Impact of Prosthesis-Patient Mismatch on Long-term Functional Capacity After Mechanical Aortic Valve Replacement

Intermediate Follow-Up of Balloon-Expandable Versus Self-Expanding Transcatheter Aortic Valve Implantation in Patients With Small Aortic Annuli

The clinical impact of prosthesis-patient mismatch (PPM) in patients with small aortic annuli who underwent transcatheter aortic valve (AV) implantation with either balloon-expandable (BE) or self-expanding (SE) valves remains controversial. We assessed in-hospital and intermediate clinical outcomes in 573 patients with transfemoral transcatheter AV implantation with a small AV annulus, defined as an AV annulus area ≤430 mm². A total of 337 patients treated with a 23-mm BE valve (SAPIEN 3, Ultra) were compared with 236 patients treated with a 26-mm SE valve (Evolut series). Valve-in-valve cases were excluded, and late echo follow-up (mean 674 ± 438 days) was assessed in a subset of 292 patients (51.0%). Well-matched BE and SE cohorts did not differ with respect to major in-hospital outcomes, other than a borderline increase in vascular complications and composite bleeding in patients with SE. Patients with BE had a higher incidence of severe PPM on discharge echocardiography (16.9% vs 6.8%, p <0.002). The mean AV gradient at 30 days was higher for patients with BE (12.2 ± 4.2 vs 6.2 ± 7.9 mm Hg, p <0.001) and at late follow-up (14.0 ± 8.2 vs 7.2 ± 3.5 mm Hg, p <0.001). The follow-up left ventricular ejection fraction and incidence of >mild aortic insufficiency were similar. All-cause mortality for the 2 cohorts was similar, with an overall mean (95% confidence interval) survival time of 61.2 months (57.8 to 64.5; p = 0.98). There were no significant survival differences between combined patients with BE and SE with no, moderate, or severe PPM, with an overall mean (95% confidence interval) survival time of 32.5 (30.5 to 34.5) months combining valve types (p = 0.23). In conclusion, despite an increased incidence of PPM with higher mean AV gradients that persist on late echocardiography in the BE cohort, patients with BE and SE with small aortic annuli have similar clinical outcomes at intermediate follow-up. Moderate and severe PPM had no impact on survival at a mean follow-up of 32.5 months.

Patient Prosthesis Mismatch After SAVR and TAVR

Patient-prosthesis mismatch (PPM) remains one out of many factors to be considered during decision-making for the treatment of aortic valve pathologies. The idea of adequate sizing of a prosthetic heart valve was established by Rahimtoola already in 1978. In this article, the author described the phenomenon that the orifice area of a prosthetic heart valve may be too small for the individual patient. PPM is assessed by measurement or projection of the prosthetic effective orifice area indexed to body surface area (iEOA), while it is recommended to use different cut point values for non-obese and obese patients for the categorization of moderate and severe PPM. Several factors influence the accuracy of both the projected and the measured iEOA for PPM assessment, which leads to a certain number of false assignments to the PPM or no PPM group. Despite divergent findings on the impact of PPM on clinical outcomes, there is consensus that PPM should be avoided to prevent sequelae of increased prosthetic gradients after aortic valve replacement. To prevent PPM, it is required to anticipate the iEOA of the prosthesis prior to the procedure. The use of adequate reference tables, derived from echocardiographically measured mean effective orifice area (EOA) values from preferably large numbers of patients, is most appropriate to predict the iEOA. Such tables should be used also for transcatheter heart valves in the future. During the decision-making process, all available options should be taken into account for the individual patient. If the predicted size and type of a surgical prosthesis cannot be implanted, additional surgical procedures, such as annular enlargement with the Manougian technique, or alternative procedures, such as transcatheter aortic valve implantation (TAVI) can prevent PPM. PPM prevention for TAVI patients is a new field of interest and includes anticipation of the iEOA, prosthesis selection, and procedural strategies.

Patient–Prosthesis Mismatch in Contemporary Small-Size Mechanical Prostheses Does Not Impact Survival at 10 Years

Background: The effect of PPM in mechanical prostheses on long-term survival is not well-established. Methods: Patients who received a 21 mm or smaller aortic valve between 2000 and 2011 were retrospectively analyzed (n = 416). Propensity matching was used in order to account for baseline differences in patient subgroups (PPM vs. no PPM; severe PPM vs. no severe PPM). Results: Five- and ten-year survival was 78 ± 3.52% and 64.51 ± 4.51% in patients with PPM, versus 83.3 ± 3.12% and 69.37 ± 4.36% in patients without (p = 0.28) when analyzed at 10.39 ± 5.25 years after the primary procedure. Independent risk factors for impaired survival, after matching, were age, serum creatinine, and severe pulmonary hypertension. Five- and ten-year survival in patients with severe PPM was 73.34 ± 6.01% and 61.76 ± 8.17%, respectively, versus 74.72 ± 5.68% and 67.50 ± 7.09% in those without (p = 0.49), at 8.82 ± 5.17 years after SAVR. Age was the only independent variable that influenced long-term survival when severe PPM was added to the model. Conclusions: PPM or severe PPM does not impact long-term survival up to 10 years in mechanical valve recipients when matching for preoperative variables.

