Choice of prosthetic heart valve for surgical aortic or mitral valve replacement

INTRODUCTION — When heart valve replacement is warranted, a choice is made between transcatheter valve replacement and surgical valve replacement with a mechanical or bioprosthetic valve.

Choice of prosthesis for surgical valve replacement will be reviewed here. The discussion will focus on aortic or mitral valve replacement. The indications for valve replacement, assessment of risk of valve surgery, complications of prosthetic valves, management of patients with prosthetic valves, and choice of valve intervention prior to pregnancy are discussed separately. (See "Indications for valve replacement for high gradient aortic stenosis in adults" and "Natural history and management of chronic aortic regurgitation in adults" and "Chronic primary mitral regurgitation: General management" and "Estimating the risk of valvular procedures" and "Mechanical prosthetic valve thrombosis or obstruction: Clinical manifestations and diagnosis" and "Overview of the management of patients with prosthetic heart valves" and "Pregnancy and valve disease", section on 'Interventions prior to pregnancy' and "Rheumatic mitral stenosis: Overview of management", section on 'Indications for intervention'.)

The use of transcatheter bioprosthetic valves to treat native valve disease or to treat bioprosthetic valve structural failure is discussed separately. (See "Choice of intervention for severe calcific aortic stenosis" and "Surgical and investigational approaches to management of mitral stenosis", section on 'Transcatheter mitral valve replacement' and "Bioprosthetic valve thrombosis, thromboembolism, and obstruction: Management", section on 'Transcatheter intervention' and "Management and prognosis of surgical aortic and mitral prosthetic valve regurgitation", section on 'On transcatheter valve-in-valve implantation' and "Surgical and investigational approaches to management of mitral stenosis".)

PROSTHETIC VALVE TYPES — Surgical valve replacement is performed with mechanical or bioprosthetic valves. For most patients, a choice is made between a mechanical valve or a stented bioprosthesis [1,2]:

●Current mechanical options include bileaflet (eg, St. Jude, Carbomedics, and On-X valves) and low thrombogenicity single tilting disc valves (eg, Medtronic Hall) (figure 1).

Some earlier mechanical valve types were associated with greater risk of complications. Some studies have suggested that earlier tilting disc valve types (eg, Omniscience, Lillehei-Kaster, Bjork-Shiley Monostrut) were associated with increased risk of thromboembolism [2]. The earlier Bjork-Shiley convexo-concave single tilting disc valve was withdrawn from the market in 1986 due to reports of outlet strut fractures. The older caged ball valve (eg, Starr-Edwards) had unfavorable hemodynamic qualities and posed a high risk of thromboembolism and is no longer implanted.

●Bioprosthetic valve options include pericardial and xenograft (ie, from a different species; eg, porcine, bovine, or equine) valves (figure 2). Pericardial and xenograft valves may be stented or stentless. Bioprosthetic aortic valve options also include aortic homografts (ie, a section of aorta with its aortic valve intact from a human donor) and the Ross procedure (pulmonary autograft [the patient's own pulmonic valve] in the aortic position to replace a diseased aortic valve; the pulmonic valve is replaced with a pulmonary homograft). Stented bioprosthetic valves are the most common bioprosthetic option. (See 'Comparison of bioprosthetic valves' below.)

RECOMMENDATIONS FOR VALVE CHOICE

General approach — The choice of valve intervention (including a transcatheter versus surgical approach and valve repair or replacement) as well as the choice of type of prosthetic heart valve for surgical replacement should be a shared decision-making process with full disclosure of the indications for and risks of anticoagulant therapy and the potential need for and risk of reoperation and should account for the patient’s values and preferences [1]. The heart valve team (including cardiologists and cardiac surgeons) should consider the following factors which relate to valve durability, risk of thromboembolic and bleeding complications, and risk of mortality following valve replacement. (See 'Evidence on effect of valve choice on outcomes' below.)

●The following factors favor choice of a mechanical valve:

•For surgical aortic valve replacement, age <55 years

•For mitral valve replacement, age <70 years

•No contraindication to anticoagulation with a vitamin K antagonist (VKA)

-Low risk of bleeding

-Compliant patient

•Presence of an additional indication for anticoagulation (eg, an existing mechanical valve)

•High risk of morbidity/mortality with reintervention (eg, porcelain aorta)

●The following factors favor choice of a bioprosthetic valve:

•Patient’s life expectancy is shorter than the expected effective longevity of a bioprosthetic valve.

