A novel comparison of stentless versus stented valves in the small aortic root

Surgical aortic valve replacement in small aortic annulus

BACKGROUND

Although aortic valve replacement (AVR) has been the standard of treatment for severe aortic stenosis, a small aortic annulus (SAA) poses significant challenges. Improvements in valve designs and evolution in surgical techniques have led to improved outcomes, however, the ideal prosthetic valve remains elusive.

METHODS

We performed a comprehensive literature review to discuss the surgical management of aortic stenosis, with a special focus on patients with SAA.

RESULTS

Stentless valves and root replacement techniques have been shown to overcome the hemodynamic challenges associated with conventional stented bioprostheses, but are technically challenging and require longer cross-clamp times. Sutureless and rapid deployment valves mitigate the long operative time while maintaining the hemodynamic advantages. The use of transcatheter AVR has emerged as another reasonable alternative and has shown promise among patients with SAA, however, long-term outcomes are awaited.

CONCLUSION

There is no consensus regarding the type of valve prosthesis or replacement technique among patients with SAA. Consideration of patient comorbidities and valvular anatomy is paramount in planning the optimal strategy for AVR. Further long-term clinical trials are necessary to assess outcomes and achieve progress toward the development of the ideal prosthesis.

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.

Early and Mid-term Outcome of the St. Jude Medical Regent 19-mm Aortic Valve Mechanical Prosthesis. Functional and Haemodynamic Evaluation

BACKGROUND AND OBJECTIVES

The aim of the present study is to report the early and mid-term clinical and haemodynamic results of the St Jude Medical Regent 19-mm aortic mechanical prothesis (SJMR-19).

MATERIALS AND METHODS

Between January 2002 and January 2012, 265 patients with aortic valve disease underwent AVR (Aortic Valve Replacement) with a SJMR-19 (St Jude Medical Regent Nr.19). There were 51 males. Mean age was 67.5±12.72years and mean body surface area (BSA) was 1.67±0.14m2. Thirty-six patients required annulus enlargement. The mean follow-up was 34.5±18.8months (range 6-60 months). All patients underwent echocardiographic examination at discharge and within 1 year after surgery.

RESULTS

There were 14 (5.3%) hospital deaths. Six of the hospital deaths were identified in patients undergoing reoperation, significantly higher than patients undergoing first time operation (p=0.0001). Also the postoperative mortality was significantly higher in patients undergoing annulus enlargement versus patients not requiring annulus enlargement (p=0.02). The mean transprosthesis gradient at discharge was 19±9mmHg. At 6 months follow-up the mean NYHA FC class was 1.6±0.5 significantly lower than preoperatively 2.4±0.75 (p <0.0001). The M-TPG was 15.2±6.5mmHg within 1 year after surgery. Left ventricular mass (LVM) and indexed left ventricular mass (LVM_i) were significantly lower than preoperatively The actuarial survival and cumulative freedom from reoperation at 1, 2 and 3 years follow-up were 99.5%, 97.5%, 96.7% and 99.2%, 96.5%, 94.5% respectively. The cumulative actuarial free-events survival at 4 years was 92%. The Cox model identified age (p=0.015), LVEF≤35% (p=0.043), reoperation (p=0.031), combined surgery (p=0.00002), and annulus enlargement (p=0.015) as strong predictors for poor actuarial free-major events survival.

CONCLUSIONS

The SJMR-19 offers excellent postoperative clinical, haemodynamic outcome and LVM_i reduction in patients with small aortic annulus. These data demonstrate that the modern St Jude small mechanical protheses do not influence the intermediate free-reoperation survival.

Long-term Mortality Predictors in Patients with Small Aortic Annulus Undergoing Aortic Valve Replacement with a 19- or 21-mm Bioprosthesis

Introduction

Replacement of the aortic valve in patients with a small aortic annulus is associated with increased morbidity and mortality. A prosthesis-patient mismatch is one of the main problems associated with failed valves in this patient population.

Objective

To evaluate the long-term mortality predictors in patients with a small aortic annulus undergoing aortic valve replacement with a bioprosthesis.

Methods

In this retrospective observational study, a total of 101 patients undergoing aortic valve replacement from January 2000 to December 2010 were studied. There were 81 (80.19%) women with a mean age of 52.81±18.4 years. Severe aortic stenosis was the main indication for surgery in 54 (53.4%) patients. Posterior annulus enlargement was performed in 16 (15.8%) patients. Overall, 54 (53.41%) patients underwent concomitant surgery: 28 (27.5%) underwent mitral valve replacement, and 13 (12.7%) underwent coronary artery bypass graft surgery.

