Early Clinical and Hemodynamic Outcomes After Stented and Stentless Aortic Valve Replacement: Results From a Randomized Controlled Trial

Midterm Outcomes of Stented Versus Stentless Bioprosthetic Valves After Aortic Root Replacement

To determine the impact of aortic root replacement (ARR) with a stentless bioprosthetic valve on midterm outcomes compared to a stented bioprosthetic valve-graft conduit. This was an observational study of aortic root operations from 2010 to 2018. All patients with a complete ARR for nonendocarditis reasons were included, while patients undergoing valve-sparing root replacements or primary aortic valve replacement or repair were excluded. Of the patients with a complete ARR, bioprosthetic valve implants were included, while mechanical valve implants were excluded. Patients were dichotomized into the stented ARR group and the stentless ARR group. A total of 1:1 nearest neighbor propensity matching was employed to assess the association of stentless valves with short-term and midterm outcomes. A total of 455 patients underwent a complete ARR with a bioprosthetic valve implant for nonendocarditis reasons, of which 212 (46.6%) received a stented valve, while 243 (53.4%) received a stentless valve. After matching, postoperative outcomes were similar across each group (P > 0.05), including operative mortality and adverse neurologic events. Median follow-up for the entire cohort was 4.41 years (95% CI: 4.01, 4.95). At 1 year follow-up, aortic regurgitation ≥ 2+ and ejection fraction were similar across each group (P > 0.05); however, the stentless valve group had lower aortic valve velocity and transvalvular pressure gradient. Finally, reoperations and survival were similar for each group over the study's follow-up (P > 0.05). Stentless valves may provide hemodynamic benefits after ARR; however, the clinical impact of those benefits for survival and reoperation may not yet be evident in the midterm.

Stentless Pericarbon Freedom Versus Stented Perimount Aortic Bioprosthesis: Propensity-Matched Long-Term Follow-Up

OBJECTIVE

Stentless aortic valves have shown superior hemodynamic performance and faster left ventricular mass regression compared to stented bioprostheses. Yet, controversies exist concerning the durability of stentless valves. This case-matched study compared short- and long-term clinical outcomes of stentless LivaNova-Sorin Pericarbon Freedom™ (SPF) and stented Carpentier-Edwards Perimount (CEP) aortic prostheses.

METHODS

From 2003 through 2006, 134 consecutive patients received aortic valve replacement with SPF at our institution. This cohort was matched, according to 20 preoperative clinical parameters, with a control group of 390 patients who received CEP prosthesis during the same time. The resulting 55 + 55 matched patients were analyzed for perioperative results and long-term clinical outcomes.

RESULTS

Early mortality was 0% for both groups. Lower transvalvular gradients were found in the SPF group (10.6 ± 2.9 versus 15.7 ± 3.1 mmHg, P < 0.001). Overall late mortality (mean follow-up: 10.03 years) was similar for both groups (50.1% versus 42.8%, P = 0.96). Freedom from structural valve degeneration (SVD) at 13 years was similar for both groups (SPF = 92.3%, CEP = 73.9%, P = 0.06). Freedom from aortic valve reinterventions did not differ (SPF = 92.3%, CEP = 93.5%, P = 0.55). Gradients at 13-year follow-up remained significantly lower in SPF group (10.0 ± 4.5 versus 16.2 ± 9.5 mmHg, P < 0.001). Incidence of acute bacterial endocarditis (ABE) and major adverse cardiovascular and cerebrovascular events (MACCE) was similar.

CONCLUSIONS

SPF and CEP demonstrated comparable long-term outcomes related to late mortality, SVD, aortic valve reinterventions, and incidence of ABE and MACCE. Superior hemodynamic performance of SPF over time can make this valve a suitable choice in patients with small aortic root and large body surface area.