•Reoperation after mechanical valve thrombosis occurring despite good long-term control of anticoagulation and absence of structural defects.

•Anticoagulation with a VKA is contraindicated, cannot be managed appropriately, or is not desired by the patient. (See 'Future pregnancy' below.)

Newer oral antithrombotic agents such as the direct thrombin inhibitor dabigatran and factor Xa inhibitors (eg, rivaroxaban and apixaban) are not indicated in patients with prosthetic heart valves. Patients with prosthetic valves who require anticoagulation should receive a VKA (eg, warfarin), regardless of whether the anticoagulation is for the valve or another indication (eg, atrial fibrillation).

The 2020 American College of Cardiology/American Heart Association valvular heart disease guidelines and the 2021 European Society of Cardiology valvular heart disease guidelines include recommendations for choice of prosthetic valve [1,2].

End-stage kidney disease — Life expectancy in patients with end-stage kidney disease undergoing valve replacement is generally limited (eg, two-year survival rate of 39.7 percent [3]) and choice of mechanical versus bioprosthetic valve does not affect survival [3-5]. In patients with end-stage kidney disease, we favor bioprosthetic valves since these are associated with fewer valve-related complications than mechanical valves in this population [4].

Systematic reviews of observational studies have found no significant difference in survival in patients with end-stage kidney disease receiving bioprosthetic versus mechanical valves [4,5]. Case reports have raised concern for a potential risk of accelerated valve calcification and structural deterioration of bioprosthetic valves in patients with chronic kidney disease and secondary hyperparathyroidism [6-8]. However, a systematic review found that bleeding and thromboembolic events, which occur predominantly in patients receiving mechanical valves, occur much more frequently in this population than structural deterioration of bioprosthetic valves (bleeding in 0.9 percent, thromboembolism in 0.5 percent, and structural bioprosthetic deterioration in 0.07 percent) [4]. Combined valve-related complications (bleeding, thromboembolism, endocarditis, or structural valve deterioration) were less frequent in patients receiving bioprosthetic valves (odds ratio [OR] 0.4, 95% CI 0.2-0.7). (See "Valvular heart disease in patients with end-stage kidney disease", section on 'Aortic stenosis'.)

Future pregnancy — Choice of prosthetic valve for a patient requiring valve surgery prior to possible future pregnancy is discussed separately. In brief, the factors to be considered are the risk of pregnancy-related thromboembolic complications, the risk of anticoagulant therapy with mechanical valves, and the limited durability of bioprosthetic valves. (See "Pregnancy and valve disease", section on 'Interventions prior to pregnancy'.)

EVIDENCE ON EFFECT OF VALVE CHOICE ON OUTCOMES — The evidence below compares outcomes in patients undergoing surgical aortic and/or mitral valve replacement with bioprosthetic versus mechanical valves.

Limitation of available evidence — One challenge to applying available evidence to clinical practice is that long-term outcome data are not available for newer prosthetic valves (including most valves currently implanted), operative techniques, and transcatheter valve intervention. Comparisons of bioprosthetic valve series suggest that second generation porcine valves and pericardial valves are more durable than first generation porcine valves; newer models may yield even greater durability but data are limited [9]. Advances in cardiac surgery and perioperative care may reduce the risk of valve reoperation. The potential impact of future transcatheter replacement and valve-in-valve options as alternatives to reoperation to treat patients with structural valve degeneration is uncertain.

Mortality rates

Early mortality rates — Early (within 30 days) mortality rates have generally been similar after surgical valve replacement with a mechanical valve versus a bioprosthetic valve [10-12]. A study of 25,445 patients undergoing surgical prosthetic valve replacement in California from 1996 to 2013 found that 30-day mortality rates were similar for recipients of aortic bioprosthetic and mechanical valves (2.4 and 1.6 percent for patients aged 45 to 54 years; 1.6 and 1.7 percent for patients aged 55 to 64 years) [12]. Thirty-day mortality rates were also similar for recipients of mitral bioprosthetic and mechanical valves in the older age groups (4.0 and 3.7 percent for patients aged 50 to 69 and 7.2 and 8.1 percent for patients aged 70 to 79), but mortality rates were higher with bioprosthetic valves compared with mechanical valves in the 40 to 49 year age group (5.6 versus 2.2 percent; odds ratio 2.62, 95% CI 1.28-5.38). This study included an internal validation study to determine the accuracy of procedure codes; patient groups with high rates of misclassification were excluded.

