Prosthetic valve type for patients undergoing aortic valve replacement: a decision analysis

Mechanical Versus Bioprosthetic Aortic Valve Replacement in Patients Undergoing Bentall Procedure

BACKGROUND

The widely used Bentall procedure is the criterion standard treatment for aortic root pathology. Studies comparing the long-term outcomes of bioprosthetic and mechanical valves in patients undergoing the Bentall procedure are limited.

METHODS AND RESULTS

Patients who underwent the Bentall procedure with a bioprosthetic or mechanical valve between 2001 and 2018 were identified from Taiwan's National Health Insurance Research Database. The primary outcome of interest was all-cause mortality. Inverse probability of treatment weighting was performed to compare the 2 prosthetic types. In total, 1052 patients who underwent the Bentall procedure were identified. Among these patients, 351 (33.4%) and 701 (66.6%) chose bioprosthetic and mechanical valves, respectively. After inverse probability of treatment weighting, no significant differences in the in-hospital mortality (odds ratio, 0.96 [95% CI, 0.77-1.19]; P=0.716) and all-cause mortality (34.1% vs. 38.1%; hazard ratio, 0.90 [95% CI, 0.78-1.04]; P=0.154) were observed between the groups. The benefits of relative mortality associated with mechanical valves were apparent in younger patients and persisted until ≈50 years of age.

CONCLUSIONS

No differences in survival benefits were observed between the valves in patients who underwent the Bentall procedure. Additionally, bioprosthetic valves may be a reasonable choice for patients aged >50 years when receiving the Bentall procedure in this valve-in-valve era.

Evolving technology: the TRIFLO tri-leaflet mechanical valve without oral anticoagulation: a potential major innovation in valve surgery

The aortic valve is the most frequently diseased valve and aortic stenosis (AS) is the most prevalent valvular heart disease in developed countries. The diseased native aortic valve can be replaced by either a biological or mechanical valve prosthesis. The main concerns relate to durability, the need for oral anticoagulants and the incidence of complications related to this medication. Experimental, computational and biomolecular blood flow studies have demonstrated that the systolic forward flow but also the reverse flow phase at the end of the systole and leakage during the diastolic phase is mainly responsible for platelet activation and thrombosis. Better design of mechanical prosthetic heart valves must ensure smooth closing during flow deceleration and must eliminate high-shear hinge flow during diastole to prevent life-threatening thrombosis. A novel tri-leaflet valve should combine the favorable hemodynamics and the durability of existing mechanical heart valves and eliminate the less favorable characteristics, including the extremely rapid closing. In this paper, we discuss some issues of current mechanical heart valve prostheses and present a new valve design with the potential for significant innovation in the field. The TRIFLO Heart Valve, is a rigid, three-leaflet central flow heart valve prosthesis consisting of an alloyed titanium housing, and three rigid polymer (PEEK) cusps. This valve has a physiological operating mode. During the forward flow phase, the intraventricular pressure opens the leaflets so that blood can freely flow through with little obstruction, and with the deceleration of the blood flow, the leaflets close early and smoothly, minimizing blood flow regurgitation, blood cell damage, and activation of the coagulation cascade. Pre-clinical studies have shown pretty favorable results and a first-in-man study should start very soon.

A systematic review of the cost-effectiveness of heart valve replacement with a mechanical versus biological prosthesis in patients with heart valvular disease

Heart valve disease (HVD) affects 2.5% of the US population and one million individuals aged 65 years and older in the UK. Given its burden, the aim of the present review was to assess the cost-effectiveness of heart valve replacement with mechanical versus biological prosthesis in HVD patients. We performed a systematic search in various electronic databases from January 1990 to June 2019. Five out of 542 articles were entered into the study, from which 2 papers were subsequently excluded not meeting the minimum number of items of the CHEERS checklist. Quality-Adjusted Life Year, Life Years Gained, and the Incremental Cost-Effectiveness Ratio (ICER) regarding the type of replaced heart valve were extracted and reported. Studies were conducted in three different countries (Iran, France, and USA). ICER ranged from $1253 in Iran to €54,634 in France. Survival rate of mitral mechanical versus biological valves at 10 and 20 years was 72.9% versus 76.0% and 51% versus 30%, respectively. Survival rate at 20 years in patients undergoing atrial valve replacement was 20%. Ten- and 20-year death rates for biological valves were higher with respect to mechanical prosthesis (15.5% versus 8.4% at 10 years), with this difference becoming more relevant at 20 years (36.9% versus 13.9%). Due to higher ICER, mortality rate, and lower success rates in the long term for biological prostheses compared to mechanical ones, these appear to be more suitable for older patients (aged ≥ 70 years).

