Bioprosthetic aortic valve replacement in elderly patients: Meta-analysis and microsimulation

How microsimulation translates outcome estimates to patient lifetime event occurrence in the setting of heart valve disease

Treatment decisions in healthcare often carry lifelong consequences that can be challenging to foresee. As such, tools that visualize and estimate outcome after different lifetime treatment strategies are lacking and urgently needed to support clinical decision-making in the setting of rapidly evolving healthcare systems, with increasingly numerous potential treatments. In this regard, microsimulation models may prove to be valuable additions to current risk-prediction models. Notable advantages of microsimulation encompass input from multiple data sources, the ability to move beyond time-to-first-event analysis, accounting for multiple types of events and generating projections of lifelong outcomes. This review aims to clarify the concept of microsimulation, also known as individualized state-transition models, and help clinicians better understand its potential in clinical decision-making. A practical example of a patient with heart valve disease is used to illustrate key components of microsimulation models, such as health states, transition probabilities, input parameters (e.g. evidence-based risks of events) and various aspects of mortality. Finally, this review focuses on future efforts needed in microsimulation to allow for increasing patient-tailoring of the models by extending the general structure with patient-specific prediction models and translating them to meaningful, user-friendly tools that may be used by both clinician and patient to support clinical decision-making.

Long-Term Clinical and Echocardiographic Outcomes Following the Ross Procedure: A Post Hoc Analysis of a Randomized Clinical Trial

Importance

The Ross procedure as treatment for adults with aortic valve disease (AVD) has been the subject of renewed interest.

Objective

To evaluate the long-term clinical and echocardiographic outcomes following the Ross procedure for the treatment of adults with AVD.

Design, Setting, and Participants

This post hoc analysis of a randomized clinical trial included adult patients (age <69 years) who underwent a Ross procedure for the treatment of AVD, including those with active endocarditis, rheumatic AVD, decreased ejection fraction, and previous cardiac surgery. The trial, conducted from September 1, 1994, to May 31, 2001, compared homograft root replacement with the Ross procedure at a single center. Data after 2010 were collected retrospectively in November and December 2022.

Exposure

Ross procedure.

Main Outcomes and Measures

The primary end point was long-term survival among patients who underwent the Ross procedure compared with that in the age-, country of origin- and sex-matched general population. Secondary end points were freedom from any reintervention, autograft reintervention, or homograft reintervention and time-related valve function, autograft diameter, and functional status.

Results

This study included 108 adults (92 [85%] male) with a median age of 38 years (range, 19-66 years). Median duration of clinical follow-up was 24.1 years (IQR, 22.6-26.1 years; 2488 patient-years), with 98% follow-up completeness. Of these patients, 9 (8%) had active endocarditis and 45 (42%) underwent reoperations. The main hemodynamic lesion was stenosis in 30 (28%) and regurgitation in 49 (45%). There was 1 perioperative death (0.9%). Twenty-five year survival was 83.0% (95% CI, 75.5%-91.2%), representing a relative survival of 99.1% (95% CI, 91.8%-100%) compared with the general population (83.7%). At 25 years, freedom from any reintervention was 71.1% (95% CI, 61.6%-82.0%); from autograft reintervention, 80.3% (95% CI, 71.9%-89.6%); and from homograft reintervention, 86.3% (95% CI, 79.0%-94.3%). Thirty-day mortality after the first Ross-related reintervention was 0% and after all Ross-related reinterventions was 3.8% (n = 1); 10-year survival after reoperation was 96.2% (95% CI, 89.0%-100%).

Conclusions and Relevance

This study found that the Ross procedure provided excellent survival into the third decade postoperatively that was comparable to that in the general population. Long-term freedom from reintervention demonstrated that the Ross procedure may be a durable substitute into late adulthood, showing a delayed but progressive functional decline.

Trial Registration

isrctn.org Identifier: ISRCTN03530985.