By contrast, a Medicare-claims-based study found that among 66,453 patients undergoing aortic valve replacement (AVR), the mortality rate within 30 days of surgery was higher among patients receiving a mechanical valve compared with those receiving a bioprosthetic valve [13]. However, the significance of this finding is uncertain since the accuracy of coding was not validated against clinical records.

Late mortality rates — Randomized trials and observational studies comparing late mortality rates in patients with surgical bioprosthetic versus mechanical valves have yielded mixed results, with some but not all studies finding lower mortality rates with a mechanical valve in younger age groups [12,14].

The largest long-term study of patients with contemporary valves is the above cited observational study of 25,445 patients undergoing surgical valve replacement from 1996 to 2013 [12]. This study found age-dependent differences in long-term survival rates:

●Among patients receiving an AVR, receipt of a bioprosthetic valve was associated with a significantly higher 15-year mortality rate among patients aged 45 to 54 years old (30.6 versus 26.4 percent; hazard ratio [HR] 1.23; 95% CI 1.02-1.48) but not among patients 55 to 64 years old (36.1 versus 32.1 percent; HR 1.04; 95% CI 0.91-1.18) at the time of surgery. These relationships were not affected by adjustment for differences in baseline risk factors. In an analysis examining age as a continuous variable, the mortality benefit associated with a mechanical aortic valve applied to patients up to 53 years of age.

●Among patients receiving a mitral valve replacement, receipt of a bioprosthetic valve was associated with a significantly higher 15-year mortality rate among patients aged 40 to 49 years old (44.1 versus 27.1 percent at 15 years; HR 1.88; 95% CI 1.35-2.63) or 50 to 69 years old (50.0 versus 45.3 percent at 15 years; HR 1.16; 95% CI 1.04-1.30). Mortality was not significantly different between valve types among patients 70 to 79 years of age. These relationships were not affected by adjustment for differences in baseline risk factors. In an analysis examining age as a continuous variable, the mortality benefit associated with a mechanical mitral valve applied to patients up to approximately 68 years of age.

By contrast, an earlier meta-analysis of 32 observational studies with a total of 17,439 patients operated on between 1975 and 2002 found no difference in risk factor-adjusted overall mortality rate between bioprosthetic or mechanical AVR, regardless of age [14]. A limitation of this meta-analysis is that it included limited follow-up data for patients less than 60 years old receiving bioprosthetic valves.

The available randomized trial data are for valves that are now obsolete, patient numbers were limited, and results were not stratified by age. In a randomized trial including 575 patients (of which >90 percent of patients were ≤70 years old) undergoing valve replacement between 1977 and 1982, survival at 15 years was higher with a mechanical aortic valve than with a bioprosthetic aortic valve (34 versus 21 percent); by contrast, survival was similar after mechanical or bioprosthetic mitral valve replacement (19 versus 21 percent) [15]. By contrast, another randomized trial including 541 patients (with mean age 54 at time of valve replacement) operated on between 1975 and 1979 found no difference in mortality rates at 20 years in patients receiving Bjork-Shiley or porcine prostheses (75 versus 77 percent) [16].

In older patients (eg, 65 years and older), long-term survival with a bioprosthetic valve has been reported as similar to or slightly better than that with a mechanical valve (in the aortic or mitral position). Although a large Medicare-claims-based study found a slight survival benefit in patients receiving bioprosthetic aortic valves compared with those receiving mechanical aortic valves [17], a later report using Medicare claims linked to clinical data for risk adjustment and treatment assessment found similar long-term mortality rates in patients receiving bioprosthetic versus mechanical aortic valves [18].

Valve durability — Mechanical valves are more durable than bioprosthetic valves, as demonstrated by randomized trials and also seen in observational studies [10,12,15-19]. Structural valve degeneration is a much more frequent cause of primary valve failure than valve obstruction (thrombotic or nonthrombotic). Bioprosthetic structural valve degeneration leads to significantly higher rates of reoperation in patients receiving these valves. While structural valve degeneration is the major reason for prosthetic valve reoperation, rates of valve reoperation do not fully capture the risk of structural valve degeneration since some patients with significant structural valve deterioration are not deemed candidates for reoperation due to high risk [14].

