Durability of bioprosthetic cardiac valves

Left atrial Thrombus formation after discontinuation of anticoagulation in patient with severe bioprosthetic mitral stenosis

BACKGROUND

Mitral valve stenosis can be a highly symptomatic condition with significant complications if left untreated. In such cases, mitral valve replacement with a bioprosthetic or mechanical valve may be a viable solution to prevent progressive disease. Current guidelines do not recommend continued anticoagulation beyond 6 months for patients who have undergone bioprosthetic valve replacement without a separate indication for anticoagulation. With this case discussion we aim to 1) Review the current indications for anticoagulation for bioprosthetic mitral valves in patients without atrial fibrillation and 2) Discuss the constellation of comorbidities that may affect the decision to begin anticoagulation therapy.

CASE PRESENTATION

We present a case describing a 55-year-old male with end-stage renal disease, coronary artery disease with coronary artery bypass graft surgery, and bioprosthetic mitral valve replacement 2 years prior with rapid degeneration of the replaced valve and on warfarin without a clear indication for anticoagulation. The patient was admitted for symptomatic, severe mitral stenosis and consideration of transcatheter mitral valve-in-valve replacement. During hospital admission, warfarin was discontinued and replaced with prophylactic anticoagulation. However, 8 days after warfarin cessation an intraoperative transesophageal echocardiography revealed a newly developed large left atrial thrombus leading to cancellation of the planned operation.

CONCLUSIONS

This patient developed a left atrial thrombus after discontinuing warfarin in the setting of rapidly deteriorating bioprosthetic valve stenosis and vascular comorbidities. The decision to discontinue warfarin was made in concordance with current guidelines, which do not indicate systemic anticoagulation post 3-6 months after bioprosthetic valve replacement without separate indication for anticoagulation. This case identifies the need to investigate rebound hypercoagulability and further risk stratify comorbidities which may independently increase the risk of clot formation in the setting of severe mitral valve stenosis.

Ross procedure versus pulmonary homograft versus mechanical valve versus bioprosthetic valve versus Ozaki procedure for surgical aortic valve replacement: a frequentist network meta-analysis

BACKGROUND

There has been a resurgence in interest regarding the Ross procedure due to recent publications detailing positive long-term outcomes. Conversely, surgical aortic valve replacement (SAVR) with a pulmonary homograft (PH), mechanical (MV), bioprosthetic (BV), or the Ozaki procedure each has its own technical advantages and disadvantages. Therefore, we performed a network meta-analysis (NMA) comparing other alternatives to Ross procedure.

METHODS

Medical databases were comprehensively searched for studies comparing the Ross procedure with AVR using a PH, MV, BV, or the Ozaki procedure. Outcomes were pooled as risk ratios (RR) with their 95% confidence intervals (95% CI).

RESULTS

A total of 7816 patients were pooled for our NMA from 24 studies. Compared to Ross procedure, both BV and MV were associated with significantly higher rates of 30-day mortality of RR (2.37, 95% CI 1.20-4.67) and (1.88 95% CI 1.04-3.40), respectively, with no significant difference regarding PH or Ozaki. However, only MV was associated with a higher risk of 30-day stroke (RR 8.42, 95% CI 1.57-45.23) with no significant difference in the other alternatives, as well as 30-day MI which showed no significant differences between any of the aortic conduits compared to the Ross procedure. Regarding 30-day major bleeding, MV was associated with a higher when compared to the Ross procedure RR (4.58, 95% CI 1.94-10.85), PH was associated with a lower risk of major bleeding with RR (0.35, 95% CI 0.17-0.71), and BV showed no significant difference. With a mean follow-up duration of 8.5 years compared to the Ross procedure, BV, PH, and MV were associated with a higher risk of long-term mortality with RR (1.89, 95% CI 1.38-2.58), (1.38, 95% CI 1.0-1.87), and (1.94, 95% CI 1.52-2.47), respectively, with the Ozaki procedure showed no significant difference. Regarding long-term stroke-with a mean of 6.3-year follow-up duration-there were no significant differences between any of the aortic conduits compared to the Ross procedure. Nevertheless, long-term need for reintervention-with a mean follow-up duration of 17.5 years-was significant of higher risk with both BV and PH with RR (3.28, 95% CI 1.21-8.84) and (2.42, 95% CI 1.05-5.58), respectively, compared to Ross procedure with MV and Ozaki having no significant difference.