Results

Mean valve index was 0.82±0.08 cm(2)/m(2). Overall, 17 (16.83%) patients had a valve index lower than 0.75 cm(2)/m(2), without statistical significance for mortality (P=0.12). The overall 10-year survival rate was 83.17%. The rate for patients who underwent isolated aortic valve replacement was 91.3% and 73.1% (P=0.02) for patients who underwent concomitant surgery. In the univariate analysis, the main predictors of mortality were preoperative ejection fraction (P=0.02; HR 0.01) and EuroSCORE II results (P=0.00000042; HR 1.13). In the multivariate analysis, the main predictors of mortality were age (P=0.01, HR 1.04) and concomitant surgery (P=0.01, HR 5.04). Those relationships were statistically significant.

Conclusion

A valve index of < 0.75 cm(2)/m(2) did not affect 10-year survival. However, concomitant surgery and age significantly affected mortality.

Early and mid-term outcome in terms of functional and hemodynamic performance of the st. Jude regent 19-mm aortic mechanical prosthesis versus 19-mm carpentier edwards aortic biological prosthesis

BACKGROUND

The aim of the present study is to compare the early and mid-term clinical and hemodynamic results of the aortic valve replacement (AVR) with a St Jude Medical Regent 19-mm prosthesis (SJMR-19) versus Carpentied-Edwars bovine pericardial 19-mm valve (CE-19).

METHODS

Between January 2002 and January 2012, 265 patients (Group I) and 58 patients (Group II) with underwent AVR with a SJMR-19 and CE-19 respectively. There were no significant differences between groups regarding the demographic and preoperative echocardiographic data. Thirty-six patients in Group I and 4 in Group II required annulus enlargement in association or not with septal myectomy. The mean follow-up was 34 ± 18.5 months (range 5-60 months).

RESULTS

There were 14 (5.3 %) hospital deaths in Group I versus 4 (6.8 %) in Group II (p = 0.86). The multivariate logistic regression analysis identified the LVEF ≤ 35 % (p = 0.001), combined operation (p = 0.0005), CPB (p = 0.033), age (p = 0.011), annulus enlargement (p = 0.0009), reoperation (p = 0.039) and chronic renal failure (p = 0.011) as strong predictors for early postoperative death. Within 1 year after surgery peak pulmonary artery pressure, interventricular septal and left ventricular posterior wall thickness decreased significantly in both groups. The M-TPG was 15.7 ± 6.5 mmHg in Group I versus 17 ± 7 mmHg in Group II (p = 0.19). The multivariate regression analysis revealed the annulus enlargement (p = 0.018), small EOAi (p = 0.00004), postoperative LVMi (p = 0.0001) and BSA (p = 0.019) as strong predictors for higher M-TPG. The postoperative LVMi was 119 ± 22.5 gm/m(2) in Group I and 122 ± 22 gm/m(2) in Group II (p = 0.37), significantly lower than the respective preoperative values 162.5 ± 34 gm/m(2) (Group I) and 168 ± 30 gm/m(2) (Group II). The actuarial survival and cumulative free-reoperation actuarial survival at 5 years follow-up were 96.7 and 94.5 % respectively in Group I and 97 and 91 % in Group II.. There were non significant differences between groups regarding the actuarial survival and cumulative free-reoperation survival. The Cox model identified the older age (p = 0.022), LVEF ≤ 35 % (p = 0.009), reoperation (p = 0.018), combined surgery (p = 0.00075) and annulus enlargement (p = 0.033) as strong predictors for poor actuarial free-reoperation survival.

CONCLUSIONS

Both the SJMR-19 and CE-19 offers excellent postoperative clinical and hemodynamic outcome in patients with small aortic annulus. The LV hypertrophy and transvalvular gradients are reduced significantly indenpendently of the employed SJMR-19 or CE-19 prosthesis. Our data support recent suggestions that small valve size does not influence intermediate free-reoperation survival. The CE-19 is an excellent alternative to SJMR-19 in old patients.

Normal aortic valves stay open much longer in systole than porcine substitutes

OBJECTIVE

To compare the opening mechanics of porcine valve substitutes with those of a normal human aortic valve.

BACKGROUND

All commercially available porcine valves are pretreated with glutaraldehyde. This study was undertaken to evaluate the consequences of such treatment on valve mechanics.

METHODS

The opening mechanics of the aortic valve, especially the time taken to open fully from a closed position, and the duration for which the valve is maximally open, were compared in a normal aortic valve, a stent-mounted porcine valve, and a stentless porcine valve, using a finite element model.