Effect of age — The rate of bioprosthetic structural valve deterioration is lower in older patients [12,15,19-22]. In addition, older patients generally have shorter anticipated survival during which they are at risk for requiring replacement of a deteriorated bioprosthetic valve. The lower rate of valve failure requiring valve reoperation in older adults is due at least in part to decreased activity in older patients.

The 15-year risk of bioprosthetic structural deterioration is 50 percent for patients 20 years old, 30 percent for patients 40 years old, and <10 percent for patients 70 years old [1,23,24].

While young patients are generally more likely to require valve reoperation than older patients, evidence is mixed as to how the risks associated with reoperation (as compared with risks of long-term anticoagulation with a mechanical valve) impact overall long-term survival, as discussed above. (See 'Mortality rates' above.)

Incidence of reoperation — As a consequence of the age-dependent risk of bioprosthetic structural valve deterioration, the incidence of prosthetic valve reoperation is significantly higher for bioprosthetic valves compared with mechanical valves, and younger patients require reoperation sooner than older patients. As an example, in an observational study, the cumulative rates of reoperation at 15 years for patients aged 45 to 54 years with aortic bioprosthetic valves and mechanical valves were approximately 21 and 8 percent [12]. The cumulative rates of reoperation for patients aged 55 to 64 years at 15 years with aortic bioprosthetic valves and mechanical valves were approximately 17 and 7 percent. Significantly higher rates of reoperation with bioprosthetic valves compared with mechanical valves were also seen with mitral prostheses, particularly among younger patients.

Risks associated with reoperation — Surgical replacement of a prosthetic valve is associated with significant risk of early mortality (eg, 30-day mortality risk of 7 percent after aortic valve reoperation and 14 percent after mitral valve reoperation [12]). The individualized risk of a reoperation should be considered. The morbidity and mortality associated with valve reoperation is higher in some patient populations, such as those with coronary artery bypass grafts (CABG). Retrospective data indicate that operative mortality rates are higher for aortic or mitral valve replacement with pre-existing CABG and are also higher than for combined valve replacement and CABG [25-27]. In a patient with a patent internal mammary artery (IMA) graft, valve surgery poses a potential risk of IMA graft injury and myocardial infarction [28].

The increased risk associated with valve reoperation in a patient following CABG may favor implantation of a mechanical valve in patients requiring concurrent valve replacement and CABG. However, the emerging use of treating bioprosthetic valve degeneration with a transcatheter valve-in-valve procedure may offer patients an alternative to repeat surgical valve replacement. Currently, there are limited data on the long-term durability of this approach, so strong recommendations are not possible. However, this potential option to treat possible later bioprosthetic valve structural valve deterioration should be taken into consideration when deciding on the type of surgical valve, in conjunction with other factors, including patient age and preferences.

Bleeding complications — Bleeding is a common problem in patients with prosthetic heart valves [10,14-16,18,29-31]. The risk of bleeding is generally higher in patients with mechanical valves [12,15,16,18,29,30], due to the need for indefinite long-term anticoagulation to avoid thrombotic complications. By contrast, anticoagulation is suggested for patients with mitral or aortic bioprosthetic valves for only the first three months following valve replacement, unless there is an additional risk factor such as atrial fibrillation. (See "Antithrombotic therapy for mechanical heart valves".)

As an example, in the Veterans Affairs Cooperative Study, 575 patients were randomly assigned to therapy with a mechanical or bioprosthetic valve [29]. The 11-year probability of bleeding was significantly greater with mechanical valves (42 versus 26 percent). A similar result at 12 years (19 versus 7 percent) was noted in another controlled trial [30].