CONCLUSIONS

The Ross procedure is a viable treatment option for patients undergoing SAVR, showing promising outcomes at short- and long-term follow-ups.

Trends in surgical aortic valve replacement in pre- and post-transcatheter aortic valve replacement eras at a structural heart center

Background

The advent of transcatheter aortic valve replacement (TAVR) has directly impacted the lifelong management of patients with aortic valve disease. The U.S. Food and Drug Administration has approved TAVR for all surgical risk: prohibitive (2011), high (2012), intermediate (2016), and low (2019). Since then, TAVR volumes are increasing and surgical aortic valve replacements (SAVR) are decreasing. This study sought to evaluate trends in isolated SAVR in the pre- and post-TAVR eras.

Methods

From January 2000 to June 2020, 3,861 isolated SAVRs were performed at a single academic quaternary care institution which participated in the early trials of TAVR beginning in 2007. A formal structural heart center was established in 2012 when TAVR became commercially available. Patients were divided into the pre-TAVR era (2000-2011, n = 2,426) and post-TAVR era (2012-2020, n = 1,435). Data from the institutional Society of Thoracic Surgeons National Database was analyzed.

Results

The median age was 66 years, similar between groups. The post-TAVR group had a statistically higher rate of diabetes, hypertension, dyslipidemia, heart failure, more reoperative SAVR, and lower STS Predicted Risk of Mortality (PROM) (2.0% vs. 2.5%, p < 0.0001). There were more urgent/emergent/salvage SAVRs (38% vs. 24%) and fewer elective SAVRs (63% vs. 76%), (p < 0.0001) in the post-TAVR group. More bioprosthetic valves were implanted in the post-TAVR group (85% vs. 74%, p < 0.0001). Larger aortic valves were implanted (25 vs. 23 mm, p < 0.0001) and more annular enlargements were performed (5.9% vs. 1.6%, p < 0.0001) in the post-TAVR era. Postoperatively, the post-TAVR group had less blood product transfusion (49% vs. 58%, p < 0.0001), renal failure (1.4% vs. 4.3%, p < 0.0001), pneumonia (2.3% vs. 3.8%, p = 0.01), shorter lengths of stay, and lower in-hospital mortality (1.5% vs. 3.3%, p = 0.0007).

Conclusion

The approval of TAVR changed the landscape of aortic valve disease management. At a quaternary academic cardiac surgery center with a well-established structural heart program, patients undergoing isolated SAVR in the post-TAVR era had lower STS PROM, more implantation of bioprosthetic valves, utilization of larger valves, annular enlargement, and lower in-hospital mortality. Isolated SAVR continues to be performed in the TAVR era with excellent outcomes. SAVR remains an essential tool in the lifetime management of aortic valve disease.

The Ross procedure in children: a systematic review

Background

The Ross procedure involves autograft transplantation of the native pulmonary valve into the aortic position and reconstruction of the right ventricular outflow tract (RVOT) with a homograft. The operation offers the advantages of a native valve with excellent hemodynamic performance, the avoidance of anticoagulation, and growth potential. Conversely, the operation is technically demanding and imposes the risk of turning single-valve disease into double-valve disease. This systematic review reports outcomes of pediatric patients undergoing the Ross procedure.

Methods

An electronic search identified studies reporting outcomes on pediatric patients (mean age <18 years, max age <21 years) undergoing the Ross procedure. Long-term outcomes, including early mortality, late mortality, sudden unexpected unexplained death, reoperation due to failure of the pulmonary autograft or RVOT reconstruction, thromboembolic events, bleeding events, and endocarditis-related complications, were evaluated.

Results

Upon review of 2,035 publications, 30 studies and 3,156 pediatric patients were included. Patients had a median age of 9.5 years and median follow-up period of 5.7 years. Early mortality rates varied from 0.0 to 17.0% and were increased in the neonatal population. Late mortality rates were much lower (0.04-1.83%/year). Reoperation due to pulmonary autograft failure occurred at rates of 0.37-2.81%/year and reoperation due to RVOT reconstruction failure was required at rates of 0.34-4.76%/year. Thromboembolic, bleeding, and endocarditis events were reported to occur at rates of 0.00-0.58, 0.00-0.39, and 0.00-1.68%/year, respectively.