Recent development and biomedical applications of decellularized extracellular matrix biomaterials

Decellularized matrix (dECM) is isolated extracellular matrix of tissues from its original inhabiting cells, which has emerged as a promising natural biomaterial for tissue engineering, aiming at support, replacement or regeneration of damaged tissues. The dECM can be easily obtained from tissues/organs of various species by adequate decellularization methods, and mimics the structure and composition of the native extracellular matrix, providing a favorable cellular environment. In this review, we summarize the recent developments in the preparation of dECM materials, including decellularization, crosslinking and sterilization. Also, we cover the advances in the utilization of dECM biomaterials in regeneration medicine in pre-clinic and clinical trials. Moreover, we highlight those emerging medical benefits of dECM beyond tissue engineering, such as cell transplantation, in vitro/in vivo model and therapeutic cues delivery. With the advances in the preparation and broader application, the dECM biomaterials could become the gold scaffold and pharmaceutical excipients in medical sciences.

Stented versus Stentless Aortic Valve Replacement in Patients with Small Aortic Root: A Systematic Review and Meta-Analysis

Objective

The aim of the study was to compare hemodynamic and perioperative outcomes of stented against stentless aortic valve replacement in patients with small aortic root (21 mm or less).

Methods

A comprehensive search was undertaken among the four major databases (PubMed, Embase, Scopus, and Ovid) to identify all randomized and nonrandomized controlled trials comparing stentless to stented bioprosthetic valves in small aortic root patients. Odds ratios, weighted mean differences, or standardized mean differences and their 95% confidence intervals were analyzed.

Results

A total of seven studies with a total of 965 patients fulfilled the inclusion criteria. There was no significant difference in preoperative baselines including mean age between both groups ( P = 0.08), peak aortic valve gradient ( P = 0.06), and effective orifice area ( P = 0.28), whereas higher mean aortic valve gradient in the stented group ( P = 0.007). No difference in cardiopulmonary bypass time ( P = 0.74), aortic cross-clamp times ( P = 0.88), intensive care unit stay ( P = 0.13), and stroke rate ( P = 0.56) were noted. However, stented group of patients showed higher rate of patient prosthesis mismatch ( P = 0.0001) and longer total hospital stay ( P = 0.002). Postoperatively, stentless group showed lower peak and mean aortic valve gradient ( P = 0.003 and P = 0.008, respectively) with a better effective orifice area ( P < 0.00001) at 6 months of follow-up. Mortality rates while in-hospital and at 1 year were similar in both groups ( P = 0.94 and P = 0.86, respectively).

Conclusions

Stentless aortic valves offer superior short-term hemodynamic outcomes in patients with small aortic root when compared with stented aortic valves. Although both groups have similar perioperative complications rates, stentless valves bring about a shorter hospital stay. A further large multicenter randomized controlled trial should address the longer-term benefit of stentless aortic valve over stented valve.

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

OBJECTIVE

To support decision-making in aortic valve replacement (AVR) in elderly patients, we provide a comprehensive overview of outcome after AVR with bioprostheses.

METHODS

A systematic review was conducted of studies reporting clinical outcome after AVR with bioprostheses in elderly patients (mean age ≥70 years; minimum age ≥65 years) published between January 1, 2000, to September 1, 2016. Reported event rates and time-to-event data were pooled and entered into a microsimulation model to calculate life expectancy and lifetime event risks.

RESULTS

Forty-two studies reporting on 34 patient cohorts were included, encompassing a total of 12,842 patients with 55,437 patient-years of follow-up (pooled mean follow-up 5.0 ± 3.3 years). Pooled mean age was 76.5 ± 5.5 years. Pooled early mortality risk was 5.42% (95% confidence interval [CI], 4.49-6.55), thromboembolism rate was 1.83%/year (95% CI, 1.28-3.61), and bleeding rate was 0.75%/year (95% CI, 0.50-1.11). Structural valve deterioration (SVD) was based on pooled time to SVD data (Gompertz; shape: 0.124, rate: 0.003). For a 75-year-old patient, this translated to an estimated life expectancy of 9.8 years (general population: 10.2 years) and lifetime risks of bleeding of 7%, thromboembolism of 17%, and reintervention of 9%.

CONCLUSIONS

The low risks of SVD and reintervention support the use of bioprostheses in elderly patients in need of AVR. The estimated life expectancy after AVR was comparable with the general population. The results of this study inform patients and clinicians about the expected outcomes after bioprosthetic AVR and thereby support treatment decision-making. Furthermore, our results can be used as a benchmark for long-term outcomes after transcatheter aortic valve implantation in patients who were eligible for surgery and other (future) alternative treatments (eg, tissue-engineered heart valves).