Risk of thrombotic and thromboembolic complications — The risk of prosthetic valve thrombosis is higher in patients with mechanical valves compared with patients with bioprosthetic valves, although data are limited [1]. The risk of thromboembolic complications is generally similar or lower in patients with bioprosthetic valves compared with that in patients with a mechanical valve treated with anticoagulation. In some patient groups, the risk of stroke among patients treated with standard antithrombotic therapy may be lower with a bioprosthetic valve than with a mechanical valve. In an example from an observational study, the cumulative risk of stroke among patients 45 to 54 years of age undergoing AVR was significantly lower among those with a bioprosthetic valve compared with those with a mechanical valve (approximately 10 versus 16 percent at 15 years; HR 0.64; 95% CI 0.46-0.86) [12]. Similarly, among patients undergoing mitral valve replacement, the cumulative risk of stroke was significantly lower among patients 50 to 69 years of age but not in other age groups.

Risk of endocarditis — During the first postoperative year, infection generally occurs with equal frequency on mechanical and bioprosthetic devices. During long-term follow-up, rates of endocarditis with bioprosthetic valves are similar to or slightly higher than with mechanical valves. (See "Prosthetic valve endocarditis: Epidemiology, clinical manifestations, and diagnosis".)

Evidence comparing specific valve types — Limited evidence is available comparing outcomes with specific types of mechanical valves or specific types of bioprosthetic valves.

Comparison of mechanical valves — A limitation of the published data on valves is that most long-term studies involved valve prostheses that are no longer being implanted. The four mechanical heart valves with the largest implant records are the Starr-Edwards ball-in-cage valve (no longer implanted), the Medtronic-Hall single tilting disc valve, the St. Jude bileaflet valve, and the Carbomedics bileaflet valve [32]. Limited retrospective data on the last three valves suggest no definite difference in outcomes [33-35].

A randomized trial compared clinical outcomes following St. Jude versus Carbomedics aortic and/or mitral valve replacement in 485 patients (288 aortic valve only replacements) [36]. No significant differences were observed in 10-year rates of survival (65 and 66 percent, respectively) or freedom from valve-related complications (46 and 52 percent).

Comparison of bioprosthetic valves — Limited data are available comparing various bioprosthetic valve types. Among patients who receive a bioprosthesis, pericardial and porcine prostheses have similar durability data [37-41]. An observational study comparing outcomes for patients receiving various types of bioprosthetic aortic valve types (stented or stentless xenograft, homograft, and Ross procedure) found similar perioperative mortality and similar rates of mortality and freedom from reoperation at seven years [42].

Stentless valves are more complicated to implant than stented valves but have the potential advantage of having larger effective orifice areas, although an improvement in outcomes has not been found [43] (see 'Prosthetic valve-patient mismatch' below). More data are needed regarding the risk of early and late stentless valve deterioration, particularly the potential risk of accelerated deterioration of stentless valves, particularly in younger patients [44].

Homograft aortic valves are most often used for treatment of native valve or prosthetic valve endocarditis because the homograft is supplied as a composite valve, aortic root, and part of the anterior mitral leaflet. This additional tissue may be used to reconstruct the areas adjacent to the valve, which is helpful if the infection has extended into the annulus, basal septum, or base of the mitral valve. A disadvantage of homograft valves is the greater technical difficulty of implantation. In addition, fibrosis (involving the adjacent pulmonary artery) and calcification (frequently involving the coronary button reattachment) of the composite root and valve make it more difficult to perform repeat surgical intervention, which may be required on long-term follow-up.

Aortic valve and root replacement with a valved conduit is an alternative to a homograft and may provide comparable or better results. A randomized trial compared xenograft stentless (Freestyle) aortic bioprosthetic (porcine) root versus homograft in 166 patients undergoing total aortic root replacement [45]. Eight-year survival was similar (80 versus 77 percent), but freedom from need for reoperation at eight years was higher after Freestyle root replacement (100 versus 90 percent).

Ross procedure — The Ross procedure is an alternative to AVR with a mechanical valve or a pericardial or xenograft bioprosthesis. It involves replacing the aortic valve with a pulmonic valve autograft and right-sided reconstruction with an aortic or pulmonary homograft [46,47]. The pulmonary autograft in the aortic position provides excellent hemodynamics at rest and with maximum exercise; however, there may be a moderately high gradient across the homograft in the pulmonary valve position [48].

Use of the Ross procedure in adults is controversial and the procedure is performed at only a few experienced centers. Reasons include its technical complexity; complications with both the aortic autograft and the pulmonic homograft, with long-term risk of requiring reoperation of 20 percent or more [49-51]; and the availability of simpler and effective alternatives (ie, mechanical valves and bioprosthesis, including stentless bioprosthetic valves). Even at experienced centers, use of this procedure has waned since the 1990s.