RESULTS

Despite a 4-fold higher gradient, stent-mounted porcine valves were slower in attaining the fully open position, and the time for which the valve was fully open was almost 25% less than a normal valve. In stentless valves, the compliant root made the initial opening mechanics similar to those of a normal valve. Once this effect was over, the effect of porcine leaflet properties took over, and there was a corresponding delay in the valve opening.

CONCLUSIONS

Fixing the root with a stent and stiffening the leaflets with glutaraldehyde result in delayed valve opening and decrease the duration for which the valve is fully open, thus contributing to inferior hemodynamics.

Long-term follow-up of stentless prosthesis

BACKGROUND

Stentless prostheses have an interesting hemodynamic performance when compared to stented prostheses and are recommended in cases of small aortic annulus.

MATERIALS AND METHODS

From January 1996 to January 2004, 138 patients suffering from aortic disease, underwent aortic valve replacement. • Group A: 93 patients underwent stentless aortic valve implantation [stentless Biocor (Biocor Industria e Pesguisa Ltda, Belo Horizonte, Brazil) and stentless Sorin (Sorin Group, Saluggia, Italy)]. • Group B: 45 patients underwent stented aortic valve implantation (stented Biocor). Patients were assessed by clinical evaluation and echocardiography after a mean follow up of 124.5 ± 58.2 months.

RESULTS

There was a significant difference in terms of time of extracorporeal circulation and aortic cross clamp. The actuarial survival at 4, 8, 12, and 15 years is 77%, 50%, 21%, and 18%, respectively. Freedom from reoperation at 4, 8, 12, and 14 years was 92%, 83%, 73%, and 63%, respectively. Freedom from all events, death, and reoperation at 4, 8, 12, and 14 years was 70%, 39%, 13%, and 8%, respectively. There is no statistical difference among the two groups in terms of actuarial survival, freedom from reoperation, and freedom from re-hospitalization for prosthesis-related causes.

DISCUSSION

There was a significantly higher incidence of pacemaker implantation in Group A and the causes are not known. The rate of freedom from reoperation is high in both groups for the patients who remained alive. There was no statistical difference about prosthesis dysfunction between the two groups. The higher incidence of death in Group A cannot be explained by causes related to the prosthesis because there is no difference in terms of causes of death. Rates of reoperation did not differ between the two groups.

CONCLUSIONS

The results obtained with stentless prostheses are encouraging even in long-term follow-up.

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.

Impact of Stentless Aortic Valves on Left Ventricular Function and Hypertrophy: Current Best Available Evidence

Past four decades have seen a gradual evolution in aortic valve replacement surgery. The ideal valve substitute should combine central flow, low transvalvular gradient, low thrombogenicity, durability, easy availability, resistance to infection, freedom from anticoagulation, and easy implantability. Although there are several types of valves available to replace the diseased aortic valve-autograft, allograft, xenograft, mechanical, and bioprosthetic valves-none is ideal. On one end of the spectrum is the pulmonary autograft, which comes closest to achieving these goals, but creates a double valve procedure for single valve disease, while on the other end are the mechanical valves and stented tissue valves, which allow easy "off the shelf" availability as well as easy implantability but are limited by the potential drawback of causing intrinsic obstruction to some extent because of the space occupied by the stent and sewing ring. Stentless xenograft aortic valves have been developed as a compromise between these ends of the valve spectrum. Stentless aortic valves have been reported to provide more physiologic hemodynamic behavior and cause more timely and thorough regression of ventricular hypertrophy. This review article attempts to evaluate current best available evidence from randomized controlled trials to assess the impact of stentless aortic valves on left ventricular function and hypertrophy.

Carpentier-Edwards PERIMOUNT Magna bioprosthesis: A stented valve with stentless performance?

OBJECTIVE

We designed this study to evaluate the early hemodynamic performance of the recently introduced Carpentier-Edwards PERIMOUNT Magna bioprosthesis (Edwards Lifesciences, Irvine, Calif) and compare it with those of the conventional Carpentier-Edwards PERIMOUNT stented bioprosthesis (Edwards Lifesciences) and Edwards Prima Plus porcine stentless bioprosthesis (Edwards Lifesciences).

METHODS

Sixty-three patients (>70 years old) were enrolled in this prospective, randomized study. At operation, once the annulus had been measured, the best size suitable was assessed for each of the three valves before random assignment. Transthoracic echocardiography was performed before discharge to evaluate early postoperative hemodynamic performances of the different valves implanted.

