Bioprosthetic versus mechanical valves for mitral valve replacement in patients < 70 years: an updated pairwise meta-analysis

BACKGROUND

The ideal conduit for mitral valve replacement (MVR) remains elusive, particularly among younger patients due to increased life expectancy. We perform a pairwise meta-analysis comparing the use of bioprosthetic valves (BPV) and mechanical mitral valves (MMV) in patients < 70 years old undergoing MVR.

METHODS

We comprehensively searched medical databases to identify studies comparing the use of BPV and MMV in patients < 70 years old undergoing MVR. Pairwise meta-analysis was performed using the Mantel-Haenszel method in R version 4.0.2. Outcomes were pooled using the random effect model as risk ratios (RR) with their 95% confidence intervals (95% CI).

RESULTS

16,879 patients from 15 studies were pooled. Compared to MMV, BPV was associated with significantly higher rates of 30-day mortality (RR 1.53, p = 0.0006) but no difference in 30-day stroke (RR 0.70, p = 0.43). At a weighted mean follow-up duration of 14.1 years, BPV was associated with higher rates of long-term mortality (RR 1.28, p = 0.0054). No difference was seen between the two groups for risk of long-term stroke (RR 0.92, p = 0.67), reoperation(RR 1.72, p = 0.12), or major-bleeding (RR 0.57, p = 0.10) at a weighted mean follow-up duration of 11.7, 11.3, and 11.9 years, respectively.

CONCLUSION

The use of MMV in patients < 70 undergoing MVR is associated with lower rates of 30-day/long-term mortality compared to BPV. No significant differences were observed for risk of 30-day/long-term stroke, long-term reoperation, and long-term major bleeding. These findings support the use of MMV in younger patients, although prospective, randomized trials are still needed.

Trends in Isolated Mitral Valve Repair or Replacement Surgery in Australia: A Statewide Cohort Linkage Study

BACKGROUND

Global trends in mitral valve surgery (MVSx) suggest increasing repair compared with replacement, especially in the United States and European countries. The relative use, and outcomes of, MV repair and replacement in Australia are unknown.

METHODS

New South Wales residents who underwent isolated MVSx between 2001 and 2017 were identified from the Admitted-Patient-Data-Collection database. Mortality outcomes were tracked to 31 Dec 2018 and adjusted based on age, sex, urgency of operation, and comorbidity status.

RESULTS

The study cohort comprised 5,693 patients: 2020 (35%) underwent repair (MVr), 1,656 (29%) underwent mechanical replacement (mech.MVR), and 2017 (35%) underwent bioprosthetic replacement (bio.MVR). Respective median ages [interquartile range] were 67 yo [59-75 yo], 64 yo [55-71 yo], and 75 yo [68-80 yo] (p<0.001 across groups). Between 2001 and 2017, total MVSx increased steadily with population growth. Whereas the relative use of MVr remained static (34% to 38%), that for bio.MVR (22% to 50%) and mech.MVR (45% to 13%) changed significantly. MVr had the best outcome with 1.2% in-hospital, 2.5% 1-year, and 21.6% total cumulative mortality during a median follow-up of 6.5 years. Compared to MVr, the adjusted hazard ratio (aHR) for mech.MVR and bio.MVR for long-term mortality were 1.41 (95% confidence interval [CI]=1.24-1.61) and 1.73 (95% CI=1.53-1.95), respectively. Heart failure and sepsis were the main cardiovascular and noncardiovascular causes of death in all groups.

CONCLUSION

In this statewide Australian cohort examined over 17 years, MVr is potentially underutilised despite having superior outcomes to MVR. Access to quality dataset which provides the indication for MVSx and quantitative clinical factors is critical to further improve MVr coverage and outcome MVSx.

