Randomized Comparison of Stentless Versus Stented Valves for Aortic Stenosis

Interventional versus Surgical Treatment of Degenerated Freestyle Prosthesis

BACKGROUND

 Bioprosthetic stentless aortic valves may degenerate over time and will require replacement. This study aimed to evaluate early- and mid-term outcomes after isolated surgical redo aortic valve replacement (redo-SAVR) and transcatheter valve-in-valve implantation (TAVI-VIV) for degenerated stentless Freestyle bioprostheses.

METHODS

 We reviewed records of 56 patients at a single center. Overall, 37 patients (66.1%) received TAVI-VIV and 19 (33.9%) received redo-SAVR.

RESULTS

 Thirty-day survival was similar in both groups (100%). One-year survival was comparable between groups (97.3% in TAVI-VIV and 100% in redo-SAVR, p = 1.0). The difference in mid-term survival after adjusting for age and EuroScore II was not significant (p = 0.41). The incidence of pacemaker implantation after TAVI-VIV was higher than after redo-SAVR (19.4% vs. 0%, p = 0.08).

CONCLUSION

 The 30-day and 1-year survival rates after both procedures were outstanding, irrespective of baseline characteristics. Isolated redo-SAVR should be favored in young patients, as the pacemaker implantation rate is lower. TAVI-VIV for degenerated Freestyle prosthesis can be a method of choice in elderly patients and those with high operative risk.

Aortic valve neocuspidization using the Ozaki technique: A meta-analysis of reconstructed patient-level data

BACKGROUND

Aortic valve neocuspidization using the Ozaki technique has shown promising results both in adults and children.

METHODS

A systematic search of the PubMed and Cochrane databases was performed up to November 13, 2021. Individual patient data were reconstructed and analyzed from the Kaplan-Meier curves of all eligible studies for time-to-event outcomes.

RESULTS

We included a total of 22 studies reporting on 1,891 patients that underwent Ozaki reconstruction. Mean age at the time of surgery was 43.2 ± 24.5 years (65 ± 12.3 years for adult patients and 12.3 ± 3.8 years for pediatric patients). The most common indication was aortic stenosis (46.4%, 95% CI 34.1-58.6). Mean cross-clamp and cardiopulmonary bypass duration were 106.8 ± 24.8 minutes and 135.2 ± 35.1 minutes, respectively. Permanent pacemaker was implanted in 0.7% (95% CI 0.4-1.2) of the patients. At discharge, mean effective orifice area was 2.1 ± 0.5 cm²/m². At latest follow-up, peak gradient was 15.7 ± 7.4 mm Hg and only 0.25% (95% CI 0-2.3) had moderate aortic insufficiency. In-hospital mortality was 0.7% (95% CI 0.1-1.7). Late mortality was 1.9% during a mean follow-up of 38.1 ± 23.8 months. One-year, 3-year, and 5-year freedom from reoperation rates were 98.0 %, 97.0 % and 96.5%, respectively. More than half of the reoperations were due to infective endocarditis (51.5%, 95% CI 18.3-84.0). In our cohort, the risk of endocarditis per patient per year was 0.5%.

CONCLUSIONS

The midterm outcomes of the Ozaki procedure are excellent in terms of hemodynamics, survival, and freedom from reoperation. Acquiring long-term follow-up will help solidify this technique in the cardiac surgery armamentarium.

Aortic valve neocuspidisation using xenologous pericardium versus bioprosthetic valve replacement

BACKGROUND

Surgical aortic valve replacement (SAVR) for aortic valve stenosis (AS) patients with small aortic root is associated with a higher rate of prosthesis-patient mismatch and suboptimal clinical outcomes. Aortic valve neocuspidisation using xenologous pericardium (xAVNeo) has shown favorable hemodynamic performance. The aim was to compare 6-year clinical outcomes of xAVNeo with SAVR.

METHODS

Between 2003-2018, 412 patients with severe AS and small aortic root received either xAVNeo (N=114) or bioprosthesis (N=298). After propensity matching, the cohort included 222 patients. The primary endpoints were early-, 6-year mortality and freedom from reoperation. Mean follow-up averaged 3.4±3.1 years and was 95% complete.

