Prognosis After Aortic Valve Replacement With the Carpentier-Edwards Pericardial Valve: Use of Microsimulation

Paediatric aortic valve replacement: a meta-analysis and microsimulation study

AIMS

To support decision-making in children undergoing aortic valve replacement (AVR), by providing a comprehensive overview of published outcomes after paediatric AVR, and microsimulation-based age-specific estimates of outcome with different valve substitutes.

METHODS AND RESULTS

A systematic review of published literature reporting clinical outcome after paediatric AVR (mean age <18 years) published between 1/1/1990 and 11/08/2021 was conducted. Publications reporting outcome after paediatric Ross procedure, mechanical AVR (mAVR), homograft AVR (hAVR), and/or bioprosthetic AVR were considered for inclusion. Early risks (<30d), late event rates (>30d) and time-to-event data were pooled and entered into a microsimulation model. Sixty-eight studies, of which one prospective and 67 retrospective cohort studies, were included, encompassing a total of 5259 patients (37 435 patient-years; median follow-up: 5.9 years; range 1-21 years). Pooled mean age for the Ross procedure, mAVR, and hAVR was 9.2 ± 5.6, 13.0 ± 3.4, and 8.4 ± 5.4 years, respectively. Pooled early mortality for the Ross procedure, mAVR, and hAVR was 3.7% (95% CI, 3.0%-4.7%), 7.0% (5.1%-9.6%), and 10.6% (6.6%-17.0%), respectively, and late mortality rate was 0.5%/year (0.4%-0.7%/year), 1.0%/year (0.6%-1.5%/year), and 1.4%/year (0.8%-2.5%/year), respectively. Microsimulation-based mean life-expectancy in the first 20 years was 18.9 years (18.6-19.1 years) after Ross (relative life-expectancy: 94.8%) and 17.0 years (16.5-17.6 years) after mAVR (relative life-expectancy: 86.3%). Microsimulation-based 20-year risk of aortic valve reintervention was 42.0% (95% CI: 39.6%-44.6%) after Ross and 17.8% (95% CI: 17.0%-19.4%) after mAVR.

CONCLUSION

Results of paediatric AVR are currently suboptimal with substantial mortality especially in the very young with considerable reintervention hazards for all valve substitutes, but the Ross procedure provides a survival benefit over mAVR. Pros and cons of substitutes should be carefully weighed during paediatric valve selection.

Impact of Transcatheter Aortic Valve Durability on Life Expectancy in Low-Risk Patients With Severe Aortic Stenosis

Background:

Recent clinical trial results showed that transcatheter aortic valve replacement (TAVR) is noninferior and may be superior to surgical aortic valve replacement (SAVR) for mortality, stroke, and rehospitalization. However, the impact of transcatheter valve durability remains uncertain.

Methods:

Discrete event simulation was used to model hypothetical scenarios of TAVR versus SAVR durability in which TAVR failure times were varied to determine the impact of TAVR valve durability on life expectancy in a cohort of low-risk patients similar to those in recent trials. Discrete event simulation modeling was used to estimate the tradeoff between a less invasive procedure with unknown valve durability (TAVR) and that of a more invasive procedure with known durability (SAVR). Standardized differences were calculated, and a difference >0.10 was considered clinically significant. In the base-case analysis, patients with structural valve deterioration requiring reoperation were assumed to undergo a valve-in-valve TAVR procedure. A sensitivity analysis was conducted to determine the impact of TAVR valve durability on life expectancy in younger age groups (40, 50, and 60 years).

Results:

Our cohort consisted of patients with aortic stenosis at low surgical risk with a mean age of 73.4±5.9 years. In the base-case scenario, the standardized difference in life expectancy was <0.10 between TAVR and SAVR until transcatheter valve prosthesis failure time was 70% shorter than that of surgical prostheses. At a transcatheter valve failure time <30% compared with surgical valves, SAVR was the preferred option. In younger patients, life expectancy was reduced when TAVR durability was 30%, 40%, and 50% shorter than that of surgical valves in 40-, 50-, and 60-year-old patients, respectively.

Conclusions:

According to our simulation models, the durability of TAVR valves must be 70% shorter than that of surgical valves to result in reduced life expectancy in patients with demographics similar to those of recent trials. However, in younger patients, this threshold for TAVR valve durability was substantially higher. These findings suggest that durability concerns should not influence the initial treatment decision concerning TAVR versus SAVR in older low-risk patients on the basis of current evidence supporting TAVR valve durability. However, in younger low-risk patients, valve durability must be weighed against other patient factors such as life expectancy.