Valve-in-Valve Transcatheter Aortic Valve Replacement, with Present-Day Innovations and Up-to-Date Techniques

Approximately 51,000 to 65,000 surgical aortic valve replacement (SAVR) cases are performed in the United States anually. Bioprosthetic degeneration commonly occurs within 10 to 15 years, and nearly 800 redo SAVR cases occur each year. Valve-in-valve transcatheter aortic valve replacement (ViV TAVR) has emerged as a safe and effective alternative, as the Food and Drug Administration approved ViV TAVR with self-expanding transcatheter heart valve in 2015 and balloon-expandable valve in 2017 for failed surgical valves cases at high risk of reoperation. We review ViV TAVR, with specific attention to procedural planning, technical challenges, associated complications, and long-term follow-up.

Hemocompatibility and safety of the Carmat Total Artifical Heart hybrid membrane

The Carmat bioprosthetic total artificial heart (C-TAH) is a biventricular pump developed to minimize drawbacks of current mechanical assist devices and improve quality of life during support. This study aims to evaluate the safety of the hybrid membrane, which plays a pivotal role in this artificial heart. We investigated in particular its blood-contacting surface layer of bovine pericardial tissue, in terms of mechanical aging, risks of calcification, and impact of the hemodynamics shear stress inside the ventricles on blood components. Hybrid membranes were aged in a custom-designed endurance bench. Mechanical, physical and chemical properties were not significantly modified from 9 months up to 4 years of aging using a simulating process. Exploration of erosion areas did not show no risk of oil diffusion through the membrane. Blood contacting materials in the ventricular cavities were subcutaneously implanted in Wistar rats for 30 days as a model for calcification and demonstrated that the in-house anti-calcification pretreatment with Formaldehyde-Ethanol-Tween 80 was able to significantly reduce the calcium concentration from 132 μg/mg to 4.42 μg/mg (p < 0.001). Hemodynamic simulations with a computational model were used to reproduce shear stress in left and right ventricles and no significant stress was able to trigger hemolysis, platelet activation nor degradation of the von Willebrand factor multimers. Moreover, explanted hybrid membranes from patients included in the feasibility clinical study were analyzed confirming preclinical results with the absence of significant membrane calcification. At last, blood plasma bank analysis from the four patients implanted with C-TAH during the feasibility study showed no residual glutaraldehyde increase in plasma and confirmed hemodynamic simulation-based results with the absence of hemolysis and platelet activation associated with normal levels of plasma free hemoglobin and platelet microparticles after C-TAH implantation. These results on mechanical aging, calcification model and hemodynamic simulations predicted the safety of the hybrid membrane used in the C-TAH, and were confirmed in the feasibility study.

Bioprosthetics and repair of complex aerodigestive defects

Aerodigestive defects involving the trachea, bronchi and esophagus are a result of prolonged intubation, operative complications, congenital defects, trauma, radiation and neoplastic disease. The vast majority of these defects may be repaired primarily. Rarely, due the size of the defect, underlying complexity, or unfavorable patient characteristics, primary repair is not possible. One alternative to primary repair is bioprosthetic repair. Materials such as acellular dermal matrix and aortic homograft have been used in a variety of applications, including closure of tracheal, bronchial and esophageal defects. Herein, we review the use of bioprosthetics in the repair of aerodigestive defects, along with the unique advantages and disadvantages of these repairs.

An in vivo analysis of Miromesh--a novel porcine liver prosthetic created by perfusion decellularization

BACKGROUND

Bioprosthetics derived from human or porcine dermis and intestinal submucosa have dense, homogenous, aporous collagen structures that potentially limit cellular penetration, undermining the theoretical benefit of a "natural" collagen scaffold. We hypothesized that Miromesh-a novel prosthetic derived from porcine liver by perfusion decellularization-provides a more optimal matrix for tissue ingrowth.

METHODS

Thirty rats underwent survival surgery that constituted the creation of a 4 × 1 cm abdominal defect and simultaneous bridged repair. Twenty rats were bridged with Miromesh, and 10 rats were bridged with non-cross-linked porcine dermis (Strattice). Ten Miromesh and all 10 Strattice were rinsed in vancomycin solution and inoculated with 10(4) colony-forming units of green fluorescent protein-labeled Staphylococcus aureus (GFP-SA) after implantation. Ten Miromesh controls were neither soaked nor inoculated. No animals received systemic antibiotics. All animals were euthanized at 90 d and underwent an examination of their gross appearance before being sectioned for quantitative bacterial culture and histologic grading. A pathologist scored specimens (0-4) for cellular infiltration, acute inflammation, chronic inflammation, granulation tissue, foreign body reaction, and fibrous capsule formation.