RESULTS

The best size suitable of Edwards Prima Plus (24.3 +/- 1.7 mm) was significantly superior to those of both the Carpentier-Edwards PERIMOUNT Magna (23.4 +/- 2.1 mm) and Carpentier-Edwards PERIMOUNT (22.4 +/- 1.8 mm). The best size suitable of the Carpentier-Edwards PERIMOUNT Magna, however, was significantly superior to that of the Carpentier-Edwards PERIMOUNT. Furthermore the best size suitable of the Carpentier-Edwards PERIMOUNT Magna was equal to the measured annulus in 55% of patients, as opposed to 25% for the Carpentier-Edwards PERIMOUNT (P < .001). Mean implanted labeled size of the Edwards Prima Plus was significantly higher than those of both the Carpentier-Edwards PERIMOUNT Magna and the Carpentier-Edwards PERIMOUNT (24.6 +/- 1.9 mm, 23.1 +/- 1.9 mm, and 22.5 +/- 1.8 mm, respectively). Early postoperative hemodynamic performance of the Carpentier-Edwards PERIMOUNT Magna, however, was superior to those of both the Edwards Prima Plus and the Carpentier-Edwards PERIMOUNT in both effective orifice area index (1.07 +/- 0.4 cm2/m2, 0.87 +/- 0.3 cm2/m2, and 0.80 +/- 0.2 cm2/m2, respectively) and mean peak gradient (20 +/- 6 mm Hg, 27 +/- 8 mm Hg, and 28 +/- 12 mm Hg, respectively).

CONCLUSION

The improved design of the recently introduced third-generation stented bioprosthesis Carpentier-Edwards PERIMOUNT Magna allows implantation of a significantly bigger valve than with the old generation. Furthermore, the improved hemodynamic performance of the Carpentier-Edwards PERIMOUNT Magna compares favorably with both the Carpentier-Edwards PERIMOUNT and the Edwards Prima Plus.

Patient‐Prosthesis Mismatch After Small‐Size Stentless Aortic Valve Replacement

OBJECTIVE

The aim of this study was to determine the occurrence of patient-prosthesis mismatch (P-PM) after aortic valve replacement (AVR) with a small-size Cryolife O'Brien (CLOB) bioprosthesis and to evaluate its clinical and hemodynamic implications.

METHODS

Sixty-two patients (mean age 70.9 +/- 5.2 years, 77.8% females), receiving a labeled 21-23 mm CLOB between 1993 and 2000, were retrospectively studied. Effective orifice area (EOA) was calculated by the continuity equation and then indexed to the patient's body surface area (BSA) to obtain the indexed EOA (EOAI). Based on previous observations a mismatch was defined as EOAI <or= 0.85 cm2/m2.

RESULTS

Twelve patients (20%) at discharge, two (3.3%) at 6 months and none at late controls had an EOAI <or= 0.85 cm2/m2. At ANOVA determinants of mismatch were female sex (p < 0.001), age (p = 0.01), and patient's annulus index (PAI, p < 0.001). Patients with mismatch had higher mean gradients (MG, p = 0.01, and p < 0.001 at discharge and 6 months, respectively) and EOAI correlated with MG at discharge (r2= 0.72, p < 0.001) and 6-month (r2= 0.40, p = 0.001) studies. At 1 year no difference in MG was detected between patients with or without mismatch (p = ns) and EOAI did not correlate with MG (r2= 0.01, p = ns). Midwall fractional shortening did not differ in patients with or without mismatch (p = ns). Patients with an EOAI >or= 0.8 cm/m2 showed an earlier concentric remodeling up to 1 year; no difference was demonstrated at later studies between groups. Survival and clinical status results were not affected by an EOAI <or= 0.85 cm2/m2.

CONCLUSIONS

After AVR with CLOB mismatch occurred early postoperatively in a small number of patients without clinical repercussions. EOAI, significantly increasing over time, was adequate to BSA in all patients at late controls.

Prosthesis size and long-term survival after aortic valve replacement

OBJECTIVE

This study was undertaken to quantify the relationship between prosthesis size adjusted for patient size (prosthesis-patient size) and long-term survival after aortic valve replacement.

METHODS

Data from nine representative sources on 13,258 aortic valve replacements provided 69,780 patient-years of follow-up (mean 5.3 +/- 4.7 years), with reliable survival estimates to 15 years. Prostheses included 5757 stented porcine xenografts, 3198 stented bovine pericardial xenografts, 3583 mechanical valves, and 720 allografts. Manufacturers' labeled prosthesis size was 19 mm or smaller in 1109 patients. Expressions of prosthesis-patient size assessed were indexed internal prosthesis orifice area (in centimeters squared per square meter of body surface area) and standardized internal prosthesis orifice size (Z, the number of SDs from mean normal native aortic valve size). Multivariable hazard domain analysis with balancing score and risk factor adjustment quantified the association of prosthesis-patient size with survival.

