1. The ischemic and CPB times are significantly longer for implantation of a stentless bioprosthetic valve (∼20 minutes; level A).
2. No difference has been shown in total time in the operating room (level B), ICU and hospital LOS (level A).
Consensus Conference Recommendations
To date all published RCTs of stentless bioprosthesis valves have been inserted in the subcoronary configuration. The consensus panel agreed upon the following statements and recommendations in patients undergoing aortic valve replacement (Table 3):
1. Stentless and stented valves both provide an excellent valve substitute for aortic valve disease (class I, level A).
2. In certain situations, the early superior hemodynamic performance of stentless bioprosthesis offers advantages over stented valves (class IIa, level A).
Because there were no RCT comparing subcoronary stentless prosthetic valve and root replacement, the following recommendations are derived from expert opinion:
1. In the absence of aortic root disease and with an annulus greater than or equal to 21 mm, either stentless or stented valves are acceptable alternatives for the majority of patients when a current (second or third) generation bioprosthesis is indicated (class I, level C).
2. In the presence of an aortic annulus <21 mm, the use of a freestanding bioprosthetic root can be considered as an alternative to enhanced diameter stented bioprosthesis or a root enlargement procedure (class I, level C).
All randomized trials inserted the stentless bioprosthetic valves in the subcoronary configuration. Although none of the important clinical outcomes (prosthesis patient mismatch, valve complications, CVA, acute myocardial infarction, atrial fibrillation, A-V heart block, permanent pacemaker, thromboembolic events, heart failure, renal failure, wound infection, bleeding complications, endocarditis, and mortality) were significantly impacted by the insertion of stentless versus stented valves, there were a number of intermediate hemodynamic and cardiac parameters (mean/peak Ao gradient, EOAI, and LVMI) that were improved with stentless valves. On the other hand, the ischemic and CPB times are significantly longer for implantation of a stentless bioprosthetic valve (∼20 minutes) with no impact in total operating room time, ICU and hospital LOS.
Strengths and Limitations
A notable strength of this consensus statement is its reliance on the evidence base, with comprehensive consideration of benefits, risks, and resource-related issues. The methodology undertaken and recommendations provided by this consensus conference are in agreement with current recommendations for developing consensus statements and guidelines.12,13 Clinicians tend to overestimate the effectiveness of new interventions, especially if the intervention in question rests within the realm of their expertise, unless they objectively take into account a systematic review of the evidence.15 There is a tendency for group decision-making processes to experience “regression to the mean” or a group-think effects, whereby compromises are made in recommendations to come closest to pleasing all members of the panel, even for issues that start off greatly polarized. To mitigate these risks, experts in evidence-based methodology and health technology assessment from within and outside of the surgical field were invited to facilitate the discussion and to ensure the best available evidence was the focus for discussion rather than opinions or political charges. This process has been similar to other ISMICS consensus conferences conducted in recent years.16–19
A few important limitations in the current literature were observed by the panel and were carefully balanced when addressing the question if stentless valve improves clinical and resource utilizations in compared with stented valve:
1. Insufficient data reported follow-up for assessment of long term performance inclusive of durability between stentless and stented bioprosthetic valve.
2. Overlapping databases found with discrepancy in outcomes in some publications.
3. Publications often do not follow STS/AATS/EACTS guidelines (96′) in reporting morbidity outcomes.
4. Drop out in trials were not explicitly accounted for in most studies.
5. There was a bias toward survivor and healthy patients with regard to echocardiographic studies.
6. Important subgroups of patients were not adequately studied, ie, ventricular dysfunction, elderly, abnormal BMI, and small aortic roots.
7. Insufficient published reports on clinical relevant outcomes such as AMI, renal failure, neurologic injury, quality of care, and prosthesis patient mismatch.
8. Insufficient published data on third generation (diameter enhanced) stented bioprostheses compared with stentless bioprosthetic valves.
9. Insufficient published data to differentiate the relative outcomes across subtypes of stentless compared with subtypes of stented bioprosthetic valves.
Aortic Root Configuration of Stentless Bioprosthetic Valve
As pointed out in the meta-analysis that all randomized trials inserted the stentless bioprosthetic valves in the subcoronary configuration, the consensus panel discussed and consented as expert opinions on the following:
* Stentless bioprostheses have been used in a freestanding root configuration for patients with aortic root diseases such as aneurysm, dissection, Marfan syndrome, and native valve endocarditis (level C).
* This particular configuration is also useful for complex redo aortic valve surgery, eg, prosthetic valve endocarditis, reoperative homograft replacement (level C).
* Root configuration for elective AVR without root disease is another alternative for surgeons with experience in aortic root replacement (level C).
* For the surgical treatment of the small aortic root (<21 mm diameter), the stentless bioprostheses in the freestanding root configuration can be considered as an alternative to aortic annulus enlargement (Nicks or Manougian procedures), or 3rd generation stented (optimal tissue-stent relationship for diameter enhancment, low (<2 mm Hg) or zero pressure guataraldehyde fixation and treatment for the reduction of calcification), Carpentier Edwards PERIMOUNT Magna, Medtronic Mosaic Ultra, St. Jude Medical Epic Supra, Sorin Mitroflow and Sorin Freedom and Sorin Freedom Solo (level C).
Indications for Subcoronary Implantation: (Level C)
The subcoronary configuration may be considered for (a) simple native valve endocarditis affecting leaflets only and for (b) small aortic roots where avoidance of a late calcified bioprosthetic root is considered desirable.