RESULTS

Early mortality was 8.1% for the SAVR group vs 9.9% for the xAVNeo group, OR 1.25 [CI95% 0.51-2.89]. The estimated survival probabilities at 6 years for the SAVR and xAVNeo cohorts were 89.9% and 88.8%, respectively, OR 1.07 [0.49-2.34]. Progressive degeneration of the neo-cusps resulted in mean gradients increase from 6.1±2.3 mmHg to 22.7±11.5 mmHg ( p<0.0001 ); cusp sclerosis was the most common indication for reoperation in the xAVNeo group with a linearised rate of 1.92% vs. 0.26% per patient-year, rate ratio = 7.41 [CI95% 0.95-333.7]. The freedom from reoperation was 84.8% at 6 years, inferior to that of the SAVR group (100%).

CONCLUSIONS

Early clinical outcome and 6-year survival following xAVNeo and SAVR was comparable. However, xAVNeo using bovine pericardium was associated with a higher rate of structural valve deterioration and inferior freedom from reoperation when compared to SAVR.

The evaluation of annuloplasty in bicuspid aortic valve repair using cardiac magnetic resonance

Background

The incompetent bicuspid aortic valve (BAV) can be replaced or repaired using various surgical techniques. This study sought to assess the efficacy of external annuloplasty and postoperative reverse remodelling using cardiac magnetic resonance (CMR) and compare the results of external and subcommissural annuloplasty.

Methods

Out of a total of 200 BAV repair performed between 2004 and 2018, 21 consecutive patients (median age 54 years) with regurgitation requiring valve repair with annuloplasty without concomitant aortic root surgery were prospectively referred for CMR and transthoracic echocardiography (TTE) one year after the operation. Two aortic annulus stabilization techniques were used: external, circumferential annuloplasty (EA), and subcommissural annuloplasty (SCA).

Results

11 patients received EA and 10 patients were treated using SCA. There was no in-hospital mortality and all patients survived the follow-up period (median: 12.6 months (first quartile: 6.6; third quartile: 14.1). CMR showed strong correlation between postoperative aortic recurrent regurgitant fraction and left ventricular end-diastolic volume (r = 0.62; p = 0.003) as well as left ventricular ejection fraction (r = -0.53; p = 0.01). Patients treated with EA as compared with SCA had larger anatomic aortic valve area measured by CMR (3.5 (2.5; 4.0) vs. 2.5 cm² (2.0; 3.4); p = 0.04). In both EA and SCA group, aortic valve area below 3.5 cm² correlated with no regurgitation recurrency. EA (vs. SCA) was associated with lower peak transvalvular aortic gradients (10 (6; 17) vs. 21 mmHg (15; 27); p = 0.04).

Conclusions

The repair of the bicuspid aortic valve provides significant postoperative reverse remodelling, provided no recurrent regurgitation and durable reduction annuloplasty can be achieved. EA is associated with lower transvalvular gradients and higher aortic valve area assessed by CMR, compared to SCA.

Structural valve deterioration and mode of failure of stentless bioprosthetic valves

BACKGROUND

Aortic stentless bioprosthetic valve (SLBPV), either porcine or pericardial, minimizes transvalvular gradient and favors regression of left ventricular hypertrophy. The drawback consists of longer time for suturing. While structural valve deterioration (SVD) in stented porcine and pericardial BPVs has been extensively investigated, less information is available on SLBPVs.

MATERIAL AND METHODS

We studied 82 SLBPVs explants, either porcine (Toronto SPV, [St. Jude Medical, MN, USA], CryolifeO'Brien Model 300 and CryoLife-O'Brien [Cryolife International, GA, USA], BioCor PVS [St. Jude Medical, MN, USA] Prima and Prima Plus [Edwards Lifesciences Corp. One Edwards Way, CA, formerly Baxter Inc, CA, USA]) or pericardial ([Pericarbon Freedom and Freedom Solo [Sorin-Biomedica, S.p.A., Saluggia, Italy]).

RESULTS

By excluding cases with leak and endocarditis, we focused the investigation on 46 SLBPVs, which failed because of SVD. Gender was male in 29 (63%). Mean age of patients at time of implant was 59.8 years. Postoperative time of SVD was 115.0 months for porcine and 79.0 months for pericardial SLBPVs. Dysfunction requiring reoperation was mainly incompetence for porcine and stenosis for pericardial SLBPVs. Even pinpoint mineralization at the commissures resulted in sudden cusp tearing and incompetence. Cuspal atheromasia accounted for cusp tearing even in the absence of calcification. Mineralization showed progression with time in pericardial but not in porcine SLBPVs.