Recurrent Hemorrhagic Conversion of Ischemic Stroke in a Patient with Mechanical Heart Valve: A Case Report and Literature Review

The authors present a unique case of recurrent stroke, discovered to be secondary to hemorrhagic conversion of microemboli from a mechanical aortic valve despite anticoagulation with Coumadin. The complexity of this case was magnified by the patient’s young age, a mechanical heart valve (MHV), and a need for anticoagulation to maintain MHV patency in a setting of potentially life-threatening intracranial hemorrhage. Anticoagulant and antiplatelet therapy are risk factors for hemorrhagic conversion post-cerebral ischemia; however, the pathophysiology underlying endothelial cell dysfunction causing red blood cell extravasation is an active area of basic and clinical research. The need for randomized clinical trials to aid in the creation of standardized treatment protocol continues to go unmet. Consequently, there is marked variation in therapeutic approaches to treating intracranial hemorrhage in patients with an MHV. Unfortunately, patients with an MHV are considered at high thromboembolic (TE) risk, and these patients are often excluded from clinical trials of acute stroke due to their increased TE potential. The authors feel this case represents an example of endothelial dysfunction secondary to microthrombotic events originating from an MHV, which caused ischemic stroke with hemorrhagic conversion complicated by the need for anticoagulation for an MHV. This case offers a definitive treatment algorithm for a complex clinical dilemma.

Choice of prosthetic heart valve in a developing country

Mechanical prostheses and stented xenografts (bioprosthesis) are most commonly used substitutes for aortic and mitral valve replacement. The mechanical valves have the advantage of durability but are accompanied with the risk of thromboembolism, problems of long-term anticoagulation, and associated risk of bleeding. In contrast, bioprosthetic valves do not require long-term anticoagulation, but carry the risk of structural valve degeneration and re-operation. A mechanical valve is favoured in young patients (<40 years) if reliable anticoagulation is ensured. In elderly patients (>60 years), a bioprosthesis is a suitable substitute. In middle-aged patients (40-60 years), risk of re-operation in a bioprosthesis is equal to that of bleeding in a mechanical valve. Traditionally, a bioprosthesis is opted in patients with limited life expectancy. Calculation of life expectancy, based solely upon chronological age, is erroneous. In developing countries, the calculated life expectancy is much lower than that of Western population, hence age related Western cut-offs are not valid in developing countries. Besides age, cardiac condition of the patient, systemic illnesses, socio-economic status, gender and geographical location also decide the life expectancy of the patients. Selection of the prosthetic valve substitute should be based on: aspiration of the patient, life expectancy, socio-economic and educational background, occupation of the patient, availability, cost, monitoring of anti-coagulation, monitoring of valve function and other valve related complications, and possibility of re-operation.

Special report: 26-year durability of a bioprosthesis implanted in a 21-year-old patient

The choice of prosthetic heart valve type is largely dependent upon patient's age at implantation and on what, in his eyes, seems more pertinent: avoidance of complications associated with anticoagulation of mechanical valves or structural valve deterioration of bioprosthetic valves. Long lasting and new promising concepts such as transcatheter aortic valve implantation are promoting the use of bioprosthesis even in younger patients. However, it is up to the individual patient to decide.

National trends in utilization and in-hospital outcomes of mechanical versus bioprosthetic aortic valve replacements

OBJECTIVE

Substantial controversy surrounds the choice between a mechanical versus bioprosthetic prosthesis for aortic valve replacement (AVR), based on age. This study aims to investigate national trends and in-hospital outcomes of the 2 prosthesis choices.

METHODS

All patients aged >18 years in the National Inpatient Sample who received an AVR between 1998 and 2011 were considered. Valve-type use was examined by patient, procedural, and hospital characteristics, after which we matched patients based on their propensity score for receiving a bioprosthetic valve and compared their in-hospital outcomes.