Conclusions

The Ross operation offers a durable aortic valve replacement (AVR) option in the pediatric population that offers favorable survival, excellent hemodynamics, growth potential, decreased risk of complications, and avoidance of anticoagulation. Larger multi-institutional registries focusing on pediatric patients are necessary to provide more robust evidence to further support use of the Ross procedure in this population.

Current Devices in Mitral Valve Replacement and Their Potential Complications

Mitral regurgitation is one of the most prevalent valvulopathies worldwide, and its surgical treatment is not feasible in all cases. The elderly and frail with several comorbidities and left ventricular dysfunction are often managed conservatively. Percutaneous treatment (repair or replacement) of the mitral valve has emerged as a potential option for those patients who are at a high risk for surgery. Mitral valve repair with the Mitraclip device proved both increased safety and mortality reduction in patients with severe mitral regurgitation. On the other hand, in the last decade, percutaneous mitral replacement opened new frontiers in the field of cardiac structural interventions. There are few mitral devices; some are in the early phase of development and some are waiting for CE mark of approval. The evolution of these devices was more complicated compared to the aortic technology due to the native mitral valve's complexity and access. This review aims to provide an overview of the current devices, their specific features, and their potential complications.

Pressurized Perfusion System for Obtaining Completely Acellular Pulmonary Valve Scaffolds for Tissue Engineering

Introduction. Xenogeneic tissues decellularization represents the obtaining process of extracellular matrix derived scaffolds. Most antigens being cell based, non-immunogenicity is obtained by cells removal. Scaffolds are temporary structures with biologic and mechanical role. Scaffolds, stem cells and bioreactors represent premise of regenerative medicine, aiming towards the ideal valvular substitute. In previous studies, we decellularized pulmonary valves root by immersion histology revealing cellular residue, requiring a more efficient approach. We hypothesized that immersion is insufficient and thus a pressure gradient was added.

Material and Method. This is part of a grant approved by the UMFTS. Eleven porcine pulmonary valves were included in the study: n=6 underwent immersion decellularization and n=5 were cyclically perfused with a 20-25mmHg pressure gradient during a 10-day protocol. The acellular valves obtained underwent a quality control using DAPI (4′,6-diamidino-2-phenylindol) nuclear staining, histological Haematoxylin-Eosin, DNA extraction and quantification, harvested from different structural levels: arterial wall, sinus, cusp.

Results. Histological assessments highlighted integrity of extracellular matrix in both groups and overall cells absence at the different levels of valvular structures analyzed. Immersion decellularized valves exhibited DAPI positive structures identified as potential residual nucleic material. Comparatively, the perfusion decellularized valves, lacked in those structures, result confirmed by DNA extraction and quantitation procedure.

Conclusions. Perfusion decellularization represents a feasible approach to obtain acellular cardiac valvular scaffolds derived from the extracellular matrix, being superior to immersion decellularization method. Their nonimmunogenic potential is underlined by total absence of nuclei. The process is fast, allowing production of an abundant number of valvular biomaterials in a short time.

Surgically implanted aortic valve bioprostheses deform after implantation: insights from computed tomography

OBJECTIVE

Little is known about the prevalence and degree of deformation of surgically implanted aortic biological valve prostheses (bio-sAVRs). We assessed bio-sAVR deformation using multidetector-row computed tomography (MDCT).

METHODS

Three imaging databases were searched for patients with MDCT performed after bio-sAVR implantation. Minimal and maximal valve ring diameters were obtained in systole and/or diastole, depending on the acquired cardiac phase(s). The eccentricity index (EI) was calculated as a measure of deformation as (1 - (minimal diameter/maximal diameter)) × 100%. EI of < 5% was considered none or trivial deformation, 5-10% mild deformation, and > 10% non-circular. Indications for MDCT and implanted valve type were retrieved.

RESULTS

One hundred fifty-two scans of bio-sAVRs were included. One hundred seventeen measurements were performed in systole and 35 in diastole. None or trivial deformation (EI < 5%) was seen in 67/152 (44%) of patients. Mild deformation (EI 5-10%) was seen in 59/152 (39%) and non-circularity was found in 26/152 (17%) of cases. Overall, median EI was 5.5% (IQR 3.4-7.8). In 77 patients, both systolic and diastolic measurements were performed from the same scan. For these scans, the median EI was 6.5% (IQR 3.4-10.2) in systole and 5.1% (IQR3.1-7.6) in diastole, with a significant difference between both groups (p = 0.006).