Evolving technology: the TRIFLO tri-leaflet mechanical valve without oral anticoagulation: a potential major innovation in valve surgery

The aortic valve is the most frequently diseased valve and aortic stenosis (AS) is the most prevalent valvular heart disease in developed countries. The diseased native aortic valve can be replaced by either a biological or mechanical valve prosthesis. The main concerns relate to durability, the need for oral anticoagulants and the incidence of complications related to this medication. Experimental, computational and biomolecular blood flow studies have demonstrated that the systolic forward flow but also the reverse flow phase at the end of the systole and leakage during the diastolic phase is mainly responsible for platelet activation and thrombosis. Better design of mechanical prosthetic heart valves must ensure smooth closing during flow deceleration and must eliminate high-shear hinge flow during diastole to prevent life-threatening thrombosis. A novel tri-leaflet valve should combine the favorable hemodynamics and the durability of existing mechanical heart valves and eliminate the less favorable characteristics, including the extremely rapid closing. In this paper, we discuss some issues of current mechanical heart valve prostheses and present a new valve design with the potential for significant innovation in the field. The TRIFLO Heart Valve, is a rigid, three-leaflet central flow heart valve prosthesis consisting of an alloyed titanium housing, and three rigid polymer (PEEK) cusps. This valve has a physiological operating mode. During the forward flow phase, the intraventricular pressure opens the leaflets so that blood can freely flow through with little obstruction, and with the deceleration of the blood flow, the leaflets close early and smoothly, minimizing blood flow regurgitation, blood cell damage, and activation of the coagulation cascade. Pre-clinical studies have shown pretty favorable results and a first-in-man study should start very soon.

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.

Differential Immune Response to Bioprosthetic Heart Valve Tissues in the α1,3Galactosyltransferase-Knockout Mouse Model

Structural valve deterioration (SVD) of bioprosthetic heart valves (BHVs) has great clinical and economic consequences. Notably, immunity against BHVs plays a major role in SVD, especially when implanted in young and middle-aged patients. However, the complex pathogenesis of SVD remains to be fully characterized, and analyses of commercial BHVs in standardized-preclinical settings are needed for further advancement. Here, we studied the immune response to commercial BHV tissue of bovine, porcine, and equine origin after subcutaneous implantation into adult α1,3-galactosyltransferase-knockout (Gal KO) mice. The levels of serum anti-galactose α1,3-galactose (Gal) and -non-Gal IgM and IgG antibodies were determined up to 2 months post-implantation. Based on histological analyses, all BHV tissues studied triggered distinct infiltrating cellular immune responses that related to tissue degeneration. Increased anti-Gal antibody levels were found in serum after ATS 3f and Freedom/Solo implantation but not for Crown or Hancock II grafts. Overall, there were no correlations between cellular-immunity scores and post-implantation antibodies, suggesting these are independent factors differentially affecting the outcome of distinct commercial BHVs. These findings provide further insights into the understanding of SVD immunopathogenesis and highlight the need to evaluate immune responses as a confounding factor.

Prognosis and outcome determinants after heart failure diagnosis in patients who underwent aortic valvular intervention

AIMS

To study clinical phenotype, prognosis for all-cause and cardiovascular (CV) mortality and predictive factors in patients with incident heart failure (HF) after aortic valvular intervention (AVI) for aortic stenosis (AS).

METHODS AND RESULTS

In this retrospective, observational study we included patients from the Swedish Heart Failure Registry (SwedeHF) recorded 2003-2016, with AS diagnosis and AVI before HF diagnosis. The AS diagnosis was established according to International Classification of Diseases 10th revision (ICD-10) codes, thus without information concerning clinical or echocardiographical data on the aortic valve disease. The patients were divided into two subgroups: left ventricular ejection fraction (LVEF) ≥ 50% (AS-HFpEF) and <50% (AS-HFrEF). We individually matched three controls with HF from the SwedeHF without AS (control group) for each patient. Baseline characteristics, co-morbidities, survival status and outcomes were obtained by linking the SwedeHF with two other Swedish registries. We used Kaplan-Meier curves to present time to all-cause mortality, cumulative incidence function for time to CV mortality and Cox proportional hazards model to evaluate the relative difference between AS-HFrEF and AS-HFpEF and AS-HF and controls. The crude all-cause mortality was 49.0%, CV mortality 27.9% in AS-HF patients, respectively 44.7% and 26.6% in matched controls. The adjusted risk for all-cause mortality and CV mortality was similar in HF, regardless of LVEF vs. controls. No significant difference in factors predicting higher all-cause mortality was observed in AS-HFrEF vs. AS-HFpEF, except for diabetes (only in AS-HFrEF), with statistically significant interaction predicting death between the two groups.