Aggressive tissue aortic valve replacement in younger patients and the risk of re-replacement: Implications from microsimulation analysis

OBJECTIVE

Advances in transcatheter aortic valve replacement have led to the consideration of tissue aortic valve replacement in younger patients. Part of this enthusiasm is the presumption that younger patients would have more flexibility in future treatment options, such as a primary surgical aortic valve replacement followed later by transcatheter aortic valve replacement(s) (valve-in-valve), vice versa, or other permutations. We created a microsimulation model using published longevity of tissue valves to predict the outcomes of patients after primary tissue surgical aortic valve replacement.

METHODS

The model calculated survival by incorporating annual mortality (Social Security Administration) and mortality from re-replacements (Society of Thoracic Surgeons) in patients with surgical aortic valve replacement. Freedom from reoperation for structural valve degeneration incorporated best published data to determine the annual risk of re-replacement for structural valve degeneration based on implant duration and stratified by patient age. A constant rate of re-replacement for nonstructural valve degeneration indications was also incorporated. Each simulation was performed for 50,000 individuals. Kaplan-Meier curves were generated to represent survival. All simulations were run within the MATLAB environment (The MathWorks, Inc, Natick, Mass).

RESULTS

Earlier decades of life at primary surgical aortic valve replacement were associated with higher incidences of re-replacements and especially multiple re-replacements. For those patients receiving a primary tissue surgical aortic valve replacement at age 50 years, 57.2% will require a second valve, 18.0% will require a third valve, and 1.6% will require a fourth valve with average operative mortalities of 2.9%, 4.8%, and 7.3%, respectively. A 50-year-old patient at primary surgical aortic valve replacement has a 13.1% chance of re-replacement before turning 60 years of age.

CONCLUSIONS

Microsimulation incorporates changing hazards to estimate the risk of aortic valve re-replacement in patients undergoing tissue surgical aortic valve replacement and may be a starting point for patient education and health care economic planning.

Choice of prosthetic heart valve in a developing country

Mechanical prostheses and stented xenografts (bioprosthesis) are most commonly used substitutes for aortic and mitral valve replacement. The mechanical valves have the advantage of durability but are accompanied with the risk of thromboembolism, problems of long-term anticoagulation, and associated risk of bleeding. In contrast, bioprosthetic valves do not require long-term anticoagulation, but carry the risk of structural valve degeneration and re-operation. A mechanical valve is favoured in young patients (<40 years) if reliable anticoagulation is ensured. In elderly patients (>60 years), a bioprosthesis is a suitable substitute. In middle-aged patients (40-60 years), risk of re-operation in a bioprosthesis is equal to that of bleeding in a mechanical valve. Traditionally, a bioprosthesis is opted in patients with limited life expectancy. Calculation of life expectancy, based solely upon chronological age, is erroneous. In developing countries, the calculated life expectancy is much lower than that of Western population, hence age related Western cut-offs are not valid in developing countries. Besides age, cardiac condition of the patient, systemic illnesses, socio-economic status, gender and geographical location also decide the life expectancy of the patients. Selection of the prosthetic valve substitute should be based on: aspiration of the patient, life expectancy, socio-economic and educational background, occupation of the patient, availability, cost, monitoring of anti-coagulation, monitoring of valve function and other valve related complications, and possibility of re-operation.

EFFICACY OF CARPENTIER-EDWARDS PERICARDIAL PROSTHESES: A SYSTEMATIC REVIEW AND META-ANALYSIS

Objectives: The Carpentier-Edwards pericardial (CEP) prostheses are the type of bioprostheses most used worldwide. Although they were designed to minimize the rate of valve deterioration and reoperation, their clinical superiority over other prostheses models still lacks confirmation. The objective of this study was to evaluate its effectiveness.

Methods: We performed a systematic review and meta-analysis in the PubMed, Embase, Cochrane, and Lilacs databases. Operative mortality, overall mortality and reoperation rates after heart valve surgery were compared between the use of CEP and other cardiac prostheses. Two independent reviewers screened studies for inclusion and extracted the data. Disagreements were resolved by consensus. The GRADE criterion was used to assess the evidence quality.

Results: A total of twenty-eight studies were selected, including 19,615 individuals. The studies presented a high heterogeneity and low quality of evidence what limited the reliability of the results. The pooled data from the selected studies did not demonstrate significant differences between CEP and porcine, pericardial or stentless prostheses regarding operative mortality, overall mortality and reoperation rates. However, the pooled data from 3 observational trials pointed out a higher risk for reoperation after valve replacement using CEP prostheses against mechanical prostheses (OR 4.92 [95 percent confidence interval 2.43–9.96]).