RESULTS

Prosthesis-patient size down to at least 1.1 cm(2)/m(2) or -3 Z did not adversely affect intermediate- or long-term survival (P >.2). However, 30-day mortality increased 1% to 2% when indexed orifice area fell below 1.2 cm(2)/m(2) (P =.002) or standardized orifice size fell below -2.5 Z (P =.0003). The increased early risk affected fewer than 1% of patients receiving bioprostheses but about 25% of those receiving mechanical devices.

CONCLUSIONS

Aortic prosthesis-patient size down to 1.1 cm(2)/m(2) or -3 Z did not reduce intermediate- or long-term survival after aortic valve replacement. However, patient-prosthesis size under 1.2 cm(2)/m(2) or -2.5 Z was associated with a 1% to 2% increase in 30-day mortality. Prosthesis-patient sizes this small or smaller were rarely implanted in patients receiving bioprostheses.

Quantification of haemodynamic performance of stented and stentless aortic bioprostheses and potential influence on survival

BACKGROUND

The goal of aortic valve replacement is relief of symptoms, optimisation of haemodynamics, regression of left ventricular mass and advancement of survival. The objective of this review article is to provide the evidence-to-date on the clinical performance of stented and stentless heterograft bioprostheses with regard to haemodynamics, durability and survival.

METHODS

The haemodynamic advantage of aortic valve replacement prostheses is judged on ability to minimise postoperative gradients and to optimise the normalisation of left ventricular mass and function. The most frequent cause of high postoperative gradients occurs when the effective prosthetic valve area is less than that of the normal human valve. The effective orifice area index (EOAI) of >/= 0.85 cm(2)/m(2) is considered optimal to prevent patient-prosthesis mismatch (PPM) at rest and exercise.

RESULTS

The stented bioprostheses contribute to obstructive non-physiological flow patterns whereas stentless bioprostheses provide laminar non-obstructive flow. The stentless bioprostheses have been shown to have larger effective orifice areas and lower gradients. Mismatch is decreased with stentless bioprostheses especially when prosthesis size is </=21 mm. Left ventricular mass (LVM) postoperatively has been shown to relate to baseline LVM index (LVMI) and PPM. The EOAI >0.8 cm(2)/m(2) provides the best long-term regression of LVM. It has been identified that a tendency for PPM in sizes 21 and 23 mm stented bioprostheses did not prevent adequate achievement of appropriate LVMI. Survival at 5 years favoured stentless over stented bioprostheses for patients <70 years, but not in patients >/= _70 years of age. The durability comparison of the stentless bioprostheses must wait until 10-15 years experience is achieved. There is preliminary evidence that uneven shear stress on the leaflet of a regurgitant stentless bioprosthesis can accelerate leaflet tears at the level of the commissures. Dilation of the aortic root and, particularly, the sinotubular junction, can cause progressive stentless valve insufficiency.

CONCLUSIONS

The long-term performance advantages or disadvantages of stentless bioprostheses compared to stented bioprostheses will require at least another 5-7 years of cumulative stentless bioprostheses experience. Surgeons can use an algorithm intraoperatively to prevent patient-prosthesis mismatch while choosing the optimal prosthesis.

Survival after stentless and stented xenograft aortic valve replacement: a concurrent, controlled trial

BACKGROUND

To define the impact of stentless versus stented valve design on survival late after xenograft aortic valve replacement, a retrospective analysis of all consecutive patients operated on between January 1992 and April 2000 was undertaken.

METHODS

Two hundred ninety-two patients had stented (group 1) and 376 stentless (group 2) xenograft aortic valve replacements. Age was older in group 1 (75 +/- 4 vs 70 +/- 7 years, p = 0.01), whereas male gender and aortic stenosis were equally prevalent. Advanced New York Heart Association class III-IV (85% vs 78%, p = 0.03) and associated procedures (53% vs 41%, p = 0.01) were more common in group 1. Aortic cross-clamp (80 +/- 28 vs 96 +/- 23 minutes, p = 0.01) and bypass (91 +/- 56 vs 129 +/- 34 minutes, p = 0.01) times were shorter in group 1. Logistic regression and Cox proportional hazard methods were used to define the role of demographic and operative variables on hospital and late survival, freedom from valve-related mortality, and reintervention.