CONCLUSIONS

Tissue mineralization remains the nightmare also of SLBPVs, with the peculiar features of pinpoint calcific deposits at commissures, tearing and abrupt incompetence in porcine SLBPVs and of massive cuspal mineralization and stenosis in pericardial SLBPVs.

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.

Morphometrical and biomechanical analyses of a stentless bioprosthetic valve: an implication to avoid potential primary tissue failure

OBJECTIVES

Stentless bioprosthetic valves provide hemodynamic advantages over stented valves as well as excellent durability. However, some primary tissue failures in bioprostheses have been reported. This study was conducted to evaluate the morphometrical and biomechanical properties of the stentless Medtronic Freestyle™ aortic root bioprosthesis, to identify any arising problem areas, and to speculate on a potential solution.

METHODS

The three-dimensional heterogeneity of the stentless bioprosthesis wall was investigated using computed tomography. The ascending aorta and the right, left, and non-coronary sinuses of Valsalva were resected and examined by an indentation test to evaluate their biomechanical properties.

RESULTS

The non-coronary sinus of Valsalva was significantly thinner than the right sinus of Valsalva (p < 0.01). Young's modulus, calculated as an indicator of elasticity, was significantly greater at the non-coronary sinus of Valsalva (430.7 ± 374.2 kPa) than at either the left (190.6 ± 70.6 kPa, p < 0.01) or right sinuses of Valsalva (240.0 ± 56.5 kPa, p < 0.05).

CONCLUSIONS

Based on the morphometrical and biomechanical analyses of the stentless bioprosthesis, we demonstrated that there are differences in wall thickness and elasticity between each sinus of Valsalva. These differences suggest that the non-coronary sinus of Valsalva is the most vulnerable and at greater risk of tissue failure. The exclusion of the non-coronary sinus of Valsalva may be beneficial to mitigate the long-term risks of tissue failure in the stentless bioprosthesis.

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.

Early hemodynamics and clinical outcomes of isolated aortic valve replacement with stentless or transcatheter valve in intermediate-risk patients

OBJECTIVE

Stentless aortic valves have been developed to overcome obstructive limitations associated with stented bioprostheses. The aim of the current multi-institutional study was to compare hemodynamics of transcatheter (TAVR) and the Freedom SOLO Stentless (FS) valve in an intermediate risk population undergoing surgical aortic valve replacement.

METHODS

From 2010 to 2014, 420 consecutive patients underwent isolated surgical aortic valve replacement with FS and 375 patients underwent TAVR. Only patients with intermediate operative risk (Society of Thoracic Surgeons score 4-10) and small aortic annulus (≤23 mm) were included. After a propensity matched analysis 142 patients in each group were selected. Thirty-day postoperative clinical and echocardiographic parameters were evaluated.

RESULTS

Mean prosthesis diameter was 22.2 ± 0.9 mm for FS and 22.4 ± 1.0 mm for TAVR. In-hospital mortality was 2.1% for FS and 6.3% for TAVR (P = .02). Postoperative FS peak gradients were 19.1 ± 9.6 mm Hg (mean 10.8 ± 5.9 mm Hg); TAVR peak gradients were 20.2 ± 9.5 mm Hg (mean 10.7 ± 6.9 mm Hg) P = .57 (P = .88). Postoperative effective orifice area was 1.93 ± 0.52 cm² for FS and 1.83 ± 0.3 cm² for TAVR (P = .65). There was no prostheses-patient mismatch in either group. Postoperative grade 2-3 paravalvular leak was present in 3.5% for TAVR and 0.7% for FS. Postoperative permanent pacemaker implant rate was 12% for TAVR and only 1 case (0.7%) in the FS group (P < .001).

CONCLUSIONS

In patients with small aortic annulus and intermediate risk, both FS and TAVR demonstrated similar excellent hemodynamic performance. TAVR demonstrated greater mortality and rates of pacemaker insertion. Further studies are warranted to validate TAVR indications in this subset of patients.