Given its limitations, the pulmonic autograft procedure is predominantly performed in children, as the autograft aortic annulus and valve may have the capacity to grow. It has also been performed at a limited number of experienced centers in selected adults less than 50 years of age such as athletes or other young patients in whom anticoagulation is contraindicated and for whom optimal hemodynamics are desired (eg, a woman contemplating pregnancy). (See "Bicuspid aortic valve: Preconception and pregnancy care".)

OTHER CONSIDERATIONS

Availability of an experienced surgical team — Some biological aortic valve options are technically more challenging than others (Ross procedure >aortic homografts >stentless aortic valve replacement [AVR] >stented AVR). Also, reoperations after certain biological valves (eg, homographs) are technically more challenging than after implantation of standard bioprosthetic valves. (See 'Comparison of bioprosthetic valves' above.)

Concurrent aortic surgery — The potential need for concurrent aortic surgery should be considered in patients with dilated aortic root or ascending aorta, including patients with bicuspid aortic valve who are at risk for aortic aneurysm and aortic dissection. Monitoring and indications for concomitant aortic root replacement are discussed separately. (See "Bicuspid aortic valve: General management in adults".)

Prosthetic valve-patient mismatch

Definitions — Prosthetic valve-patient mismatch (PPM) is considered to be present when the effective orifice area (EOA) indexed for body surface area (BSA) is less than that of a normal human valve [52]. PPM is considered not clinically significant if the indexed EOA is >0.85 cm²/m², moderate if >0.65 to ≤0.85 cm²/m², and severe if ≤0.65 cm²/m² [53]. The main clinical concern is the presence of a high transvalvular gradient (ie, functional stenosis) through a normally opening valve.

Frequency and effect on outcomes — PPM appears to be more likely with bioprosthetic valves. This was illustrated in a review of 1400 consecutive patients who underwent bioprosthetic or mechanical AVR [54]. PPM, defined as an indexed EOA <0.75 cm²/m², was present in 51 percent of patients with bioprosthetic valves compared with 11 percent in those with mechanical valves. Stented tissue valves are generally associated with smaller EOAs, due to the space occupied by the supporting stents. This may be particularly important in patients with a small aortic annulus who are at risk for patient-prosthesis mismatch [55].

PPM was associated with adverse early- and long-term outcomes in some studies but multivariate analyses of long-term outcomes have yielded conflicting results [52,56-60]. PPM was an independent predictor of risk of late mortality in some studies [56-58], but not in others [59,60]. As an example, a study of 3343 patients undergoing AVR found that survival was significantly worse among those with severe PPM as compared with those with no PPM (22.1 percent versus 38.1 percent at 15 years) [60].

Potential explanations for discrepancies among studies on the impact of PPM on outcomes include differing criteria for PPM as well as a variety of clinical factors that may influence the effect of PPM on outcomes. These factors include:

●Age – Severe PPM was associated with increased mortality in younger patients (<60 or <70 years old) but not in older patients in two series [54,61]. A potential contributing factor is that younger patients are more active, which leads to higher stroke volumes and therefore higher transvalvular gradients.

●Body size – PPM identified by EOA indexed to BSA is associated with increased mortality in average-sized patients but not in patients with obesity or small body size. One potential explanation for the lack of apparent impact of PPM in large and small patients is that the indexed EOA (EOA divided by BSA) may not accurately reflect the degree of mismatch in these patients.

•In a series of 2576 patients, severe PPM had no impact in patients with obesity but was associated with mortality in patients with body mass index <30 kg/m² [61].

•In a report of 1400 patients, moderate PPM was not important in small patients (BSA <1.7 m²) but was associated with mortality among average-sized patients (BSA 1.7 to 2.1 m²) with either bioprosthetic or mechanical valves and among large patients (BSA >2.1 m²) with mechanical valves [54].

●Reduced left ventricular ejection fraction (LVEF) – The presence of left ventricular systolic dysfunction (LVEF <40 to 50 percent) appears to confer susceptibility to adverse early and late outcomes in patients with PPM [53,61,62].

