Ten-Year Experience With Stentless Aortic Valves: Full-Root Versus Subcoronary Implantation

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

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

Current indications for stentless aortic bioprostheses

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

Freestyle stentless bioprosthesis for aortic valve therapy: 17-year clinical results

BACKGROUND

Aortic valve replacement with stentless bioprostheses has been shown to produce lower aortic gradients than stented bioprostheses, thus facilitating left ventricular mass regression and preventing heart failure. We sought to determine the long-term results of stentless biological aortic valve replacement over a 17-year follow-up.

METHODS

Between 1996 and 2012, 2551 patients underwent isolated aortic valve replacement with a stentless prosthesis (Medtronic Freestyle) at a single center. The mean patient age was 72 ± 10 years, 55% were male, 24.1% were in New York Heart Association class I and II, 9.6% had undergone previous surgery, 18.1% had coronary artery disease, and 23.1% had diabetes. For the long-term follow-up, patients were contacted in writing and by telephone; follow-up was 96.3% complete, resulting in 11,546 patient-years.

RESULTS

At 30 days, mortality (5.4%), renal failure (3.9%), myocardial infarction (0.7%), and stroke (1.4%) rates were acceptable. During long-term follow-up of 1-17 years, the bleeding rate (2.9%) was higher than the thromboembolic event rate (0.7%) despite 18.1% of patients being on oral anticoagulants. New pacemaker implantation (4.5%; 0.87 events/100 patient-years), neurological disorders (5%; 0.52 events/100 patient-years), valve insufficiency (0.7%; 0.16 events/100 patient-years), paravalvular leakage (0.4%; 0.09 events/100 patient-years) and reoperation due to valvular complications (0.7%; 0.38 events/100 patient-years) were rare. Long-term survival was 41.8% ± 1.6 after 10 years, 21.3% ± 2.3 after 15 years, and 12.1% ± 3.9 after 17 years.

CONCLUSION

Long-term results after aortic valve replacement with stentless biological prostheses compare favorably with those obtained with stented bioprostheses.

Pseudoaneurysm formation after medtronic freestyle porcine aortic bioprosthesis implantation: a word of caution

BACKGROUND

A growing literature describes aneurysmal deterioration after implantation of the stentless porcine aortic Medtronic Freestyle bioprosthesis (MFB; Medtronic Inc, Minneapolis, MN), with some suggesting inadequate tissue fixation with immune response as a cause. However, disjointed reports make the significance of these findings difficult to interpret. We address this concern by aggregating available data.

METHODS

We reviewed institutional data, the Food and Drug Administration's Manufacturer and User Facility Device Experience registry, and the medical literature for mention of aneurysm or pseudoaneurysm after MFB. Case details were aggregated, and the rate of aneurysmal deterioration was estimated. Immunohistopathologic examination of institutional explanted specimens was performed to elucidate a cause.

RESULTS

We found 42 cases of aneurysmal deterioration with adequate detail for analysis; all occurred with full root replacement and valve sizes ranging from 23 to 29 mm. The rate of aneurysmal deterioration considering all data sources was 1.1% (9 of 851; 95% confidence interval, 0.5% to 2.0%) vs 4.7% (4 of 86; 95% confidence interval, 1.3% to 11.5%) at our institution, where yearly surveillance imaging is performed. Rate of aneurysmal deterioration appeared constant until 5 years after the operation; however, events are reported out to 10 years. Consistent with previous reports, histopathology demonstrated an immune cell infiltrate in areas of MFB wall breakdown.

CONCLUSIONS

Aneurysmal deterioration is an increasingly described complication of MFB implantation as a full root, with an incidence as high as 4.7%. Given the observed immune reaction and lack of occurrence in smaller (19-mm and 21-mm) valve sizes, inadequate pressure fixation of larger valves is a potential etiology. Patients with MFB require annual surveillance imaging, and consideration of this complication should factor into preoperative decision making because treatment mandates redo root replacement, which may not be feasible in high-risk patients.