Biomechanical Behavior of Bioprosthetic Heart Valve Heterograft Tissues: Characterization, Simulation, and Performance

The use of replacement heart valves continues to grow due to the increased prevalence of valvular heart disease resulting from an ageing population. Since bioprosthetic heart valves (BHVs) continue to be the preferred replacement valve, there continues to be a strong need to develop better and more reliable BHVs through and improved the general understanding of BHV failure mechanisms. The major technological hurdle for the lifespan of the BHV implant continues to be the durability of the constituent leaflet biomaterials, which if improved can lead to substantial clinical impact. In order to develop improved solutions for BHV biomaterials, it is critical to have a better understanding of the inherent biomechanical behaviors of the leaflet biomaterials, including chemical treatment technologies, the impact of repetitive mechanical loading, and the inherent failure modes. This review seeks to provide a comprehensive overview of these issues, with a focus on developing insight on the mechanisms of BHV function and failure. Additionally, this review provides a detailed summary of the computational biomechanical simulations that have been used to inform and develop a higher level of understanding of BHV tissues and their failure modes. Collectively, this information should serve as a tool not only to infer reliable and dependable prosthesis function, but also to instigate and facilitate the design of future bioprosthetic valves and clinically impact cardiology.

Full-root aortic valve replacement with stentless xenograft achieves superior regression of left ventricular hypertrophy compared to pericardial stented aortic valves

BACKGROUND

Full-root aortic valve replacement with stentless xenografts has potentially superior hemodynamic performance compared to stented valves. However, a number of cardiac surgeons are reluctant to transform a classical stented aortic valve replacement into a technically more demanding full-root stentless aortic valve replacement. Here we describe our technique of full-root stentless aortic xenograft implantation and compare the early clinical and midterm hemodynamic outcomes to those after aortic valve replacement with stented valves.

METHODS

We retrospectively compared the pre-operative characteristics of 180 consecutive patients who underwent full-root replacement with stentless aortic xenografts with those of 80 patients undergoing aortic valve replacement with stented valves. In subgroups presenting with aortic stenosis, we further analyzed the intra-operative data, early postoperative outcomes and mid-term regression of left ventricular mass index.

RESULTS

Patients in the stentless group were younger (62.6 ± 13 vs. 70.3 ± 11.8 years, p < 0.0001) but had a higher Euroscore (9.14 ± 3.39 vs.6.83 ± 2.54, p < 0.0001) than those in the stented group. In the subgroups operated for aortic stenosis, the ischemic (84.3 ± 9.8 vs. 62.3 ± 9.4 min, p < 0.0001) and operative times (246.3 ± 53.6 vs. 191.7 ± 53.2 min, p < 0.0001) were longer for stentless versus stented valve implantation. Nevertheless, early mortality (0% vs. 3%, p < 0.25), re-exploration for bleeding (0% vs. 3%, p < 0.25) and stroke (1.8% vs. 3%, p < 0.77) did not differ between stentless and stented groups. One year after the operation, the mean transvalvular gradient was lower in the stentless versus stented group (5.8 ± 2.9 vs. 13.9 ± 5.3 mmHg, p < 0.0001), associated with a significant regression of the left ventricular mass index in the stentless (p < 0.0001) but not in the stented group (p = 0.2).

CONCLUSION

Our data support that full-root stentless aortic valve replacement can be performed without adversely affecting the early morbidity or mortality in patients operated on for aortic valve stenosis provided that the coronary ostia are not heavily calcified. The additional time necessary for the full-root stentless compared to the classical stented aortic valve replacement is therefore not detrimental to the early clinical outcomes and is largely rewarded in patients with aortic stenosis by lower transvalvular gradients at mid-term and a better regression of their left ventricular mass index.

A critical review of hemodynamic changes and left ventricular remodeling after surgical aortic valve replacement and percutaneous aortic valve replacement

The introduction of transcatheter aortic valve replacement (TAVR) in clinical practice has widened options for symptomatic patients at high surgical risk; however, it is not known whether TAVR has equivalent or prolonged benefits in terms of left ventricular (LV) remodeling.

METHODS

To explore the relative hemodynamic benefits and postoperative LV remodeling associated with TAVR and surgical aortic valve replacement (SAVR), we performed a critical review of the available literature. A total of 67 studies were included in this systematic review.