Strategies to avoid prosthetic valve-patient mismatch — Every effort should be made to minimize the likelihood of severe PPM. The risk of PPM is reduced by selecting a prosthetic valve with an adequate indexed orifice area given the patient’s annular dimension and body size. Protocols have been suggested to attain an EOA at rest of >0.75 to 0.85 cm²/m² (ideally >0.85 cm²/m²) [52]. Annulus enlargement or a stentless valve root conduit is suggested if the anticipated prosthesis-patient ratio is low (eg, <0.65 cm²/m² BSA) [2]. In one series, aortic root enlargement lowered the rate of moderate to severe PPM from 17 to 2.5 percent [63]. Among patients who have severe mismatch, reoperation may be required with the same indications as those for native valve stenosis [52,56].

While stentless valves generally provide larger EOAs than stented valves, they are used selectively when needed since stentless valves are more technically challenging to implant. Randomized trials have found similar intermediate (one- to five-year) regression of left ventricular mass and clinical outcomes with stented and stentless valves [64-66], though two trials noted greater increase in indexed EOA in the stentless group [65,66] and one trial identified earlier regression of left ventricular mass in the stentless group [66].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Cardiac valve disease".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: Aortic stenosis (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Contemporary mechanical heart valves include bileaflet and tilting disc valves. Types of surgical bioprosthetic heart valves include stented valves (porcine and pericardial), stentless valves (porcine, bovine, and equine), as well as aortic homografts and human autografts (Ross procedure). Transcatheter bioprosthetic valves also are an option for valve-in-valve procedures to treat bioprosthetic structural valve failure and for transcatheter intervention to treat native aortic valve disease. (See 'Prosthetic valve types' above.)

●The choice of valve intervention (including a transcatheter versus surgical approach and valve repair or replacement) as well as choice of the type of prosthetic heart valve for surgical replacement should be a shared decision-making process with full disclosure of the indications for and risks of anticoagulant therapy and the potential need for and risk of reoperation and should account for the patient’s values and preferences. (See 'Recommendations for valve choice' above.)

●Choice of surgical prosthetic valve is based upon key considerations, including the requirement of lifelong anticoagulation with mechanical valves, risk of structural valve deterioration and associated risk of reoperation with bioprosthetic valves, and impact on long-term survival based upon patient age. (See 'Recommendations for valve choice' above and 'Evidence on effect of valve choice on outcomes' above.)

•The following factors favor choice of a mechanical valve:

-For surgical aortic valve replacement, age <55 years.

-For mitral valve replacement, age <70 years.

-No contraindication to anticoagulation with a vitamin K antagonist (VKA).

-Presence of an additional indication for anticoagulation (eg, an existing mechanical valve).

-High-risk of morbidity/mortality with reintervention (eg, porcelain aorta).

•The following factors favor choice of a bioprosthetic valve:

-Patient’s life expectancy is shorter than the expected effective longevity of a bioprosthetic valve.

-Reoperation after mechanical valve thrombosis occurring despite good long-term control of anticoagulation and absence of structural defects.

-Anticoagulation with a VKA is contraindicated, cannot be managed appropriately, or is not desired by the patient. (See 'Future pregnancy' above.)

●The impact of surgical prosthetic valve choice on long-term survival may be age-dependent:

•In younger patients (patients less than 55 years old with aortic valves or less than 70 years old with mitral valves), long-term survival may be higher with a mechanical valve than with a bioprosthetic valve. (See 'Late mortality rates' above.)

•In older patients, long-term survival with a bioprosthetic valve may be similar to or slightly better than that with a mechanical valve. (See 'Late mortality rates' above.)

●Life expectancy in patients with end-stage kidney disease undergoing valve replacement is generally limited and choice of mechanical versus bioprosthetic valve does not affect survival. In patients with end-stage kidney disease, we favor bioprosthetic valves since these are associated with fewer valve-related complications than mechanical valves in this population. (See 'End-stage kidney disease' above.)

●Prosthetic valve-patient mismatch (PPM) was an independent predictor of mortality in some studies, but not in others. Since it can cause clinically significant obstruction, every effort should be made to minimize the likelihood of severe PPM. Strategies for patients with small aortic roots include aortic root enlargement or use of a stentless valve root conduit. (See 'Prosthetic valve-patient mismatch' above.)

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges William Gaasch, MD (deceased), who contributed to an earlier version of this topic review.