CONCLUSIONS

Surgically implanted aortic biological valve prostheses show mild deformation in 39% of cases and were considered non-circular in 17% of studied valves.

KEY POINTS

• Deformation of surgically implanted aortic valve bioprostheses (bio-sAVRs) can be adequately assessed using MDCT. • Bio-sAVRs show at least mild deformation (eccentricity index > 5%) in 56% of studied cases and were considered non-circular (eccentricity index > 10%) in 17% of studied valves. • The higher deformity rate found in bio-sAVRs with (suspected) valve pathology could suggest that geometric deformity may play a role in leaflet malformation and thrombus formation similar to that of transcatheter heart valves.

Comparison of Biological and Mechanical Prostheses for Heart Valve Surgery: A Systematic Review of Randomized Controlled Trials

Background

The choice of a mechanical (MP) or biological prosthesis (BP) for patients with valvular heart disease undergoing replacement is still not a consensus.

Objective

We aimed to determine the clinical outcomes of MP or BP placement in those patients.

Methods

We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) that compared biological prostheses and mechanical prostheses in patients with valvular heart diseases and assessed the outcomes. RCTs were searched in the MEDLINE, EMBASE, LILACS, CENTRAL, SCOPUS and Web of Science (from inception to November 2014) databases. Meta-analyses were performed using inverse variance with random effects models. The GRADE system was used to rate the quality of the evidence. A P-value lower than 0.05 was considered significant.

Results

A total of four RCTs were included in the meta-analyses (1,528 patients) with follow up ranging from 2 to 20 years. Three used old generation mechanical and biological prostheses, and one used contemporary prostheses. No significant difference in mortality was found between BP and MP patients (risk ratio (RR = 1.07; 95% CI 0.99-1.15). The risk of bleeding was significantly lower in BP patients than MP patients (RR = 0.64; 95% CI 0.52-0.78); however, reoperations were significantly more frequent in BP patients (RR = 3.60; 95% CI 2.44-5.32). There were no statistically significant differences between BP and MP patients with respect to systemic arterial embolisms and infective endocarditis (RR = 0.93; 95% CI 0.66-1.31, RR = 1.21; CI95% 0.78-1.88, respectively). Results in the trials with modern and old prostheses were similar.

Conclusions

The mortality rate and the risk of thromboembolic events and endocarditis were similar between BP and MP patients. The risk of bleeding was approximately one third lower for BP patients than for MP patients, while the risk of reoperations was more than three times higher for BP patients.

Perioperative management of transcatheter, aortic and mitral, double valve-in-valve implantation during pregnancy through left ventricular apical approach

Pregnant women with stenotic degeneration of bioprosthetic cardiac valves may require another valve replacement procedure when their symptoms deteriorate with progression of pregnancy, but fetal mortality is higher with cardiac surgery done on cardiopulmonary bypass. Transcatheter valve-in-valve implantation may help to improve the fetal and maternal outcomes in these situations. Double valve-in-valve implantation is rare and has not been reported in a pregnant patient. We report, for the first time, the case of a pregnant woman with stenotic bioprosthetic valves in the mitral and aortic positions, who underwent a successful concomitant, transcatheter, double valve-in-valve implantation through the left ventricular apical route during the second trimester of her precious pregnancy.

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.

Comparison of clinical outcomes in patients undergoing mitral valve replacement with mechanical or biological substitutes: a 20 years cohort

Background

The choice of prosthesis for mitral valve replacement still remains controversial. This study assessed mortality, bleeding events and reoperation in patients who underwent mitral valve replacement surgery with biological or mechanical substitutes.

Methods

A total of 352 patients who underwent mitral valve replacement surgery between 1990 and 2008 with 5 to 23 years of follow-up were retrospectively evaluated in a cohort study.