Transcatheter aortic valve-in-valve implantation in failed stentless bioprostheses

OBJECTIVE

To compare the safety and efficacy of transcathether aortic valve-in-valve implantation (ViV-TAVI) in degenerated stentless bioprostheses with failed stented valves and degenerated native aortic valves.

INTRODUCTION

Little is known about ViV-TAVI in degenerated stentless valves.

METHODS

Out of 45 ViV-TAVI procedures reported in the POL-TAVI registry, 20 failed stentless valves were compared with 25 stented prostheses and propensity-matched with 45 native TAVI cases. The mean follow-up was 633 (95% confidence interval [CI], 471-795) days and Valve Academic Research Consortium-2 (VARC-2) definitions were applied.

RESULTS

Patients with degenerated stentless valves were younger (65.6, CI 58-73.1 years vs 75.6, CI 72.2-78 [stented] vs 80.1, CI 78.7-81.6 y. [native], P < 0.001). Implantation was required later after surgery (11.5, CI 8-14.9 years) in the stentless cohort as compared with the stented one (6.2, CI 4.7-7.6 years, P = 0.006). ViV-TAVI in the stentless group was also associated with larger amount of contrast (211, CI 157-266 mL vs 135, CI 104-167 mL [stented] vs 132 (119-145) mL [native], P = 0.022). Using VARC-2 composite endpoints, ViV-TAVI in stentless prostheses was characterized by a lower device success (50% vs 76% in stented vs 88.9% in native TAVI, P < 0.001), but comparable early safety up to 30 days (73.7% vs 84% vs 81.8%, respectively, log-rank P = 0.667) and long-term clinical efficacy beyond 30 days (72.2% vs 72% vs 73.8%, respectively, log-rank P = 0.963).

CONCLUSIONS

Despite technical challenges and a lower device success, ViV-TAVI in stentless aortic bioprostheses achieves similar safety, efficacy, and functional improvement as in stented or degenerated native valves.

Biological aortic valve replacement: advantages and optimal indications of stentless compared to stented valve substitutes. A review

Controversy still surrounds the optimal biological valve substitute for aortic valve replacement. In light of the current literature, we review advantages and optimal indications of stentless compared to stented aortic bio-prostheses. Recent meta-analyses, prospective randomized controlled trials and retrospective studies comparing the most frequently used stentless and stented aortic bio-prostheses were analyzed. In the present review, the types and implantation techniques of the bio-prosthesis that are seldom taken into account by most studies and reviews were integrated in the interpretation of the relevant reports. For stentless aortic root bio-prostheses, full-root vs. sub-coronary implantation offered better early transvalvular gradients, effective orifice area and left ventricular mass regression as well as late freedom from structural valve deterioration in retrospective studies. Early mortality and morbidity did not differ between the stentless and stented aortic bio-prostheses. Early transvalvular gradients, effective orifice area and regression of left ventricular hypertrophy were significantly better for stentless, especially as full-root, compared to stented bio-prostheses. The long-term valve-related survival for stentless aortic root and Toronto SPV bio-prosthesis was as good as that for stented pericardial aortic bio-prostheses. For full-root configuration this survival advantage was statistically significant. There seems to be not one but different ideal biological valve substitutes for different subgroups of patients. In patients with small aortic root or exposed to prosthesis-patient mismatch full-root implantation of stentless bio-prostheses may better meet functional needs of individual patients. Longer follow-ups on newer generation of stented bio-prostheses are needed for comparison of their hemodynamic performance with stentless counterparts especially in full-root configuration.

Current indications for stentless aortic bioprostheses

The best aortic prostheses have been debated for decades. The introduction of stentless aortic bioprostheses was aimed at improving hemodynamics and potentially the durability of aortic bioprostheses. Despite the good short- and long-term outcomes after implantation of stentless aortic bioprostheses, their use remains limited owing to the technically demanding implantation techniques. Nevertheless, stentless aortic bioprostheses might be of special benefit in certain indications, where they could be a valuable addition to the surgical armamentarium.

A propensity matched analysis of outcomes and long term survival in stented versus stentless valves

BACKGROUND

To compare the perioperative and long term survival after aortic valve replacement using stentless versus stented valves in a large cohort of patients grouped using propensity score matching.