RESULTS

There is at least equivalent if not slightly superior hemodynamic performance of TAVR over SAVR, and TAVR showed lower prosthesis-patient mismatch compared with SAVR. However, LV mass appears to regress to a greater degree after SAVR compared with TAVR. Aortic regurgitation, paravalvular in particular, is more common after TAVR than SAVR, although it is rarely more than moderate in severity. Improvements in diastolic function and mitral regurgitation are reported in only a handful of studies each and could not be compared across prosthesis types.

CONCLUSIONS

The published data support the hemodynamic comparability of SAVR and TAVR, with the higher incidence of prosthesis-patient mismatch in SAVR offset by higher incidence of paravalvular leak in TAVR. These results highlight the need for further studies focusing on hemodynamic changes after valve therapy.

The freestyle aortic bioprosthesis: a systematic review

BACKGROUND

The Medtronic Freestyle bioprosthesis (FSB) provides an alternative to other prostheses for both aortic valve and aortic root surgery. This paper is a systematic review of the post-operative outcomes in patients with aortic valve and/or aortic root disease following FSB implantation.

METHODS

Electronic databases were searched for primary analysis, prospective randomised studies comparing the FSB with an alternative aortic prosthesis were included. Additionally, case series that included data for at least 100 individual operated patients were used for secondary analysis.

RESULTS

Among three identified randomised studies, 199 FSB cases were compared with homografts, and stented and an alternative stentless bioprosthesis. The FSB showed comparable hospital mortality (4.5% vs. 5.3%) and eight-year actuarial survival (80±5.0% versus 77±6.0%) with the homograft (respectively) and comparable reduction in left ventricular mass index relative to other prosthesis types. Over 6000 individual patients were included in the selected 15 case series. Weighted mean operative mortality, neurological event rate and five-year actuarial survival was 5.2%, 5.5% and 77.8%, respectively.

CONCLUSION

The FSB performed comparably against alternative prostheses regarding in-hospital mortality, long-term survival and reduction in left ventricular mass index. Included case series demonstrated robust post-operative outcomes in both the short and long term.

Anesthetic management of a patient with obstructive prosthetic aortic valve dysfunction: a case report

We present a 55-year-old female patient who underwent burr-hole drainage due to chronic subdural hematoma, with obstructive prosthetic aortic valve dysfunction. Anesthetic management of a patient with severe obstructive prosthetic aortic valve dysfunction can be challenging. Similar considerations should be given to patients with aortic stenosis with an additional emphasis on thrombotic complication due to discontinuation of anticoagulation, which may further jeopardize the valve dysfunction. This case emphasizes the importance of a comprehensive understanding of the etiology and hemodynamic consequences of obstructive prosthetic valve dysfunction and the adequacy of anticoagulation for patients undergoing noncardiac surgery even after a successful valve replacement.

Impact of aortic prosthesis-patient mismatch on left ventricular mass regression

Background

Prostheses used for aortic valve replacement may be small in relation to body size, causing prosthesis-patient mismatch and delaying left ventricular mass regression. This study examined the effect of prosthesis-patient mismatch on regression of left ventricular mass after aortic valve replacement.

Methods

We prospectively studied 96 patients undergoing aortic valve replacement between 2007 and 2012. Mean and peak gradients and indexed effective orifice area were measured by transthoracic echocardiography at 3 and 6 months postoperatively. Patient-prosthesis mismatch was defined as indexed effective orifice area ≤0.85 cm2·m−2.

Results

Moderate prosthesis-patient mismatch was present in 25% of patients. There were no significant differences in demographic and operative data between patients with and without prosthesis-patient mismatch. Left ventricular dimensions, posterior wall thickness, transvalvular gradients, and left ventricular mass decreased significantly after aortic valve replacement in both groups. The interventricular septal diameter and left ventricular mass index regression, and left ventricular ejection fraction were better in patients without prosthesis-patient mismatch. There was a significant positive correlation between the postoperative indexed effective orifice area of each valve prosthesis and the rate of left ventricular mass regression.

Conclusions

Prosthesis-patient mismatch leads to higher transprosthetic gradients and impaired left ventricular mass regression. A small-sized valve prosthesis does not necessarily result in prosthesis-patient mismatch, and may be perfectly adequate in patient with small body size.

Secreted Wnt modulators in symptomatic aortic stenosis

Background

Valve calcification and inflammation play key roles in the development of aortic stenosis (AS). The Wnt pathways have been linked to inflammation, bone metabolism, angiogenesis, and heart valve formation. We hypothesized that soluble Wnt modulators may be dysregulated in symptomatic AS.