RESULTS

All but one rat repaired with Strattice survived until the 90-d euthanization. All quantitative bacterial cultures for inoculated specimens were negative for GFP-SA. Of nine Strattice explants, none received a cellular infiltration score >0, consistent with a poor tissue-mesh interface observed grossly. Of 10 Miromesh explants also inoculated with GFP-SA, seven of 10 demonstrated cellular infiltration with an average score of +2.7 ± 0.8, whereas sterile Miromesh implants received an average score of 0.8 ± 1.0. Two inoculated Miromesh implants demonstrated acute inflammation and infection on histology.

CONCLUSIONS

A prosthetic generated from porcine liver by perfusion decellularization provides a matrix for superior cellular infiltration compared with non-cross-linked porcine dermis.

Efficacy and safety of novel oral anticoagulants in patients with bioprosthetic valves

PURPOSE

Prosthetic valve replacement is performed in several hundred thousand patients worldwide annually, and many of these patients have or will ultimately develop atrial fibrillation or flutter (AF). Novel oral anticoagulants (NOACs) are not recommended in patients with AF and mechanical valves but have not been evaluated in patients with bioprosthetic valves. This study sought to evaluate the efficacy and safety of NOACs in patients with AF and bioprosthetic valves.

METHODS

A retrospective single-center cohort study was performed on all patients with bioprosthetic valve implantation, for whom a NOAC was prescribed for the indication of AF. Patients were evaluated for thromboembolic events including imaging confirmed ischemic stroke, clinically suspected transient ischemic attack, and major bleeding events (according to International Society on Thrombosis and Hemostasis definition).

RESULTS

In total, 73 patients (26 female, 35.6 %) were identified. NOAC therapy began, on average, 990.0 ± 1029.1 days after bioprosthetic valve implantation for an average duration of 511.8 ± 400.8 days. Aspirin was used concomitantly in a majority of patients (72.6 %). There were no ischemic strokes identified (0.0 %) and one possible TIA (1.4 %). There were 6 (8.2 %) minor and 5 (6.9 %) major bleeding events.

CONCLUSION

The use of NOAC therapy for AF in patients with bioprosthetic valves appears safe and effective in the occurrence of thromboembolic events, however, at the expense of increased bleeding. Larger studies are necessary to confirm these findings.

Is aortic valve repair or replacement with a bioprosthetic valve the best option for a patient with severe aortic regurgitation?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether it is best to repair or replace the aortic valve with a bioprosthesis in young patients with severe aortic regurgitation as the patients do not like to take warfarin for the rest of life. Altogether 74 papers were found using the reported search, of which 10 represented the best evidence to answer the clinical question. The authors, journal, date, country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. The results of the reported studies provided interesting results. All the studies identified are retrospective. Three papers reported the results about the Ross operation for aortic valve (AV) disease. Freedom from autograft reoperation at 10 years was from 81 to 84%, at 15 years 92% and at 18 years 51%. Freedom from aortic insufficiency (AI) (moderate to severe) at 15 years was 89.7%. Four papers reported that freedom from AV reoperation after AV repair at 5 years was from 86 to 94% and at 8 years was from 83 to 93%. Freedom from recurrent AI (>2+) at 5 years was from 85 to 94%. One study showed that reoperation-free survival after AV repair for rheumatic valve disease at 160 months was 85%. Two papers compared AV repair with aortic valve replacement (AVR) with a bioprosthetic valve and found that freedom from AV reoperation at 5 years was from 90 to 91% for the repair group and 94 to 98% for AVR. Freedom from AI (moderate or severe) at 5 years was 79% for the repair group and 94% for AVR. Aortic valve repair yielded good early and mid-term results. It is a viable alternative to replacement with a bioprosthesis, especially for young patients who did not like to take warfarin. The Ross operation appeared to be a good choice for selected patients with AV disease.