Conclusions: The current data present in the literature still does not support a clinical advantage for the use of CEP prostheses over other bioprostheses. The quality of the studies in the literature is limited and further studies are needed to address if CEP prostheses will have a clinical advantage over other prostheses.

Influence of the characteristics of Japanese patients on the long-term outcomes after aortic valve replacement: results of a microsimulation

Objectives

The aim of this study was to explore the influence of the characteristics of Japanese patients on the long-term outcomes after aortic valve replacement with either mechanical or biological prostheses by means of a microsimulation.

Methods

A microsimulation model was used to simulate the lives of patients living in Japan and in the United States after aortic valve replacement. The background mortality data taken from the 21st complete life table of Japan and the bleeding hazard determined from a meta-analysis of long-term results in Japanese institutions were used to simulate Japanese patients. The life expectancy, event-free life expectancy, and lifetime risk of structural valve degeneration were calculated. A sensitivity analysis for various bleeding hazards was performed.

Results

Regarding the event-free life expectancy, the age crossover points between the two valve types were 64–65 and 57–58 years for Japanese and American patients, respectively. Regarding the life expectancy, the age crossover points were 88–89 and 64–65 years, respectively, for Japanese and American patients. The lifetime risk of structural valve degeneration was higher in Japanese patients than in American patients. The sensitivity analysis showed that the age crossover points were sensitive to the hazard of bleeding complications.

Conclusions

The long-term clinical outcomes after aortic valve replacement were simulated with a microsimulation model. The results indicated that the age crossover points in the advantages and disadvantages between mechanical valves and bioprostheses may be higher in Japanese patients than in American subjects.

Mechanical compliance and immunological compatibility of fixative-free decellularized/cryopreserved human pericardium

BACKGROUND

The pericardial tissue is commonly used to produce bio-prosthetic cardiac valves and patches in cardiac surgery. The procedures adopted to prepare this tissue consist in treatment with aldehydes, which do not prevent post-graft tissue calcification due to incomplete xeno-antigens removal. The adoption of fixative-free decellularization protocols has been therefore suggested to overcome this limitation. Although promising, the decellularized pericardium has not yet used in clinics, due to the absence of proofs indicating that the decellularization and cryopreservation procedures can effectively preserve the mechanical properties and the immunologic compatibility of the tissue.

PRINCIPAL FINDINGS

The aim of the present work was to validate a procedure to prepare decellularized/cryopreserved human pericardium which may be implemented into cardiovascular homograft tissue Banks. The method employed to decellularize the tissue completely removed the cells without affecting ECM structure; furthermore, uniaxial tensile loading tests revealed an equivalent resistance of the decellularized tissue to strain, before and after the cryopreservation, in comparison with the fresh tissue. Finally, immunological compatibility, showed a minimized host immune cells invasion and low levels of systemic inflammation, as assessed by tissue transplantation into immune-competent mice.

CONCLUSIONS

Our results indicate, for the first time, that fixative-free decellularized pericardium from cadaveric tissue donors can be banked according to Tissue Repository-approved procedures without compromising its mechanical properties and immunological tolerance. This tissue can be therefore treated as a safe homograft for cardiac surgery.

Life expectancy following diagnosis of a vertebral compression fracture

SUMMARY

The life expectancy of vertebral compression fracture (VCF) patients was evaluated as a function of their treatment. Compared to non-operated patients, the kyphoplasty and vertebroplasty patient cohort had 115% and 44% greater adjusted life expectancy, respectively. Kyphoplasty patients had a 34% greater adjusted life expectancy than vertebroplasty patients.

INTRODUCTION

Balloon kyphoplasty and vertebroplasty are minimally invasive procedures for the treatment of painful VCFs. This comparative effectiveness study characterized the life expectancy of VCF patients as a function of their treatment.

METHODS

Life expectancy of VCF patients in the 100% U.S. Medicare dataset (2005-2008) was estimated using a parametric Weibull survival model (adjusted for comorbidities), and compared between operated and non-operated patients as well as between kyphoplasty and vertebroplasty patients. A total of 858,978 patients with a newly diagnosed VCF were identified, including 119,253 kyphoplasty patients (13.9%) and 63,693 vertebroplasty patients (7.4%).

RESULTS

Adjusted life expectancy was 85% greater for operated than non-operated patients (p < 0.001; 95% confidence interval: 82-89%). Compared to non-operated patients, the kyphoplasty and vertebroplasty patient cohort had 115% (p < 0.001; 95% confidence interval: 111-119%) and 44% (p < 0.001; 95% confidence interval: 42-47%) greater adjusted life expectancy, respectively. Kyphoplasty patients had a 34% greater adjusted life expectancy than vertebroplasty patients (p < 0.001; 95% confidence interval: 31-36%). Across all gender-age groups, the median life expectancy predicted by the parametric Weibull model was 2.2-7.3 years greater for operated than non-operated patients.