RESULTS

Early mortality was higher in group 1 (6.2% vs 2.6%, p = 0.02). Smaller aortic anulus (p = 0.008), aortic cross-clamp (p = 0.03), and coronary disease requiring bypass (p = 0.03) were associated with hospital mortality. During follow-up (37 +/- 30 vs 43 +/- 35 months, p = NS), 66 late deaths were recorded (12% vs 9%, p = NS). At 8 years, survival (70 +/- 5% vs 81 +/- 3%, p = 0.01), freedom from cardiac- (85 +/- 1% vs 92 +/- 3%, p = 0.02), and valve-related death (79 +/- 5% vs 95 +/- 2%, p = 0.004) were higher in group 2. Freedom from structural deterioration was similar (92 +/- 5% vs 93 +/- 3%, p = NS), but freedom from reoperation was lower in group 2 (99 +/- 1% vs 90 +/- 4%, p = 0.009). Multivariate analysis showed female gender (p = 0.02), age (p = 0.03), and smaller valve size (p = 0.05) to be associated with late mortality; age (p = 0.06) and diagnosis of aortic stenosis (p = 0.008) with cardiac mortality; longer intensive care unit stay (p = 0.001) and stented xenografts (p = 0.05) with valve-related mortality; and younger age (p = 0.01) and stentless xenograft (p = 0.05) with reoperation.

CONCLUSIONS

Use of stentless xenografts correlates with better survival and freedom from cardiac- and valve-related mortality than stented valves. However, bias favoring stented valves in older and sicker patients exists. Selective survival advantage of stentless xenograft is confined to valve-related mortality. Stentless valves are more likely to be replaced for dysfunction.

Usefulness of the Cryolife O'Brien stentless suprannular aortic valve to prevent prosthesis-patient mismatch in the small aortic root

OBJECTIVES

This study evaluated the occurrence of prosthesis-patient mismatch (PPM) after Cryolife O'Brien (CLOB) suprannular stentless valve replacement in patients with a small aortic root and its repercussions on the patient's hemodynamic status and left ventricular mass regression.

BACKGROUND

The correct management of the small aortic annulus is still controversial. Small aortic prostheses can lead to a PPM, which results in high gradients with important repercussions on the hemodynamic status.

METHODS

Seventy-two patients (mean age: 72.5 +/- 6.2 years, 73.6% women) with a small aortic root (< or =21 mm intraoperatively measured aortic annulus) had a CLOB valve implanted in the aortic position between November 1993 and July 2001 at our institution. Mean prosthesis size was 22.0 +/- 0.8 mm. Patients underwent echocardiography preoperatively, at discharge, six months, one year and yearly thereafter.

RESULTS

The incidence of PPM at discharge was 22.2% (16/72); 18.7% were severe (effective orifice area index [EOAI] < or =0.65 cm/m(2)), 43.7% were moderate (EOAI = 0.66 to 0.75 cm/m(2)) and 37.6% were mild (0.76 to 0.85 cm/m(2)). At multivariable analysis, gender (p < 0.001), age (p = 0.015), body surface area (p < 0.001) and patient's annulus index (p < 0.001) were significant factors influencing the occurrence of "transient" PPM. At one year the incidence of PPM was 0%. CONCLUSIONS; Suprannular CLOB valve yielded excellent hemodynamic results in patients with small aortic roots. This study demonstrates that PPM can be completely avoided when using the CLOB valve. The superior hemodynamics of this stentless valve are likely to be related to its suprannular design.

Hemodynamic stability during 17 years of the Carpentier-Edwards aortic pericardial bioprosthesis

BACKGROUND

Long-term stability of the hemodynamic performance of commercially available Carpentier-Edwards stented bovine pericardial aortic bioprostheses (Perimount RSR) is unknown. To anticipate the fate of this bioprosthesis, we examined its hemodynamic performance up to 17 years using echocardiographic studies in a Premarket Approval cohort.

METHODS

Of 267 patients at four institutions in the Premarket Approval cohort, 85 had a total of 168 echocardiographic studies during a 17-year period of yearly follow-up examinations. These were reviewed and quantified in a core echocardiographic facility. Longitudinal data analysis was used to account for repeated, censored data.

RESULTS

Mean transvalvular gradient was inversely related to prosthesis size (p = 0.01), and possibly (p = 0.06) increased somewhat during the first 10 years of follow-up, then stabilized. Effective orifice area was larger in larger valve sizes (p = 0.01), declined somewhat during the first 10 years, and then began to increase again. Ejection fraction declined minimally (p = 0.2). In contrast to the rather stable hemodynamics, aortic regurgitation steadily increased from none to 1 to 2+ (p = 0.005), but rarely (< 10% at 17 years) progressed to 3+ or 4+.