Methods and Results

We measured circulating levels (n=136) and aortic valve tissue expression (n=16) of the secreted Wnt modulators secreted frizzled related protein-3, dickkopf-1 (DKK-1), and Wnt inhibitory factor-1 (WIF-1) by enzyme immunoassay, immunostaining, and RT-PCR in patients with symptomatic, severe AS and investigated associations with echocardiographic parameters of AS and cardiac function. Finally, we assessed the prognostic value of these Wnt modulators in relation to all-cause mortality (n=35) during long-term follow-up (median 4.6 years; survivors, 4.8 years; nonsurvivors, 1.9 years) in these patients. Our main findings were: (1) serum levels of all Wnt modulators were markedly elevated in patients with symptomatic AS (mean increase 231% to 278%, P<0.001), (2) all Wnt modulators were present in calcified aortic valves but correlated poorly with systemic levels or degree of AS, (3) some modulators (ie, WIF-1) were associated with the degree of myocardial function and valvular calcification, (4) all Wnt modulators, and DKK-1 in particular, predicted long-term mortality in these patients also after adjusting for conventional predictors including NT-proBNP.

Conclusions

Together, these in vivo data support the involvement of Wnt signaling in the development of AS and suggest that circulating Wnt modulators should be further investigated as risk markers in larger AS populations, including patients with asymptomatic disease.

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.

LV reverse remodeling imparted by aortic valve replacement for severe aortic stenosis; is it durable? A cardiovascular MRI study sponsored by the American Heart Association

BACKGROUND

In patients with severe aortic stenosis (AS), long-term data tracking surgically induced effects of afterload reduction on reverse LV remodeling are not available. Echocardiographic data is available short term, but in limited fashion beyond one year. Cardiovascular MRI (CMR) offers the ability to serially track changes in LV metrics with small numbers due to its inherent high spatial resolution and low variability.

HYPOTHESIS

We hypothesize that changes in LV structure and function following aortic valve replacement (AVR) are detectable by CMR and once triggered by AVR, continue for an extended period.

METHODS

Twenty-four patients of which ten (67 ± 12 years, 6 female) with severe, but compensated AS underwent CMR pre-AVR, 6 months, 1 year and up to 4 years post-AVR. 3D LV mass index, volumetrics, LV geometry, and EF were measured.

RESULTS

All patients survived AVR and underwent CMR 4 serial CMR's. LVMI markedly decreased by 6 months (157 ± 42 to 134 ± 32 g/m2, p < 0.005) and continued trending downwards through 4 years (127 ± 32 g/m2). Similarly, EF increased pre to post-AVR (55 ± 22 to 65 ± 11%,(p < 0.05)) and continued trending upwards, remaining stable through years 1-4 (66 ± 11 vs. 65 ± 9%). LVEDVI, initially high pre-AVR, decreased post-AVR (83 ± 30 to 68 ± 11 ml/m2, p < 0.05) trending even lower by year 4 (66 ± 10 ml/m2). LV stroke volume increased rapidly from pre to post-AVR (40 ± 11 to 44 ± 7 ml, p < 0.05) continuing to increase non-significantly through 4 years (49 ± 14 ml) with these LV metrics paralleling improvements in NYHA. However, LVmass/volume, a 3D measure of LV geometry, remained unchanged over 4 years.

CONCLUSION

After initial beneficial effects imparted by AVR in severe AS patients, there are, as expected, marked improvements in LV reverse remodeling. Via CMR, surgically induced benefits to LV structure and function are durable and, unexpectedly express continued, albeit markedly incomplete improvement through 4 years post-AVR concordant with sustained improved clinical status. This supports down-regulation of both mRNA and MMP activity acutely with robust suppression long term.

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.