CONCLUSIONS

In this nationwide SwedeHF study, we characterized incident HF population after AVI. We found no significant differences in all-cause and CV mortality compared with general HF population. They had virtually the same predictors for mortality, regardless of LVEF.

Outcomes of surgical aortic valve replacement over three decades

OBJECTIVE

The study objective was to analyze temporal changes in baseline and procedural characteristics and long-term survival of patients undergoing surgical aortic valve replacement over a 30-year period.

METHODS

A retrospective analysis of patients undergoing surgical aortic valve replacement between 1987 and 2016 in the Erasmus Medical Center (Rotterdam, The Netherlands) was conducted. Patient baseline and procedural characteristics were analyzed in periods according to the date of surgical aortic valve replacement (period A: 1987-1996; B: 1997-2006; C: 2007-2016). Survival status was determined using the Dutch National Death Registry. Relative survival was obtained by comparing the survival after surgical aortic valve replacement with the survival of the age-, sex-, and year-matched general population.

RESULTS

Between 1987 and 2016, 4404 patients underwent SAVR. From period A to C, the mean age increased from 63.9 ± 11.2 years to 66.2 ± 12.3 years (P < .001), and the prevalence of diabetes mellitus, hypertension, hypercholesterolemia, previous myocardial infarction, and previous stroke at baseline increased (P values for trend for all < .001). The prevalence of concomitant procedures increased from 42.4% in period A to 48.3% in period C (P = .004). Bioprosthesis use increased significantly (18.8% in period A vs 67.1% in period C, P < .001). Mean survival after surgical aortic valve replacement was 13.8 years. Relative survival at 20 years in the overall cohort was 60.4% (95% confidence interval, 55.9-65.2) and 73.8% (95% confidence interval, 67.1-81.1) in patients undergoing isolated primary surgical aortic valve replacement.

CONCLUSIONS

Patient complexity has been continuously increasing over the last 30 years, yet long-term survival after surgical aortic valve replacement remains high compared with the age-, sex-, and year-matched general population.

Narrative review of the contemporary surgical treatment of unicuspid aortic valve disease

Unicuspid aortic valve disease (UAVD) is a frequent and long-lasting challenge for adult congenital heart disease centers. UAVD patients become usually symptomatic in their twenties or thirties and require a surgical treatment plan which should respect their complete lifespan combined with an adequate quality of life. Unfortunately, all current surgical strategies of congenital aortic valve disease bear some important limitations: (I) Aortic valve replacement using bioprosthetic valves is associated with early structural degeneration and leads frequently to re-operations. (II) Mechanical valves are commonly associated with lifelong risk of severe bleeding due to oral anticoagulation. (III) Using a pulmonary autograft (i.e., Ross procedure) for aortic valve replacement is associated with excellent long-term results in non-elderly patients. However, failure of pulmonary autograft or pulmonary homograft may require re-operations. (IV) Aortic valve repair or Ozaki procedure is only performed in a few heart centers worldwide and is associated with a limited reproducibility and early patch degeneration, suture dehiscence or increased risk of endocarditis. In contrast to degenerative tricuspid aortic valve disease, UAVD remains relatively understudied and reports on UAVD treatment are rare and usually limited to retrospective single-center observations. For this review, we searched PubMed for papers in the English language by using the search words unicuspid aortic valve, congenital aortic valve, Ross procedure, Ozaki procedure, aortic valve repair, mechanical/bioprosthetic aortic replacement, homograft. We read the abstracts of relevant titles to confirm their relevance, and the full papers were then extracted. References from extracted papers were checked for additional relevant reports. This review summarizes current surgical treatment strategies for UAVD including aortic valve replacement using bioprosthetic or mechanical valves, homografts, pulmonary autografts (i.e., Ross procedure) and aortic valve repair techniques for UAV. Furthermore, Ozaki procedure will be discussed.