Contraindications for Subcoronary Implantation: (Level C)
1. Severe calcification of the aortic root may be a contraindication to the use of a stentless bioprostheses.
2. The surgeon must give consideration to a disparity between the diameter of the annulus versus the sinotubular junction. If this is >10% a subcoronary configuration is not advised.
3. In the presence of bicuspid valve disease with a dilated aortic root, it may be advisable to buttress the sinotubular junction to prevent subsequent dilatation.
4. As a potential consequence of aging and dilatation of the aortic root, buttressing of the sinotubular junction may also be considered.
5. In the presence of abnormally placed coronary ostia eg, 180 degrees apart, a subcoronary implant is ill advised.
Statements on Future Research
Future investigation must also evaluate the long-term survival in conventional aortic valve replacement matched in age/gender. This may relate to the timing of aortic valve intervention, in relation to the natural history of the disease and the status of systolic and diastolic function at the time of the intervention; correlated with postoperative hemodynamic, coronary flow evaluation, durability of the bioprostheses and quality of life. The hemodynamic performance should assess both systolic and diastolic performance to at least 10 years. The attainment of a normal cardiac output is dependent upon restoration of diastolic function which may depend upon adequate resolution of left ventricular hypertrophy. The assessment of durability of stentless bioprostheses requires at least 15 years evaluation. Studies should update the existing RCT in long-term follow-up, and benchmark for assessment of transcathether technology and sutureless prostheses.
The authors acknowledge Ms. Aurelie Alger and Ms. Elizabeth Chouinard for their professional assistance in organizing the consensus conference; Dr. Guyan Wang, Dr. Kathy Fang, Dr. Myoung Kim, and Dr. Ling Pei for their expert data extraction; Ms. Jennifer Podeszwa-deOliviera and Ms. Karla VanKessel for their services in facilitating the literature searches and retrieval.
1.Levy D, Garrison RJ, Savage DD, et al. Prognostic implications of echocardiographically determine left ventricular mass in the Framingham heart study. N Engl J Med.
2.Sharma UC, Barenbrug P, Pokharel S, et al. Systematic review of the outcome of aortic valve replacement in patients with aortic stenosis. Ann Thorac Surg.
3.Kunadian B, Vijayalakshmi K, Thornley AR, et al. Meta-Analysis of valve hemodynamics and left ventricular mass regression for stentless versus stented aortic valves. Ann Thorac Surg.
4.Raja SG, MacArthur KJ, Pollock JC. Impact of stentless aortic valves on left ventricular function and hypertrophy: current best available evidence. J Card Surg.
5.Kallikourdis A, Jacob S. Is a stentless aortic valve superior to conventional bioprosthetic valves for aortic valve replacement? Interact Cardiovasc Thorac Surg.
6.Sackett DL, Straus SE, Richardson WS, et al. Evidence-Based Medicine: How to Practice and Teach EBM.
2nd ed. London: Churchill Livingstone; 2000.
7.Cheng D, Pepper J, Martin J, et al. Stentless versus stented bioprosthetic aortic valves: a systematic review and meta-analysis of controlled trials. Innovations.
8.Colditz GA, Miller JN, Mosteller F. How study design affects outcomes in comparisons of therapy. I. Medical. Stat Med.
9.Moher D, Pham B, Jones A, et al. Does quality of reports of randomized trials affect estimates of intervention efficacy reported in meta-analyses? Lancet.
10.Milz S, Colditz GA, Mosteller F. How study design affects outcomes in comparisons of therapy. II. Surgical. Stat Med.
11.Schulz KF, Chalmers I, Hayes RJ, et al. Empirical evidence of bias. Dimensions of methodological quality associated with estimates of treatment effects in controlled trials. JAMA.
12.Shekelle PG, Woolf SH, Eccles M, et al. Clinical guidelines: developing guidelines. BMJ.
13.Shiffman RN, Shekelle P, Overhage M, et al. Standardized reporting of clinical practice guidelines: a proposal from the conference on guideline standardization. Ann Intern Med.
14.Bakhtiary F, Schiemann M, Dzemali O, et al. Stentless bioprostheses improve postoperative coronary flow more than stented prostheses after valve replacement for aortic stenosis. J Thorac Cardiovasc Surg.
15.Sackett DL. Rules of evidence and clinical recommendations on the use of antithrombotic agents. Chest.
16.Puskas J, Cheng D, Knight J, et al. Off-pump versus conventional coronary artery bypass grafting: a meta-analysis and consensus statement from the 2004 ISMICS consensus conference. Innov: Technol Tech Cardiothorac Vasc Surg.
17.Allen K, Cheng D, Cohn W, et al. Endoscopic vascular harvest in coronary artery bypass grafting surgery: a consensus statement of the International Society of Minimally Invasive Coronary Surgery (ISMICS). Innov: Technol Tech Cardiothorac Vasc Surg.
18.Diegeler A, Cheng D, Allen K, et al. Transmyocardial laser revascularization: a consensus statement of the International Society of Minimally Invasive Cardiothoracic Surgery (ISMICS) 2006. Innov: Technol Tech Cardiothorac Vasc Surg.
19.Downey R, Cheng D, Kernstine K, et al. Video-assisted thoracic surgery in lung cancer resection: a consensus statement of the International Society of Minimally Invasive Cardiothoracic Surgery (ISMICS) 2007. Innov: Technol Tech Cardiothorac Vasc Surg.
Keywords:© 2009 Lippincott Williams & Wilkins, Inc.
Consensus statements; Aortic valve surgery; Stentless valve surgery; Stentless valve surgery