Effect of candesartan treatment on left ventricular remodeling after aortic valve replacement for aortic stenosis

In hypertension, angiotensin receptor blockers can augment regression of left ventricular (LV) hypertrophy. It is not known whether this also is the case after aortic valve replacement (AVR) for severe aortic stenosis (AS). To test the hypothesis that treatment with candesartan in addition to conventional treatment is able to augment LV and left atrial (LA) reverse remodeling in patients with AS undergoing AVR, we studied 114 patients scheduled for AVR. Patients were randomized to treatment with candesartan 32 mg 1 time/day or conventional therapy immediately after AVR. Patients were followed with echocardiographic evaluations 3, 6, and 12 months after surgery. Primary end point was change in LV mass index. At baseline and during follow-up no differences in systolic, diastolic, and pulse pressures were seen between groups. Baseline LV mass index was 134 +/- 41 g/m(2) with no difference between groups. Mean decrease in LV mass index in the control group was 12 +/- 28 g/m(2) compared to 30 +/- 40 g/m(2) in the candesartan group (p = 0.015) during follow-up. After 12 months LV mass index was significantly lower in the candesartan group (103 +/- 29 vs 119 +/- 31 g/m(2), p = 0.01). In addition, the candesartan group had greater improvement in longitudinal LV systolic function assessed by tissue Doppler S' wave (0.6 +/- 0.1-cm/s increase in control group vs 1.4 +/- 0.1 cm/s in candesartan group, p = 0.01, p for trend = 0.02) and a decrease in LA volume (p for trend = 0.01). Treatment had no effect on diastolic E/e' ratio or B-type natriuretic peptide. In conclusion, angiotensin receptor blockade with candesartan after AVR in patients with AS is associated with augmented reverse LV and LA remodeling compared to conventional management.

Valve replacement for aortic stenosis normalizes subendocardial function in patients with normal ejection fraction

AIMS

Long-standing aortic stenosis (AS) causes various degrees of left ventricular (LV) dysfunction, which may improve after valve replacement. The aim of this study was to assess the nature of LV subendocardial abnormalities in AS and their response to valve replacement (AVR).

METHODS AND RESULTS

We studied 41 consecutive symptomatic patients (age 64 +/- 13 years) with severe AS, normal LV ejection fraction (EF), but no obstructive coronary artery disease before, a week after AVR, and 6 months after AVR. LV subendocardial function was studied from recordings of long-axis M-mode (amplitude), tissue-Doppler (myocardial velocities) and speckle tracking (myocardial strain) echocardiographic techniques. Results were compared with those from 20 age- and gender-matched controls. In patients, LV dimensions and markers of asynchrony, total isovolumic time (t-IVT), and Tei index were not different from controls before AVR and remained unchanged afterwards. LV lateral long-axis amplitude, as well as lateral and septal systolic velocities and strain, were reduced (P < 0.001 for all) and E/E' was modestly raised. Lateral long-axis amplitude, systolic and diastolic velocities normalized within a week of AVR but strain lagged behind until 6 months later. The reduced septal long-axis amplitude remained permanently unchanged (NS) despite the early normalization of its systolic velocities (P < 0.001) and strain (P < 0.001). LV mass normalized at 6 months after AVR (P < 0.005).

CONCLUSIONS

In patients with severe AS and maintained LV ejection fraction, subendocardial function is globally abnormal showing reduced amplitude of motion, velocities, and strain. The different response of its components suggests an evidence for differential reverse remodelling, irrespective of myocardial mass regression.

Plasma IL-18 and IL-18BP are altered differently in reverse remodeling following aortic valve replacement

OBJECTIVES

Patients with aortic stenosis (AS) develop left ventricular remodeling characterized by changes in extracellular matrix (ECM) and cardiomyocyte-hypertrophy. Aortic valve replacement (AVR) reverses this process (reverse remodeling). We examined plasma levels of interleukin-18 (IL-18) and its binding protein (IL-18BP) before and after AVR for AS since these mediators have been shown experimentally to exert effects on myocardial remodeling.

DESIGN

Plasma levels of IL-18 and IL-18BP were analyzed in 22 patients with AS undergoing AVR, preoperatively, two days, six and 12 months postoperatively. Echocardiography and functional testing were performed.

RESULTS

IL-18BP was significantly increased by 28% and 15% at two days and six months after AVR, compared to preoperative values. In contrast, IL-18 showed a later peak (increased by 24% at 12 months postoperatively) when IL-18BP was normalized. IL-18 correlated positively with deceleration time (R = 0.44) at this time-point which might indicate an association with diastolic function.

CONCLUSIONS

We report for the first time that plasma IL-18 and IL-18BP are differentially regulated after AVR for AS with an early increase in IL-18BP postoperatively followed by a later peak in IL-18 at 12 months. Given the known effects of these mediators on myocardial remodeling and function, they might play a role in the reverse and remodeling process associated with AVR.