METHODS

From 1991 to 2012, 4,563 patients underwent aortic valve replacement with stentless and stented valves at our institution. Propensity score matching identified 444 pairs using 13 independent variables: incidence of operation, smoking status, renal failure, hypertension, diabetes, peripheral vascular disease, cerebrovascular disease, chronic lung disease, ejection fraction, gender, age, valve status, and use of coronary artery bypass graft. Data were collected from our Society of Thoracic Surgeons database and the Social Security Death Index. Groups were compared using univariate and Kaplan-Meier analysis.

RESULTS

The two groups demonstrated no significant differences for the 13 matching variables and the majority of 30-day outcomes (p > 0.05). The stented valve group showed a higher incidence of postoperative bleeding (3.6% vs 1.1%, p = 0.015), but a lower incidence of stroke (0.9% vs. 2.9%, p = 0.028). One, five, and 10-year survival was 95.0, 80.7, and 52.8% for stented and 93.2, 80.5, and 51.3% for stentless valves. Overall survival did not differ significantly between the two groups (p = 0.641).

CONCLUSIONS

Stentless and stented valves had identical 30-day outcomes except for a higher postoperative incidence of bleeding and a lower incidence of stroke in the stented group. There was no significant difference in long term survival between valve types. Both valves may be used for aortic valve replacement with low morbidity and excellent long term survival.

An Early Canadian Experience With the Correx Automated Coring and Apical Connector Device for Aortic Valve Bypass

OBJECTIVE

Aortic valve replacement is the standard of care for severe, symptomatic aortic valve stenosis (AS); however, anatomy or pre-existing comorbidities may preclude conventional or alternative transcatheter approaches. Aortic valve bypass (AVB) may be performed as a salvage procedure for the relief of symptomatic aortic stenosis in patients who are not suitable candidates for aortic valve replacement.

METHODS

At our institution, seven patients underwent AVB using the Correx automated coring and apical connector system. All patients had severe AS with New York Heart Association functional class 3 symptoms and were not candidates for conventional or transcatheter approaches. Via a left anterolateral thoracotomy to access the descending aorta and left ventricular apex, we used the Correx system (Correx, Waltham, MA USA) to anastomose a valve conduit to the left ventricular apex proximally and the descending aorta distally. Three patients required cardiopulmonary bypass.

RESULTS

In all seven patients, the automated coring and apical connector was successfully deployed. There were two in-hospital deaths in this series. Immediately postoperatively and at 3 months, there was a significant reduction in mean and peak valve gradients, and all surviving patients performed at New York Heart Association functional class 1.

CONCLUSIONS

Aortic valve bypass seems to be an acceptable alternative for the treatment of severe AS in high-risk patients who are not candidates for aortic valve replacement. The Correx automated system may improve the clinical applicability and surgical reproducibility of AVB in appropriately selected patients in which conventional or transcatheter aortic valve replacement is not a feasible options.

Aortic valve reconstruction with use of pericardial leaflets in adults with bicuspid aortic valve disease: early and midterm outcomes

In this study, we retrospectively analyzed the outcomes of adults with bicuspid aortic valve (BAV) disease who underwent aortic valve reconstructive surgery (AVRS), consisting of replacement of the diseased BAV with 2 or 3 pericardial leaflets plus fixation of the sinotubular junction for accurate and constant leaflet coaptation. From December 2007 through April 2013, 135 consecutive patients (mean age, 49.2 ± 13.1 yr; 73.3% men) with symptomatic BAV disease underwent AVRS. Raphe was observed in 84 patients (62.2%), and the remaining 51 patients had pure BAV without raphe. A total of 122 patients (90.4%) underwent 3-leaflet reconstruction, and 13 (9.6%) underwent 2-leaflet reconstruction. Concomitant aortic wrapping with an artificial graft was performed in 63 patients (46.7%). There were no in-hospital deaths and 2 late deaths (1.5%); 6 patients (4.4%) needed valve-related reoperation. The 5-year cumulative survival rate was 98% ± 1.5%, and freedom from valve-related reoperation at 5 years was 92.7% ± 3.6%. In the last available echocardiograms, aortic regurgitation was absent or trivial in 116 patients (85.9%), mild in 16 (11.9%), moderate in 2 (1.5%), and severe in one (0.7%). The mean aortic valve gradient was 10.2 ± 4.5 mmHg, and the mean aortic valve orifice area index was 1.3 ± 0.3 cm(2)/m(2). The 3-leaflet technique resulted in lower valve gradients and greater valve areas than did the 2-leaflet technique. Thus, in patients with BAV, AVRS yielded satisfactory early and midterm results with low mortality rates and low reoperation risk after the initial procedure.