RESULTS

Bioprosthetic valves comprised 53.3% of 767,375 implanted valves, an increase in use from 37.7% in the period 1998 to 2001 to 63.6% in the period 2007 to 2011. The median age was 74 years for patients receiving bioprosthetic valves, and 67 years for those receiving mechanical valves. Use of bioprosthetic valves increased across all age groups, most markedly in patients age 55 to 64 years. Compared with patients receiving mechanical valves, these patients had a higher incidence of renal disease (8.0% vs 4.2%), coronary artery disease (58.5% vs 50.5%), concomitant coronary artery bypass grafting (46.7% vs 41.9%), and having surgery in a high-volume (>250 cases per year) center (31.3% vs 18.5%). Patients receiving bioprosthetic valves had a higher occurrence of in-hospital complications (55.9% vs 48.6%), but lower in-hospital mortality (4.4% vs 4.9%) than patients receiving mechanical valves. This difference was confirmed in propensity-matched analyses (complications: 52.7% vs 51.5%; mortality: 4.3% vs 5.2%).

CONCLUSIONS

Use of bioprosthetic valves in AVR increased dramatically from 1998 to 2011, particularly in patients age 55 to 64 years. Prosthesis selection varied significantly by facility, with low-volume facilities favoring mechanical valves. Aortic valve replacement with a bioprosthetic valve, compared with a mechanical valve, was associated with lower in-hospital mortality.

Cost-Effectiveness of the Combined Use of Warfarin and Low-Dose Aspirin versus Warfarin Alone in Egyptian Patients with Aortic Valve Replacements: A Markov Model

BACKGROUND

The combination of antiplatelet and anticoagulant therapy significantly reduces the rate of thromboembolic events in patients with heart valves compared with anticoagulant therapy alone. Cost-effectiveness of this therapy in Egypt, however, has not yet been established.

OBJECTIVE

The aim of the present study was to evaluate the cost-effectiveness of the combined use of warfarin and low-dose aspirin (100 mg) versus warfarin alone in patients with mechanical aortic heart valve prostheses who began therapy at the age of 50 to 60 years over a 5-year period from the perspective of the medical providers.

METHODS

A cohort Markov process model with five health states (recovery, reoperation, bleeding, thromboembolism, and death) based on Egyptian clinical practice was derived from published sources. The clinical parameters were derived from meta-analyses of randomized controlled trials of patients with mechanical valve prostheses. The quality of life of the health states was derived using the available published data. Direct medical costs were obtained from four top-rated governmental cardiology hospitals in Egypt. All costs and effects were discounted at 3.5% annually. All costs were converted using the purchasing power parity rate and are reported in US $ for the financial year of 2013.

RESULTS

The total quality-adjusted life-years (QALYs) were estimated to be 1.1616 and 1.1199 for the warfarin plus aspirin group and the warfarin group, respectively, which resulted in a difference of 0.0416 QALYs. The total costs for the warfarin plus aspirin group and the warfarin group were US $307.33 and US $315.25, respectively (the difference was US $7.92), which yielded an incremental cost-effectiveness ratio of -190.38 for the warfarin plus aspirin group. Thus, the combined therapy was dominant. Various one-way sensitivity analyses indicated that probabilities of reoperation and bleeding in the recovery state had the greatest effects on incremental costs. The model parameters that had the greatest effects on incremental QALYs were the relative risk reduction of death and the utility value in the recovery state.

CONCLUSIONS

The present study is the first cost-utility analysis to conclude that, from the perspective of Egyptian medical providers, combined therapy is more effective and less costly than warfarin alone for patients with mechanical aortic valve prostheses. For clinicians and patients who choose to focus on minimizing thromboembolic risk, these results suggest that combined therapy offers the best protection. This study helps to inform decisions about the allocation of health care system resources and to achieve better health in the Egyptian population.

Long-term safety and effectiveness of mechanical versus biologic aortic valve prostheses in older patients: results from the Society of Thoracic Surgeons Adult Cardiac Surgery National Database

BACKGROUND

There is a paucity of long-term data comparing biological versus mechanical aortic valve prostheses in older individuals.

