The subcoronary Toronto stentless versus supra-annular Perimount stented replacement aortic valve: Early clinical and hemodynamic results of a randomized comparison in 160 patients

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.

Stented versus Stentless Aortic Valve Replacement in Patients with Small Aortic Root

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.

Surgery for Young Adults With Aortic Valve Disease not Amenable to Repair

Aortic valve replacement is the gold standard for the management of patients with severe aortic stenosis or mixed pathology that is not amenable to repair according to currently available guidelines. Such a simplified approach may be suitable for many patients, but it is far from ideal for young adults considering emerging evidence demonstrating that conventional valve replacement in this cohort of patients is associated with inferior long-term survival when compared to the general population. Moreover; the utilisation of mechanical and bioprosthetic valves can significantly impact on quality and is linked to increased rates of morbidities. Other available options such as stentless valve, homografts, valve reconstruction and Ross operation can be an appealing alternative to conventional valve replacement. Young patients should be fully informed about all the options available - shared decision making is now part of modern informed consent. This can be achieved when referring physicians have a better understanding of the short and long term outcomes associated with every intervention, in terms of survival and quality of life. This review presents up to date evidence for available surgical options for young adults with aortic stenosis and mixed disease not amenable to repair.

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 comparison of two forms of the continuity equation in the Trifecta bovine pericardial aortic valve

AIM

To compare the classical and simplified form of the continuity equation in small Trifecta valves.

METHODS

This is a retrospective analysis of post-operative echocardiograms performed for clinical reasons after implantation of Trifecta bioprosthetic valves.

RESULTS

There were 60 patients aged 74 (range 38-89) years. For the valves of size 19, 21 and 23mm, the mean gradient was 11.3, 10.7 and 9.7mmHg, respectively. The effective orifice areas by the classical form of the continuity equation were 1.4, 1.7 and 1.9cm(2), respectively. There was a good correlation between the two forms of the continuity equation, but they were significantly different using a t-test (P<0.00001). Results using the classical form were a mean 0.11 (s.d. 0.18)cm(2) larger than those using the simple formula.

CONCLUSION

Haemodynamic function of the Trifecta valve in the small aortic root is good. There are significant differences between the classical and simplified forms of the continuity equation.

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.

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.

Choice of prosthetic heart valve in adults an update

In the last 7 years, more data have reconfirmed that patients' comorbid conditions are very important factors determining patient outcomes. Prosthetic heart valves (PHVs) that require aortic root replacement in the absence of aortic root disease are associated with poorer outcomes. For the vast majority of patients, the choice of PHV is between a mechanical valve and a stented bioprosthesis. The choice is largely dependent upon the age of the patient at the time of PHV implantation and on which complication the patient wants to avoid: specifically, anticoagulation therapy and its complications with the mechanical valve, and structural valve deterioration with a bioprosthesis. Data on the pros and cons of the choices and exceptions to the rules are discussed, and a new algorithm is developed.

Stentless versus Stented Bioprosthetic Aortic Valves

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.

Aortic valve replacement with the Sorin Pericarbon Freedom stentless prosthesis: 7 years' experience in 130 patients

OBJECTIVES

Aortic stentless pericardial valves were introduced into clinical practice to combine properties of both stentless and pericardial prostheses. The aim of this single-center retrospective study was to assess midterm clinical and hemodynamic results of aortic valve replacement with the Sorin Pericarbon Freedom stentless bioprosthesis.

METHODS

From July 1999 through November 2005, 130 consecutive patients (73 [56.1%] male patients) underwent aortic valve replacement with the Sorin Pericarbon Freedom bioprosthesis at our institution. Mean age was 76 +/- 5 years (range, 42-86 years), and associated procedures were performed in 50 (38.4%) patients; of these, 41 were coronary artery bypass grafts. Surgical intervention under urgent/emergency conditions and reoperations were performed in 18 (13.8%) and 7 (5.3%) patients, respectively. Mean crossclamp and cardiopulmonary bypass times were 82 +/- 24 and 125 +/- 40 minutes, respectively. All patients underwent clinical and echocardiographic follow-up (100% complete), and the total cumulative follow-up was 324 patient/years (mean, 2.5 +/- 1.8; range, 6 months-7 years).

RESULTS

Overall hospital mortality was 8.4%. Overall patient survival was 63% +/- 6% and 50% +/- 10% at 5 and 7 years, respectively. Late deaths occurred in 23 patients, and 6 of them were valve related (1.8% patient/years). Freedom from valve-related death and reoperation was 91% +/- 4% and 94% +/- 4%, respectively, at 7 years. No structural valve deterioration was observed. Endocarditis, thromboembolism, and hemorrhagic complications occurred in 2 (0.6% patient/years), 1 (0.3% patient/years), and 1 (0.3% patient/years) patients, respectively. Mean transprosthetic gradients for valve sizes 23, 25, and 27 were 12.1 +/- 3.8, 10.8 +/- 3.8, and 9 +/- 3.1 mm Hg, respectively.

CONCLUSIONS

The Sorin Pericarbon Freedom stentless bioprosthesis provides good early and midterm results in terms of hemodynamic performance, survival, and freedom from valve-related complications.

A randomized comparison of the Cryolife O'Brien and Toronto stentless replacement aortic valves

OBJECTIVE

A composite stentless valve might be less obstructive than a preparation incorporating the porcine right coronary muscle bar. The aim of this study was to compare early hemodynamic function in a prospective series of 78 patients randomized to receive either a Toronto or Cryolife O'Brien stentless valve.

METHODS

Echocardiography was performed early after surgery, between 3 and 6 months, and at 1 year after surgery.

RESULTS

The groups were matched demographically. The Cryolife O'Brien valve was significantly less obstructive in terms of effective orifice area (1.81 vs 1.30 cm2; P < .0001), mean pressure difference (7.1 vs 11.7 mm Hg; P < .0001), and peak velocity (1.7 vs 2.2 m/s) assessed at 1 year (P = .001). Bypass time was 91 (SD 22) minutes for the Cryolife O'Brien compared with 125 (SD 22) minutes (P < .0001) for the Toronto. There was a higher incidence of paraprosthetic regurgitation in the Cryolife O'Brien valve (16.7% vs 3.2%). Mortality and clinical events were similar.

CONCLUSION

The composite valve was less obstructive than the porcine valve, suggesting that stentless valves cannot be considered as a homogeneous class.

Stentless valves for aortic valve replacement: where do we stand?

PURPOSE OF REVIEW

Following more than a decade's experience with stentless valves and the development of better profiled stented valves, the article discusses the advantages of stentless valves regarding hemodynamic performance, left ventricular mass regression, durability and survival.

RECENT FINDINGS

Recent studies show that stentless valves remain hemodynamically superior compared with modern porcine stented valves. This superiority is, however, rarely reported in comparison with modern pericardial stented valves. In general, patient-prosthesis mismatch is less frequent in stentless vs. stented valves. Recent randomized trials comparing stentless valves and modern stented valves show equivalent left ventricular mass regression at 1 year. At 10 years, stentless valve durability is excellent and comparable with that of stented valves. Recent comparative studies do not confirm the previously reported midterm survival advantages of stentless valves.

SUMMARY

Improvement of stented valves has significantly reduced the hemodynamic differences between them and their stentless counterpart. Patients with small aortic annulus, however, should benefit from a stentless valve due to the better expected gradients and lower risk of patient-prosthesis mismatch. Midterm results suggest equivalent durability and survival for both prosthesis types but additional and longer-term trials are necessary to confirm these results.