CONCLUSIONS

Statistically significant and substantial differences in life expectancy were observed between the treated and non-treated cohorts in the Medicare population. Among the treated cohorts, patients in the vertebroplasty group experienced less of a survival benefit than those who received kyphoplasty. The results will be a useful basis for future cost effectiveness studies of VCF treatments for the Medicare population.

Inclusion cylinder method for aortic valve replacement utilising the Ross operation in adults with predominant aortic stenosis - 99% freedom from re-operation on the aortic valve at 15 years

BACKGROUND

To report our experience with the Ross operation in patients with predominant aortic stenosis (AS) using an inclusion cylinder (IC) method.

METHODS

Out of 324 adults undergoing a Ross operation, 204 patients of mean age of 41.3 years (limits 16-62) underwent this procedure for either AS or mixed AS and regurgitation (AS/AR) between October, 1992 and February, 2012, implanting the PA with an IC method. Clinical follow up and serial echo data for this group is 97% complete with late mortality follow up 99% complete.

RESULTS

There has been zero (0%) early mortality, and late survival at 15 years is 98% (96%, 100%). Only one re-operation on the aortic valve for progressive aortic regurgitation (AR) has been required with freedom from re-operation on the aortic valve at 15 years being 99% (96%, 100%). The freedom from all re-operations on the aortic and pulmonary valves at 15 years is 97% (94%, 100%). Echo analysis at the most recent study shows that 98% have nil, trivial or mild AR. Aortic root size has remained stable, shown by long-term (15 year) echo follow up.

CONCLUSIONS

In an experience spanning 19 years, the Ross operation used for predominant AS using the IC method described, results in 99% freedom from re-operation on the aortic valve at 15 years, better than any other tissue or mechanical valve. For adults under 65 years without significant co-morbidities who present with predominant AS, the pulmonary autograft inserted with this technique gives excellent results.

Durability of pericardial versus porcine bioprosthetic heart valves

OBJECTIVES

To compare the probability, and modes, of explantation for Carpentier-Edwards pericardial versus porcine valves.

METHODS

Our porcine series began in 1974 and our pericardial series in 1991, with annual prospective follow-up. We used the Kaplan-Meier method and Cox regression for estimation and analysis of patient mortality, and the cumulative incidence function and competing risks regression for estimation and analysis of valve durability.

RESULTS

Through the end of 2010, we had implanted 506 porcine and 2449 pericardial aortic valves and 181 porcine and 163 pericardial mitral valves. The corresponding total and maximum follow-up years were 3471 and 24, 11,517 and 18, 864 and 22, and 645 and 9. The corresponding probabilities (cumulative incidence function) of any valve explant were 7%, 8%, 22%, and 8%, and of explant for structural valve deterioration were 4%, 5%, 16%, and 5% at 15 years for the first 3 series and at 8 years for the fourth (pericardial mitral valve) series. Using competing risks regression for structural valve deterioration explant, with age, gender, valve size, and concomitant coronary bypass surgery as covariates, a slight (subhazard ratio, 0.79), but nonsignificant, protective effect was found for the pericardial valve in the aortic position and a greater (subhazard ratio, 0.31) and almost significant (P = .08) protective effect of the pericardial valve in the mitral position. Leaflet tear was responsible for 61% of the structural valve deterioration explants in the porcine series and 46% in the pericardial series.

CONCLUSIONS

Using competing risks regression, the pericardial valve had a subhazard ratio for structural valve deterioration explant of less than 1 in both positions, approaching statistical significance in the mitral position. The mode of structural valve deterioration was predominantly leaflet tear for porcine valves and fibrosis/calcification for pericardial valves.

Sutureless perceval aortic valve replacement: results of two European centers

BACKGROUND

The Perceval S bioprosthesis (Sorin Biomedica Cardio Srl, Sallugia, Italy) is a self-expanding valve designed to preserve aortic sinuses and sinotubular junction. We report the midterm results of a prospective, multicenter clinical study evaluating the safety and efficacy of this stented bioprosthesis in patients undergoing aortic valve replacement with or without concomitant procedures.

METHODS

From January 2007 to September 2011, a total of 208 high-risk patients (mean European system for cardiac operative risk evaluation: 8.7±5.3 years) received a Perceval bioprosthesis in 2 European centers. Median follow up was 10±20 months and 100% complete, and the total accumulated follow-up was 156 patient-years. Ten patients have reached a 4-year follow-up. Valve function was assessed in all patients.