Long-term survival after xenograft versus homograft aortic root replacement: Results from a prospective randomized trial

OBJECTIVE

The study objective was to investigate the long-term survival of patients undergoing xenograft versus homograft full root aortic valve replacement.

METHODS

A total of 166 patients requiring aortic valve surgery were randomized to undergo the Freestyle (Medtronic Inc, Minneapolis, Minn) bioprosthesis (N = 90) or a homograft (N = 76) full root aortic valve replacement between 1997 and 2005 in a single institution. Six patients randomly assigned to the homograft crossed over to the Freestyle bioprosthesis because of the unavailability of suitably sized homografts. All surgeons were required to adhere to the standard surgical technique for homograft root implantation previously described. Follow-up was 98.5% complete.

RESULTS

The mean age of the study population was 65 ± 8 years. Coronary artery bypass grafting was associated with root aortic valve replacement in 76 of 166 patients (46%, P = not significant between groups), and overall hospital mortality was 4.8% (8/166, P = not significant between groups). Median follow-up was 13.8 years (range, 0-21.8 years; 2033 patient-years). The Kaplan-Meier survival analysis showed that there was no significant difference in overall survival between the 2 arms at 5, 10, and 15 years. Twenty-year survival was 28.3% ± 5% for the Freestyle group versus 25.1% ± 5.7% for the homograft group (P = .90), which was comparable to the age- and sex-matched UK general population. The freedom from aortic valve reoperation at 20 years was comparable for the Freestyle group versus the homograft group (67.9% ± 8.8% vs 67.2% ± 10.3%, respectively; P = .74).

CONCLUSIONS

This is the first study to investigate the long-term survival of xenograft versus homograft full root aortic valve replacement from a prospective randomized trial. The observed 20-year overall survival and freedom from aortic valve reoperation serve as a benchmark for future studies on interventions for aortic valve disease in the elderly.

Early cost-utility analysis of tissue-engineered heart valves compared to bioprostheses in the aortic position in elderly patients

OBJECTIVES

Aortic valve disease is the most frequent indication for heart valve replacement with the highest prevalence in elderly. Tissue-engineered heart valves (TEHV) are foreseen to have important advantages over currently used bioprosthetic heart valve substitutes, most importantly reducing valve degeneration with subsequent reduction of re-intervention. We performed early Health Technology Assessment of hypothetical TEHV in elderly patients (≥ 70 years) requiring surgical (SAVR) or transcatheter aortic valve implantation (TAVI) to assess the potential of TEHV and to inform future development decisions.

METHODS

Using a patient-level simulation model, the potential cost-effectiveness of TEHV compared with bioprostheses was predicted from a societal perspective. Anticipated, but currently hypothetical improvements in performance of TEHV, divided in durability, thrombogenicity, and infection resistance, were explored in scenario analyses to estimate quality-adjusted life-year (QALY) gain, cost reduction, headroom, and budget impact.

RESULTS

Durability of TEHV had the highest impact on QALY gain and costs, followed by infection resistance. Improved TEHV performance (- 50% prosthetic valve-related events) resulted in lifetime QALY gains of 0.131 and 0.043, lifetime cost reductions of €639 and €368, translating to headrooms of €3255 and €2498 per hypothetical TEHV compared to SAVR and TAVI, respectively. National savings in the first decade after implementation varied between €2.8 and €11.2 million (SAVR) and €3.2-€12.8 million (TAVI) for TEHV substitution rates of 25-100%.

CONCLUSIONS

Despite the relatively short life expectancy of elderly patients undergoing SAVR/TAVI, hypothetical TEHV are predicted to be cost-effective compared to bioprostheses, commercially viable and result in national cost savings when biomedical engineers succeed in realising improved durability and/or infection resistance of TEHV.