CONCLUSIONS

The Carpentier-Edwards aortic pericardial bioprosthesis can be anticipated to have an acceptable long-term transvalvular gradient and effective orifice size that will change trivially up to 17 years after implantation. Mild aortic regurgitation will develop progressively. This anticipated hemodynamic resilience supports continued clinical use of the Perimount Carpentier-Edwards bovine pericardial stented bioprosthesis.

Time course of left ventricular remodeling after stentless aortic valve replacement

BACKGROUND

Stentless aortic valves are associated with a significant decrease in left ventricular hypertrophy. This study examined the time course and factors affecting left ventricular mass regression (LVMR) after aortic valve replacement (AVR) with Cryolife O'Brien (CLOB) (Cryolife International, Atlanta, Ga) stentless valves.

METHODS

Between 1993 and 2000, 130 consecutive patients underwent AVR with CLOB. Mean age was 71.3 +/- 6.3 years. Sixty-four (49.2%) were male. Mean body surface area (BSA) was 1.7 +/- 0.2 m(2). Mean valve size implanted was 23.6 +/- 2.0 mm. All patients were monitored with serial echocardiograms; the first study was performed preoperatively, and subsequent controls were at 6 months, 1, 2, 3, 4, 5, 6, and 7 years, respectively. Left ventricular mass was calculated by the Devereux formula and indexed by BSA.

RESULTS

Analysis of variance showed a significant reduction in the left ventricular mass index (LVMI) over time (P < .001). Most LVMRs occurred within the first 6 months, and after 1 year LVMI had decreased by 37.5% with further, but not statistically significant, reductions at later examinations. We found that baseline BSA > 1.75 m(2), male sex, arterial blood pressure > or = 150 mm Hg, left ventricular ejection fraction < or = 35%, New York Heart Association functional class > or = III, non-sinus rhythm, and prevalent aortic incompetence to be factors influencing LVMR. LVMR was not related to postoperative effective orifice area < or = 0.85 cm/m(2) and prosthetic size.

CONCLUSIONS

AVR with a CLOB valve is followed by a significant LVMR that occurs soon after surgery. It is influenced by several patient-related factors: most of them can be predicted preoperatively.

Hemodynamic performance of stented and stentless aortic bioprostheses

BACKGROUND

This study compares the hemodynamic performance of stented and stentless bioprostheses used for aortic valve replacement in patients with aortic stenosis and small aortic root.

METHODS

Between 1995 and 1998, 37 patients with a 21-mm aortic annulus (group 1) underwent aortic valve replacement with either a 21-mm Edwards Perimount or a 23-mm St. Jude Toronto bioprosthesis whereas 47 patients with a 23-mm aortic annulus (group 2) received either a 23-mm Medtronic Mosaic or a 25-mm Edwards Prima bioprosthesis. In each group mean and peak gradients, effective orifice area index, and left ventricular mass index were compared during follow-up.

RESULTS

Group 1 patients showed a significant reduction of mean (p < 0.001) and peak gradients (p = 0.001) during follow-up, more evident for St. Jude Toronto versus Edwards Perimount (p = 0.02 and p = 0.05, respectively). Group 2 patients showed a significant reduction of mean and peak gradients (p < 0.001), more evident for Edwards Prima versus Medtronic Mosaic (p < 0.001 and p = 0.07, respectively). Effective orifice area index significantly increased only in group 1 (p = 0.005). Left ventricular mass index significantly decreased in all patients regardless of the type of valve (p < 0.001). Patients with Edwards Prima showed a trend to a higher regression of left ventricular mass index versus Medtronic Mosaic recipients (p = 0.07).

CONCLUSIONS

After aortic valve replacement, stented and stentless bioprostheses exhibited similar results with a more evident hemodynamic improvement during follow-up in the stentless valves. Stented bioprostheses of new generation, however, may parallel the hemodynamic performance of stentless valves and appear to be a valid alternative for aortic valve replacement in elderly patients with a small aortic annulus.

Hemodynamic comparison of second- and third-generation stented bioprostheses in aortic valve replacement

BACKGROUND

The hemodynamic performance of aortic replacement prostheses is of extreme importance. There is renewed interest in hemodynamics because of the influence of prosthesis-patient mismatch on left ventricular mass regression and the potential influence on survival.

METHODS

The hemodynamic performance of the second-generation Carpentier-Edwards supraannular porcine and pericardial (Perimount) bioprostheses and the third-generation Medtronic Mosaic porcine bioprosthesis were compared for mean gradient and effective orifice area index. The effective orifice area index of at least 0.85 cm2/M2 was considered as lack of prosthesis-patient mismatch. The study group included included 53 patients with Carpentier-Edwards supraannular porcine, 48 with pericardial, and 98 with Medtronic Mosaic porcine bioprostheses.