Results

The 5, 10, 15 and 20 year survival rates after surgery using a mechanical substitute were 87.7%, 74.2%, 69.3% and 69.3%, respectively, while after surgery with a biological substitute, they were 87.6%, 71.0%, 64.2% and 56.6%, respectively. There was no significant difference between the two groups (p = 0.38). In the multivariate analysis, the factors associated with death were age, bleeding events and renal failure. The probabilities of remaining free of reoperation at 5, 10, 15 and 20 years after surgery using a mechanical substitute were 94.4%, 92.7%, 92.7% and 92.7%; after surgery with a bioprosthesis, they were 95.9%, 86.4%, 81.2% and 76.5%, respectively (p = 0.073). There was a significantly higher incidence of reoperation for the bioprosthetic valve replacement group (p = 0.008). The probabilities of remaining free of bleeding events at 5, 10, 15 and 20 years after surgery using a mechanical substitute were 95.0%, 91.0%, 89.6% and 89.6%, respectively, while after surgery with a bioprosthesis, they were 96.9%, 94.0%, 94.0% and 94.0%, (p = 0.267).

Conclusions

The authors concluded that: 1) mortality during follow-up was statistically similar for both groups; 2) there was a greater tendency to reoperation in the bioprosthesis group; 3) the probability of remaining free from reoperation remained unchanged after 10 years’ follow-up for patients with mechanical substitute valves; 4) the probability of remaining fee from bleeding events remained unchanged after 10 years’ follow-up for patients given bioprostheses; 5) the baseline characteristics of patients were the greatest determinants of later mortality after surgery; 6) the type of prosthesis was not an independent predictive factor of any of the outcomes tested in the multivariate analysis.

Pregnancy outcome and follow-up cardiac outcome in women with aortic valve replacement

OBJECTIVES

To compare the maternal, fetal and cardiac outcomes in women who have undergone aortic valve replacement.

METHOD

Retrospective observational study of all women with aortic valve replacement, who underwent a pregnancy (1998-2012). Maternal-, fetal- and valve-related cardiac outcomes were assessed.

RESULTS

Thirty-two pregnancies in 16 women with aortic valve replacement (nine bioprosthetic, six Ross and 17 mechanical) were evaluated. There were no adverse maternal events in the bioprosthetic and Ross groups but three in the mechanical group. Fetal loss rate was highest in the mechanical valve pregnancies (53%). One woman in the bioprosthetic group needed valve re-operation, and one woman in the mechanical valve group died. There was no difference in the change of Vmax over the follow-up between the valves (p = 0.25).

CONCLUSIONS

There was no difference in deterioration between aortic valve replacements during and after pregnancy. The highest risk of maternal and fetal complications occurred in the mechanical valve group.

Can statins improve outcomes after isolated cardiac valve surgery? A systematic literature review

BACKGROUND

HMG CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase inhibitors, or statins, have been associated with an improvement in outcomes after coronary artery surgery for some time; however, their role in isolated valve surgery (IVS) remains undetermined.

HYPOTHESIS

The pleiotropic effects of statins may produce similar beneficial effects on outcomes after IVS.

METHODS

A systematic review of the literature was performed investigating the role of statins in bioprosthetic valve replacement.

RESULTS

Nine observational studies (7 retrospective, 2 prospective) incorporating a total of 18 154 patients were found investigating the role of statin therapy in bioprosthetic valve replacement.

CONCLUSIONS

There is presently insufficient evidence to recommend routine statin therapy in IVS, unless concomitant hypercholesterolemia or coronary artery disease is present. A prospective study clearly defining the dose, type, and duration of therapy is now required to finally clarify whether statins alone confer a postoperative benefit in these patients.

Stented bioprostheses in aortic position

INTRODUCTION

Biological stented prostheses are currently the main type of prosthetic valve used for aortic valve replacement. The ratio of bioprotheses to mechanical prostheses has switched in the last 15 years; the percentage of biological  prostheses implanted has risen from 30 % to 85 %. Moreover the total number of implanted stented bioprostheses remained stable over the last years despite competing procedures like stentless prostheses or transcatheter aortic valve implantation.

METHODS

A literature search of all published aortic valve replacement studies was performed from January 2000 through May 2012.

RESULTS

The recommendations guiding the type of heart valve replacement have been revised in recent years. Of particular interest are the new generation of biological prostheses with extended durability, a decrease in mortality of reoperation and an increase in life expectancy. Comorbidities such as chronic renal insufficiency or chronic atrial fibrillation are no longer contraindications to bioprostheses.

CONCLUSION

Overall, even in face of more innovative biological alternatives the implantation of stented bioprostheses is still a very interesting option and represents actually the most frequent valve implantation technique for aortic stenosis.