RESULTS

Valve implantation resulted in significant improvement of patients' symptoms. Mean preoperative and postoperative gradients were 48.6±18.6 mm Hg and 10.4±4.3 mm Hg, respectively, and preoperative and postoperative mean effective orifice areas were 0.7±0.2 and 1.4±0.4 cm2. Survival at 12 months was 87.1%, success of implantation was 95%, and freedom from reoperation was 96%. In hospital mortality was 2.4%. During follow-up, 9 patients (4%) required reoperation for paravalvular regurgitation; 7 early and 2 late reoperations. Mean cross-clamp time (CCT) and extracorporeal circulation time (ECT) were, respectively, 33±14 minutes and 54±24 minutes, including 45 patients who underwent surgery through ministernotomy. Concomitant coronary bypass was done in 48 patients with mean CCT 43±13 and ECT 68±25 minutes.

CONCLUSIONS

Perceval sutureless is a safe bioprosthesis that can easily be implanted, including by a minimally invasive technique. It provides excellent hemodynamic with significant clinical improvement. Overall, these data confirm the safety and utility of the Perceval bioprosthesis aortic valve replacement for high-risk patients.

Cost-effectiveness analysis of treatments for vertebral compression fractures

BACKGROUND

Vertebral compression fractures (VCFs) can be treated by nonsurgical management or by minimally invasive surgical treatment including vertebroplasty and balloon kyphoplasty.

OBJECTIVE

The purpose of the present study was to characterize the cost to Medicare for treating VCF-diagnosed patients by nonsurgical management, vertebroplasty, or kyphoplasty. We hypothesized that surgical treatments for VCFs using vertebroplasty or kyphoplasty would be a cost-effective alternative to nonsurgical management for the Medicare patient population.

METHODS

Cost per life-year gained for VCF patients in the US Medicare population was compared between operated (kyphoplasty and vertebroplasty) and non-operated patients and between kyphoplasty and vertebroplasty patients, all as a function of patient age and gender. Life expectancy was estimated using a parametric Weibull survival model (adjusted for comorbidities) for 858 978 VCF patients in the 100% Medicare dataset (2005-2008). Median payer costs were identified for each treatment group for up to 3 years following VCF diagnosis, based on 67 018 VCF patients in the 5% Medicare dataset (2005-2008). A discount rate of 3% was used for the base case in the cost-effectiveness analysis, with 0% and 5% discount rates used in sensitivity analyses.

RESULTS

After accounting for the differences in median costs and using a discount rate of 3%, the cost per life-year gained for kyphoplasty and vertebroplasty patients ranged from $US1863 to $US6687 and from $US2452 to $US13 543, respectively, compared with non-operated patients. The cost per life-year gained for kyphoplasty compared with vertebroplasty ranged from -$US4878 (cost saving) to $US2763.

CONCLUSIONS

Among patients for whom surgical treatment was indicated, kyphoplasty was found to be cost effective, and perhaps even cost saving, compared with vertebroplasty. Even for the oldest patients (85 years of age and older), both interventions would be considered cost effective in terms of cost per life-year gained.

Does preservation of the sub-valvular apparatus during mitral valve replacement affect long-term survival and quality of life? A Microsimulation Study

BACKGROUND

Techniques to preserve the sub-valvular apparatus in order to reduce morbidity and mortality following mitral valve replacement have been frequently reported. However, it is uncertain what impact sub-valvular apparatus preservation techniques have on long-term outcomes following mitral valve replacement. This study investigated the effect of sub-valvular apparatus preservation on long-term survival and quality of life following mitral valve replacement.

METHODS

A microsimulation model was used to compare long-term survival and quality-adjusted life years following mitral valve replacement after conventional valve replacement and sub-valvular apparatus preservation. Probabilistic sensitivity analysis and alternative analysis were performed to investigate uncertainty associated with the results.

RESULTS

Our Analysis suggests that patients survive longer if the sub-valvular apparatus are preserved (65.7% SD 1.5%, compared with 58.1% SD 1.6% at 10 years). The quality adjusted life years gained over a 10 year period where also greater after sub-valvular apparatus preservation. (6.54 QALY SD 0.07 QALY, compared with 5.61 QALY, SD 0.07 QALY). The superiority of preservation techniques was insensitive to patient age, parameter or model uncertainty.

CONCLUSION

This study suggests that long-term outcomes may be improved when the sub-valvular apparatus are preserved. Given the lack of empirical data further research is needed to investigate health-related quality of life after mitral valve replacement, and to establish whether outcomes differ between preservation techniques.