Leaflet replacement for aortic stenosis using the 3f stentless aortic bioprosthesis: midterm results

BACKGROUND

The 3f aortic bioprosthesis is a stentless valve resembling the native aortic valve. It has been postulated that improved hemodynamic performance with this prosthesis may translate into superior durability. We hereby report the midterm results using this valve substitute.

METHODS

Fifty patients with severe aortic stenosis received the 3f aortic bioprosthesis between 2002 and 2004 in our unit. Clinical outcomes, effective orifice area, mean gradients, and ejection fraction were evaluated at discharge, at 6 and 12 months, and yearly thereafter.

RESULTS

Mean follow-up was 52 ± 10 months and was complete in 96% of surviving patients. Hemodynamic performance of the 3f valve was satisfactory for substitutes in the range of 25 mm and 27 mm; smaller valve substitutes showed unfavorable hemodynamic performance with mean gradients of 18 ± 7 mm Hg for 21-mm prosthesis, and 14 ± 5 mm Hg for 23-mm prosthesis. Consequently, the regression of left ventricular hypertrophy was incomplete. Late mortality included 10 patients (valve-related in 1, cardiac-related in 3) for a survival of 77% ± 3% at 4 years. Four patients required reoperation owing to endocarditis in 2 and paravalvular leak in other 2. Freedom from reoperation was 93% at 4 years. Six patients experienced 9 neurologic events, accounting for 82% freedom from neurologic events.

CONCLUSIONS

Its unique design makes the 3f aortic bioprosthesis less complex to implant than conventional stentless valves, as only a single suture line is necessary. The hemodynamic profile and clinical performance of the prosthesis are inconsistent with the established stentless valves, especially with regard to higher incidence of neurologic complications seen during the follow-up.

Stentless aortic valve replacement: an update

Although porcine aortic valves or pericardial tissue mounted on a stent have made implantation techniques easier, these valves sacrifice orifice area and increase stress at the attachment of the stent, which causes primary tissue failure. Optimizing hemodynamics to prevent patient–prosthetic mismatch and improve durability, stentless bioprostheses use was revived in the early 1990s. The purpose of this review is to provide a current overview of stentless valves in the aortic position. Retrospective and prospective randomized controlled studies showed similar operative mortality and morbidity in stented and stentless aortic valve replacement (AVR), though stentless AVR required longer cross-clamp and cardiopulmonary bypass time. Several cohort studies showed improved survival after stentless AVR, probably due to better hemodynamic performance and earlier left ventricular (LV) mass regression compared with stented AVR. However, there was a bias of operation age and nonrandomization. A randomized trial supported an improved 8-year survival of patients with the Freestyle or Toronto valves compared with Carpentier–Edwards porcine valves. On the contrary, another randomized study did not show improved clinical outcomes up to 12 years. Freedom from reoperation at 12 years in Toronto stentless porcine valves ranged from 69% to 75%, which is much lower than for Carpentier–Edwards Perimount valves. Cusp tear with consequent aortic regurgitation was the most common cause of structural valve deterioration. Cryolife O’Brien valves also have shorter durability compared with stent valves. Actuarial freedom from reoperation was 44% at 10 years. Early prosthetic valve failure was also reported in patients who underwent root replacement with Shelhigh stentless composite grafts. There was no level I or IIa evidence of more effective orifice area, mean pressure gradient, LV mass regression, surgical risk, durability, and late outcomes in stentless bioprostheses. There is no general recommendation to prefer stentless bioprostheses in all patients. For new-generation pericardial stentless valves, follow-up over 15 years is necessary to compare the excellent results of stented valves such as the Carpentier–Edwards Perimount and Hancock II valves.