Comparison of the hemodynamic performance of percutaneous and surgical bioprostheses for the treatment of severe aortic stenosis

OBJECTIVES

This study was undertaken to compare the hemodynamic performance of a percutaneous bioprosthesis to that of surgically implanted (stented and stentless) bioprostheses for the treatment of severe aortic stenosis.

METHODS

Fifty patients who underwent percutaneous aortic valve implantation (PAVI) with the Cribier-Edwards or Edwards SAPIEN bioprosthetic valve (Edwards Lifesciences, Inc., Irvine, California) were matched 1:1 for sex, aortic annulus diameter, left ventricular ejection fraction, body surface area, and body mass index, with 2 groups of 50 patients who underwent surgical aortic valve replacement (SAVR) with a stented valve (Edwards Perimount Magna [SAVR-ST group]), or a stentless valve (Medtronic Freestyle, Medtronic, Minneapolis, Minnesota [SAVR-SL group]). Doppler echocardiographic data were prospectively obtained before the intervention, at discharge, and at 6- to 12-month follow-up.

RESULTS

Mean transprosthetic gradient at discharge was lower (p < 0.001) in the PAVI group (10 +/- 4 mm Hg) compared with the SAVR-ST (13 +/- 5 mm Hg) and SAVR-SL (14 +/- 6 mm Hg) groups. Aortic regurgitation (AR) occurred more frequently in the PAVI group (mild: 42%, moderate: 8%) compared with the SAVR-ST (mild: 10%, moderate: 0%) and SAVR-SL (mild: 12%, moderate: 0%) groups (p < 0.0001). At follow-up, the mean gradient in the PAVI group remained lower (p < 0.001) than that of the SAVR-ST group, but was similar to that of the SAVR-SL group. The incidence of severe prosthesis-patient mismatch was significantly lower (p = 0.007) in the PAVI group (6%) compared with the SAVR-ST (28%) and SAVR-SL (20%) groups. However, the incidence of AR remained higher (p < 0.0001) in the PAVI group compared with the 2 other groups.

CONCLUSIONS

PAVI provided superior hemodynamic performance compared with the surgical bioprostheses in terms of transprosthetic gradient and prevention of severe prosthesis-patient mismatch, but was associated with a higher incidence of AR.

Feasibility of cardiovascular magnetic resonance to assess the orifice area of aortic bioprostheses

BACKGROUND

Prosthetic orifice area, usually calculated by transthoracic echocardiography (TTE) or transesophageal echocardiography (TEE), provides important information regarding the hemodynamic performance of aortic bioprostheses. However, both TTE and TEE have limitations; therefore accurate and reproducible determination of the orifice area often remains a challenge. The present study aimed to investigate the feasibility of cardiovascular magnetic resonance (CMR) to assess the orifice areas of aortic bioprostheses.

METHODS AND RESULTS

CMR planimetry of the orifice area was performed in 65 patients (43/22 stented/stentless prostheses; mean time since implantation, 3.1+/-2.8 years; mean orifice area [TTE], 1.70+/-0.43 cm(2); 62 normally functioning prostheses, 2 severe stenoses, and 1 severe regurgitation) in an imaging plane perpendicular to the transprosthetic flow using steady-state free-precession cine imaging under breath-hold conditions on a 1.5-T MR system. CMR results were compared with TTE (continuity equation, n=65) and TEE (planimetry, n=31). CMR planimetry was readily feasible in 80.0%; feasible with limitation in 15.4% because of stent, flow, and sternal wire artifacts; and impossible in 4.6% because of flow artifacts. Correlations of the orifice areas by CMR with TTE (r=0.82) and CMR with TEE (r=0.92) were significant. The average difference between the methods was -0.02+/-0.24 cm(2) (TTE) and 0.05+/-0.15 cm(2) (TEE). Agreement was present for stented and stentless devices and independent of orifice size. Intraobserver and interobserver variabilities of CMR planimetry were 6.7+/-5.4% and 11.5+/-7.8%.

CONCLUSIONS

The assessment of aortic bioprostheses with normal orifice areas by CMR is technically feasible and provides orifice areas with a close correlation to echocardiography and low observer dependency.