Root replacement with stentless Freestyle bioprostheses for active endocarditis: a single centre experience

OBJECTIVES

Few studies have examined the use of stentless Freestyle bioprostheses in patients with active valve endocarditis (VE). The aim of this study was to evaluate outcomes of stentless Freestyle bioprostheses in patients undergoing full-root replacement.

METHODS

From February 2000 to June 2010, 180 patients with VE underwent cardiac surgery at our institution, of which 71 (39.5%) had prosthetic VE. Eighteen patients underwent full-root replacement with Freestyle bioprostheses: 3 patients (16%) had native aortic VE, 14 (78%) had aortic prosthetic VE and 1 (6%) had mitral and aortic prosthetic VE. Mean age was 66.7 ± 10.1, M/F: 6/12, mean logistic EuroSCORE 36.4 ± 21.6. Eight patients (42%) underwent concomitant procedures (two mitral valve replacements, three ascending aorta replacements, one coronary artery bypass grafting (CABG), one ventricular septal disease (VSD) repair, one CABG + ascending aorta + VSD repair).

RESULTS

Two patients (11%) died in-hospital. At the median follow-up of 24 months (range 1-113 months), no death occurred and freedom from reoperation was 87.5% (2 patients for aortic root pseudo-aneurysm at 1 and 23 months). All patients are in NYHA functional class I and have satisfactory echocardiographic data (EF 54.3 ± 8%, peak and mean trans-prosthetic gradients 12 ± 6.7 mmHg and 7.5 ± 3.6 mmHg) with 100% freedom recurrence of VE.

CONCLUSIONS

Our experience shows that root replacement with Freestyle stentless bioprostheses in patient with VE, is associated with low rates of early and mid-term mortality, good haemodynamic performance and low rates of valve-related morbidity as well as low recurrence of infection.

Composite freestyle stentless xenograft with Dacron graft extension for ascending aortic replacement

BACKGROUND

The present study was undertaken to evaluate clinical, hemodynamic, and morphologic results of composite stentless xenograft with polyethylene terephthalate fiber (Dacron; DuPont, Wilmington, DE) graft extension for combined replacement of the aortic valve, root, and ascending aorta.

METHODS

Between 1997 and 2008, 55 consecutive patients (33 men, 71 +/- 11 years) underwent ascending aortic replacement using Medtronic Freestyle with Dacron graft extension (DuPont). Indications included aneurysm (n = 31, 56%), dissection (n = 16, 29%), and endocarditis (n = 8, 15%). Associated procedures were performed in 25 patients (46%). Preoperative logistic EuroSCORE averaged 34% +/- 28%. Mean cardiopulmonary bypass and aortic cross-clamp times were 244 +/- 134 minutes and 162 +/- 69 minutes, respectively.

RESULTS

Clinical follow-up was 100% complete and averaged 2 +/- 3 years. Early mortality was 0% (n = 0) in patients with a preoperative EuroSCORE of less than 20 (n = 26, mean expected mortality, 13% +/- 5%) and 31% (n = 9) in those with preoperative logistic EuroSCORE of at least 20 (n = 29, mean expected mortality, 52% +/- 28%). One- and 3-year survival rates were 83% +/- 5% and 78% +/- 7%, respectively. No major thromboembolic or spontaneous bleeding events were recorded. One patient (2%) required late reoperation for prosthetic valve endocarditis. Echocardiographic follow-up showed no valve dysfunction and low mean transvalvular gradients (7 +/- 5 mm Hg). A 64-channel computed tomographic scan was performed in 33 patients at 32.4 +/- 34 months and revealed two small pseudoaneurysms in a single patient.

CONCLUSIONS

Composite Freestyle with Dacron graft extension appears to be a safe option for bioprosthetic replacement of the aortic root and tubular ascending aorta. However, long-term results using this composite graft will have to be determined.