Does stentless aortic valve implantation increase perioperative risk? A critical appraisal of the literature and risk of bias analysis

Stentless aortic valve replacement has potential benefits in terms of valve hemodynamics and clinical outcomes, although these may be offset by greater technical complexity of implantation with longer cardiopulmonary bypass and cross-clamp times compared with stented valves. Meta-analyses of the small number of published randomized trials have been limited by their lack of critical synthesis of the literature, including evaluation of the Risk of Bias. Our objective was to determine whether stentless aortic valves increase perioperative risk of mortality. We also examined secondary clinical outcomes of neurological, renal and respiratory complications as well as hemodynamic changes reported by studies following implantation of the two types of aortic prosthesis. The methodology used to answer this question was a rigorous meta-analysis of randomized controlled trials, using bias-assessment techniques designed to address limitations of conventional meta-analysis. Our findings show that many of the existing randomized trials have a high or uncertain risk of bias. Analysis of studies with low risk of bias reveals that stentless valves do not increase perioperative risk in terms of 30-day mortality and morbidity though neither do they exhibit benefits in hemodynamics or clinical outcomes compared with stented valves. Larger, more stringent randomized studies would be required to identify any robust clinical difference.

Stentless versus Stented Bioprosthetic Aortic Valves: A Systematic Review and Meta-Analysis of Controlled Trials

Objective

This meta-analysis sought to determine whether stentless bioprosthetic valves improve clinical and resource outcomes compared with stented valves in patients undergoing aortic valve replacement.

Methods

A comprehensive search was undertaken to identify all randomized and nonrandomized controlled trials comparing stentless to stented bioprosthetic valves in patients undergoing aortic valve replacement available up to March 2008. The primary outcomes were clinical and resource outcomes in randomized controlled trial (RCT). Secondary outcomes clinical and resource outcomes in nonrandomized controlled trial (non-RCT). Odds ratios (OR), weighted mean differences (WMD), or standardized mean differences and their 95% confidence intervals (CI) were analyzed as appropriate.

Results

Seventeen RCTs published in 23 articles involving 1317 patients, and 14 non-RCTs published in 18 articles involving 2485 patients were included in the meta-analysis. For the primary analysis of randomized trials, mortality for stentless versus stented valve groups did not differ at 30 days (OR 1.36, 95% CI 0.68–2.72), 1 year (OR 1.01, 95% CI 0.55–1.85), or 2 to 10 years follow-up (OR 0.82, 95% CI 0.50–1.33). Aggregate event rates for all-cause mortality at 30 days were 3.7% versus 2.9%, at 1 year were 5.5% versus 5.9% and at 2 to 10 years were 17% versus 19% for stentless versus stented valve groups, respectively. Stroke or neurologic complications did not differ between stentless (3.6%) and stented (4.0%) valve groups. Risk of prosthesis-patient mismatch was numerically lower in the stentless group (11.0% vs. 31.3%, OR 0.30, 95% CI 0.05–1.66), but this parameter was reported in few trials and did not reach statistical significance. Effective orifice area index was significantly greater for stentless aortic valve compared with stented valves at 30 days (WMD 0.12 cm2/m2), at 2 to 6 months (WMD 0.15 cm2/m2), and at 1 year (WMD 0.26 cm2/m2). Mean gradient at 1 month was significantly lower in the stentless valve group (WMD −6 mm Hg), at 2 to 6 month follow-up (WMD −4 mm Hg,), at 1 year follow-up (WMD −3 mm Hg) and up to 3 year follow-up (WMD −3 mm Hg) compared with the stented valve group. Although the left ventricular mass index was generally lower in the stentless group versus the stented valve group, the aggregate estimates of mean difference did not reach significance during any time period of follow-up (1 month, 2–6 months, 1 year, and 8 years).

Conclusions

Evidence from randomized trials shows that subcoronary stentless aortic valves improve hemodynamic parameters of effective orifice area index, mean gradient, and peak gradient over the short and long term. These improvements have not led to proven impact on patient morbidity, mortality, and resource-related outcomes; however, few trials reported on clinical outcomes beyond 1 year and definitive conclusions are not possible until sufficient evidence addresses longer-term effects.