Patient-prosthesis mismatch and surgical aortic valve replacement outcomes: Retrospective analysis of single-center surgical data

BACKGROUND

Patient-prosthesis mismatch (PPM) has been identified as a risk factor for mortality and reoperation in patients undergoing surgical aortic valve replacement (SAVR). We present a retrospective analysis of risk factors for PPM and the effects of PPM on early postoperative outcomes after SAVR.

METHODS

Chart review was conducted for patients (N = 3003) undergoing SAVR. PPM was calculated from valve reference orifice areas and patient body surface area. Logistic regression was used to analyze risk factors for PPM and develop a risk score from these results. Regression was also conducted to identify associations between projected PPM status and postoperative outcomes.

RESULTS

Risk factors for PPM included female sex, higher body mass index (BMI), and use of the St. Jude Epic valve. Patients receiving St. Jude trifecta valves or mechanical valves were less likely to have predicted PPM. We developed a risk score using BMI, sex, and valve type, and retrospectively predicted PPM in our cohort. Mild PPM (odds ratio [OR] = 2.267), severe PPM (OR = 2.869), male sex (OR = 2.091), and younger age (OR = 0.940) were all predictors of SAVR reoperation, while aortic root replacement was associated with reduced reoperation rates (OR = 0.122). Severe PPM carried a risk of in-hospital mortality (OR = 3.599), and moderate PPM carried a smaller but significant risk (OR = 1.920). Other factors increasing postoperative morbidity and mortality included older age, renal failure, and diabetes.

CONCLUSION

PPM could be retrospectively predicted in our cohort using a risk calculation from sex, BMI and valve type. We conclude that all degrees of PPM carry risk for mortality and reoperation.

Development and characterisation of cytocompatible polyester substrates with tunable mechanical properties and degradation rate

Although it has been repeatedly indicated the importance to develop implantable devices and cell culture substrates with tissue-specific rigidity, current commercially available products, in particular cell culture substrates, have rigidity values well above most tissues in the body. Herein, six resorbable polyester films were fabricated using compression moulding with a thermal presser into films with tailored stiffness by appropriately selecting the ratio of their building up monomers (e.g. lactide, glycolide, trimethylene carbonate, dioxanone, ε-caprolactone). Typical NMR and FTIR spectra were obtained, suggesting that the fabrication process did not have a negative effect on the conformation of the polymers. Surface roughness analysis revealed no apparent differences between the films as a function of polymer composition. Subject to polymer composition, polymeric films were obtained with glass transition temperatures from -52 °C to 61 °C; contact angles in water from 81 ° to 94 °; storage modulus from 108 MPa to 2,756 MPa and loss modulus from 8 MPa to 507 MPa (both in wet state, at 1 Hz frequency and at 37 °C); ultimate tensile strength from 8 MPa to 62 MPa, toughness from 23 MJ/m³ to 287 MJ/m³, strain at break from 3 % to 278 %, macro-scale Young's modulus from 110 MPa to 2,184 MPa (all in wet state); and nano-scale Young's modulus from 6 kPa to 15,019 kPa (in wet state). With respect to in vitro degradation in phosphate buffered saline at 37 °C, some polymeric films [e.g. poly(glycolide-lactide) 30 / 70] started degrading from day 7 (shortest timepoint assessed), whilst others [e.g. poly(glycolide-co-ε-caprolactone) 10 / 90] were more resilient to degradation up to day 21 (longest timepoint assessed). In vitro biological analysis using human dermal fibroblasts and a human monocyte cell line (THP-1) showed the potential of the polymeric films to support cell growth and controlled immune response. Evidently, the selected polymers exhibited properties suitable for a range of clinical indications.

[Clinical results of cardiac valve repair with bicuspid full-flow mechanical prosthesis 'MedEng-ST']

Prosthetic repair of cardiac valves with artificial mechanical prostheses is ubiquitously performed using prostheses consisting of two cusps (bicuspidal). Several years ago, new bicuspid full-flow prostheses appeared on the market. From the first use they immediately proved reliable, with stable haemodynamic characteristics. At the Interregional Clinical and Diagnostic Centre, bicuspid full-flow mechanical prostheses 'MedEng-ST' have been used since 2017. We carried out a retrospective follow up of 84 patients subjected to prosthetic repair of cardiac valves with full-flow prostheses 'MedEng-ST' in mitral and aortic positions. There were no prosthesis-associated or procedural complications during follow up. Neither were there major complications in the postoperative period. All complications were related to peculiarities of the approach to the heart. We assessed the functional parameters of the heart by standard echocardiography. The obtained findings demonstrated good haemodynamic parameters on the 'MedEng-ST' prostheses, improved intracardiac haemodynamics, which eventually had a beneficial effect on the patients' clinical picture. The transprosthetic gradients had stable parameters with a decrease in time when placing the 'MedEng-ST' prosthesis into the aortic position (p≤0.05). Proceeding from the obtained results, as well as taking into account the absence of thromboembolic events it may be stated that the proposed design of the device is universal for replacement of the aortic and mitral valves of the heart. Based on the obtained findings of the study we recommend to use the 'MedEng'ST' prostheses in clinical practice. Further studies are required for more convincing data and explicit recommendations.