Prosthesis-patient mismatch (PPM) occurs when the effective orifice area (EOA) after valve placement is significantly smaller compared with the patient’s body surface area (BSA), resulting in an increased transprosthetic residual gradient. The presence of PPM, especially in various surgical series, has been associated with long-term adverse clinical events.
In relation to transcatheter aortic valve implantation (TAVI), there is a variation in the detection of PPM in terms of its diagnosis between early studies (which relied solely on echocardiographic measurements) and more recent studies. This suggests that the most accurate way to measure it would be through a predicted measurement, based on the EOA according to the manufacturer’s specifications in relation to the patient’s body surface area and the annular diameter, measured by computed tomography (CT).
While the presence, frequency, and follow-up of PPM in TAVI are limited, the aim of this study was to systematically assess long-term clinical events in a prospective cohort that included different valve types and generations, and assessed PPM using various methods.
Researchers used the Bern TAVI Registry in Switzerland, which included consecutive patients with symptomatic severe aortic stenosis. The registry included patients with balloon-expandable valves (SAPIEN XT, SAPIEN 3, SAPIEN 3 Ultra) or self-expandable valves (CoreValve, Evolut R/PRO/Pro Plus), between August 2007 and June 2022.
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PPM was classified based on the EOA indexed to body surface area into three categories: trivial (>0.85 cm2/m2), moderate (EOAi >0.65 to ≤0.85 cm2/m2), or severe (EOAi ≤0.65 cm2/m2), with different cutoff thresholds for the obese population.
The study collected data from 2463 patients, including PPM measurements using echocardiography (EOA indexed, EOAi) and predicted PPM (according to the manufacturer [EOATHV] or defined by CT [EOATC]). Overall, 46.9% of the patients were women, and the average age was 82 ± 6 years. The average STS score was 5 ± 3.9%, and 22.8% of patients were obese. The transfemoral approach was the most frequently used, accounting for 93.6% of cases.
The frequency of moderate and severe PPM varied depending on the different measurement methods. Using EOAi, 27% of patients had moderate PPM and 8.7% had severe PPM. In contrast, using EOATHV, the figures were 11.3% and 1.2%, respectively, and using EOATC, they were 12% and 0.1%, respectively. Furthermore, severity was lower in the obese population compared with the non-obese population.
Regarding valve type, balloon-expandable valves showed a higher frequency of moderate to severe PPM, while EOATHV indicated severity only in self-expandable valves.
Patients with moderate to severe PPM, defined by any method, had higher average gradients and a higher prevalence of elevated residual gradients (p <0.001). There were no significant differences regarding the paravalvular regurgitation index.
The average follow-up time was 429 days. One-year all-cause mortality was 10.5%, 5-year mortality was 52.8%, and 10-year mortality was 84.3% in the trivial PPM group. On the other hand, in the moderate PPM group, one-year mortality was 12.2%, 5-year mortality was 58.3%, and 10-year mortality was 89.7%. Cardiovascular mortality at 10 years was higher in patients in the EOAi group, although the rates of valve deterioration and reintervention were similar across all evaluated groups. When analyzing survival, there was no significant increase in the risk of mortality associated with PPM, regardless of the method used.
Conclusions
The results suggest that predicted EOA provides a less severe assessment of PPM compared with EOAi measured by conventional echocardiography in patients undergoing TAVI. However, this difference does not seem to have a significant impact on 10-year mortality, although it is important to note that the average follow-up of 429 days limits the ability to draw definitive conclusions.
Dr. Omar Tupayachi.
Member of the Editorial Board of SOLACI.org.
Reference: Tomii, Daijiro et al. “Long-term outcomes of measured and predicted prosthesis-patient mismatch following transcatheter aortic valve replacement.” EuroIntervention : journal of EuroPCR in collaboration with the Working Group on Interventional Cardiology of the European Society of Cardiology, EIJ-D-23-00456. 25 Aug. 2023, doi:10.4244/EIJ-D-23-00456.
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