severe PPM was independently associated with increased mortality (HR, 1.88; p = 0.02).
Conclusions:
The investigators concluded that PPM is more frequent and severe following SAVR. Severe PPM is associated with increased mortality after SAVR, while severe PPM following TAVR is associated with increased mortality only in the subgroup without significant aortic regurgitation.
Perspective:
This study finds that PPM, which occurs when the valve orifice is too small for body size, is relatively common with both TAVR and SAVR, although SAVR is associated with a significantly higher incidence of both moderate and severe PPM. The valve prosthesis of the TAVR device has a thinner profile than SAVR devices, as there is no need for a sewing ring, and this provides a larger orifice area, improving valve hemodynamics and reducing PPM. As may be expected, patients with a small annulus size were at a particularly high risk of PPM with SAVR, suggesting this group may have an increased benefit from TAVR. Consistent with existing data, severe PPM was associated with increased mortality after SAVR; the present findings suggest that severe PPM in TAVR patients without significant aortic regurgitation may also convey greater risk. As we try to better identify patients most and least likely to benefit from aortic valve procedures, we need to consider the risk of PPM.
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