RESULTS

The mean gradients were not different between the prostheses by prosthesis size. The Medtronic Mosaic was not provided in size 19. The mean gradients for the prostheses, except in the very large sizes, were all double-digit values. The effective orifice area index was not different between the prostheses but there was a trend toward prosthesis-patient mismatch in smaller size prostheses.

CONCLUSIONS

There was no apparent hemodynamic advantage between porcine and pericardial bioprostheses in the aortic position.

Prosthesis-Patient Mismatch Affects Survival After Aortic Valve Replacement

Background —Surgeons traditionally avoid the use of “small” aortic prostheses because of the potential for residual left ventricular outflow tract obstruction and persistent transvalvular gradients. This study examines the ratio between prosthetic valve size and the body surface area (BSA) of patients undergoing aortic valve replacement (AVR). We sought to determine the effect of potential “prosthesis-patient” mismatch on long-term survival.

Methods and Results —Follow-up was conducted on 2981 patients who underwent AVR with stented bioprostheses between 1976 and 1996. To account for differences between manufacturers’ labeled valve sizes, we calculated the ratio between the prosthetic valve effective orifice area (EOA) and the patient’s BSA (recorded for 2154 patients). The lowest decile in this cohort had a calculated EOA/BSA of <0.75 cm 2 /m 2 (Small group, n=227) compared with the control group (n=1927), in whom the EOA/BSA ratio was >0.75 cm 2 /m 2 . Operative mortality was higher in the Small group (8% versus 5%, P =0.03). Actuarial survival at 12 years was 50±5% in the Small group compared with 49±2% in the control group ( P =0.27). However, freedom from valve-related mortality was significantly lower in the Small group (75±5% versus 84±2%, P =0.004). Cox regression analysis determined age and NYHA functional class to be the multivariate predictors of overall mortality, whereas advanced age and EOA/BSA <0.75 cm 2 /m 2 were found to be the predictors of valve-related mortality.

Conclusions —Prosthesis-patient mismatch results in significantly higher early and late mortality after bioprosthetic AVR. We recommend careful selection of stented bioprostheses to ensure an adequate ratio of EOA to BSA. An EOA/BSA ratio of >0.75 cm 2 /m 2 may avoid residual left ventricular outflow tract obstruction and persistent transvalvular gradients. Careful prosthesis-patient matching will improve both early and late survival after AVR.

Impact of small prosthetic valve size on operative mortality in elderly patients after aortic valve replacement for aortic stenosis: does gender matter?

OBJECTIVE

Ideal management of the elderly patient with a small aortic root remains controversial. This retrospective analysis was performed to determine whether small prosthetic valve size is related to outcome in patients 70 years of age or older undergoing aortic valve replacement for aortic stenosis.

METHODS

Between December 1991 and July 1998, 366 patients 70 years of age or older (median age 77 years, range 73-81 years, 49% male) underwent isolated aortic valve replacement or aortic valve replacement with coronary bypass grafting with standard Carpentier-Edwards bovine pericardial valves (Baxter Healthcare Corp, Edwards Division, Santa Ana, Calif) (n = 277; 76%) or St Jude Medical mechanical valves (St Jude Medical, Inc, St Paul, Minn) (n = 89; 24%). Propensity scoring and multivariable regression models were used to evaluate the risks associated with implantation of 19-mm valves.

RESULTS

Operative mortality was 16.7% (17/102) in patients who received 19-mm valves and 3% (8/264) among those receiving >/=21-mm valves (P </=.0005). The univariable odds ratio for operative death for 19-mm versus >/=21-mm valves was 6.4 (95% CI 2.7, 15.4; P </=.0005). In the final multivariable model, receipt of a 19-mm valve alone was not a statistically significant predictor of operative death (odds ratio 2. 1; 95% CI 0.7, 6.4; P =.21). However, the combination of male sex and 19-mm valve resulted in a significant risk of operative death (4/9 patients; odds ratio 17.5; 95% CI 2.2, 139; P =.007). Use of a 19-mm valve was not related to late death in either the univariable (hazard ratio 1.0; 95% CI 0.5, 2.0; P =.95) or the multivariable analysis (hazard ratio 0.7; 95% CI 0.3, 1.8; P =.51).

CONCLUSIONS

Implantation of a standard 19-mm aortic valve in elderly men with aortic stenosis may be associated with an increased risk of operative mortality. A higher performance valve and/or a root enlargement procedure should be considered in men with a measured 19-mm anulus.