METHODS AND RESULTS

We performed follow-up of patients aged 65 to 80 years undergoing aortic valve replacement with a biological (n=24 410) or mechanical (n=14 789) prosthesis from 1991 to 1999 at 605 centers within the Society of Thoracic Surgeons Adult Cardiac Surgery Database using Medicare inpatient claims (mean, 12.6 years; maximum, 17 years; minimum, 8 years), and outcomes were compared by propensity methods. Among Medicare-linked patients undergoing aortic valve replacement (mean age, 73 years), both reoperation (4.0%) and endocarditis (1.9%) were uncommon to 12 years; however, the risk for other adverse outcomes was high, including death (66.5%), stroke (14.1%), and bleeding (17.9%). Compared with those receiving a mechanical valve, patients given a bioprosthesis had a similar adjusted risk for death (hazard ratio, 1.04; 95% confidence interval, 1.01-1.07), higher risks for reoperation (hazard ratio, 2.55; 95% confidence interval, 2.14-3.03) and endocarditis (hazard ratio, 1.60; 95% confidence interval, 1.31-1.94), and lower risks for stroke (hazard ratio, 0.87; 95% confidence interval, 0.82-0.93) and bleeding (hazard ratio, 0.66; 95% confidence interval, 0.62-0.70). Although these results were generally consistent among patient subgroups, bioprosthesis patients aged 65 to 69 years had a substantially elevated 12-year absolute risk of reoperation (10.5%).

CONCLUSIONS

Among patients undergoing aortic valve replacement, long-term mortality rates were similar for those who received bioprosthetic versus mechanical valves. Bioprostheses were associated with a higher long-term risk of reoperation and endocarditis but a lower risk of stroke and hemorrhage. These risks varied as a function of a patient's age and comorbidities.

Aortic Valve Replacement in the Elderly

Background—

Few data exist on long-term outcomes of elderly patients after aortic valve replacement. We evaluated latest follow-up information for patients ≥70 years of age after aortic valve replacement.

Methods and Results—

Late overall survival of 2890 consecutive patients ≥70 years of age who underwent aortic valve replacement between January 1993 and December 2007 was reviewed retrospectively, analyzed, and stratified by preoperative and intraoperative variables. Observed 5-, 10-, and 15-year late postoperative survival was lower than generally expected (68%, 34%, and 8% versus 70%, 42%, and 20%, respectively; P <0.001). Independent predictors of late death included older age, renal failure, diabetes mellitus, stroke, myocardial infarction, immunosuppression, prior coronary artery bypass grafting, implanted pacemaker, lower ejection fraction, hypertension, and New York Heart Association class III or IV. After stratification by age–comorbidity risk score, 10-year survival for the lowest-risk group (n=946 [33%]) was similar to expected survival (55% versus 55%; P =0.50), but for the highest-risk group (n=564 [20%]), survival was significantly lower than expected (9% versus 26%; P <0.001). For 229 pairs of propensity-matched patients with mechanical or biological prostheses, survival was not significantly different (67%, 40%, and 19% versus 71%, 45%, and 7% at 5, 10, and 15 years, respectively; P =0.81). Structural deterioration of bioprostheses occurred in 64 patients (2.4%).

Conclusions—

Survival of elderly patients after aortic valve replacement is influenced by age and preoperative comorbidities; 33% at lowest risk had overall survival similar to that of an age- and sex-matched general population. There was no sufficient evidence that valve type affected survival. Structural deterioration of aortic bioprostheses was rare.

Cardiac crossroads: deciding between mechanical or bioprosthetic heart valve replacement

Nearly 15 million people in the United States suffer from either aortic or mitral valvular disease. For patients with severe and symptomatic valvular heart disease, valve replacement surgery improves morbidity and mortality outcomes. In 2009, 90,000 valve replacement surgeries were performed in the United States. This review evaluates the advantages and disadvantages of mechanical and bioprosthetic prosthetic heart valves as well as the factors for consideration in deciding the appropriate valve type for an individual patient. Although many caveats exist, the general recommendation is for patients younger than 60 to 65 years to receive mechanical valves due to the valve's longer durability and for patients older than 60 to 65 years to receive a bioprosthetic valve to avoid complications with anticoagulants. Situations that warrant special consideration include patient co-morbidities, the need for anticoagulation, and the potential for pregnancy. Once these characteristics have been considered, patients' values, anxieties, and expectations for their lifestyle and quality of life should be incorporated into final valve selection. Decision aids can be useful in integrating preferences in the valve decision. Finally, future directions in valve technology, anticoagulation, and medical decision-making are discussed.

Choice of prosthetic heart valve in adults an update

In the last 7 years, more data have reconfirmed that patients' comorbid conditions are very important factors determining patient outcomes. Prosthetic heart valves (PHVs) that require aortic root replacement in the absence of aortic root disease are associated with poorer outcomes. For the vast majority of patients, the choice of PHV is between a mechanical valve and a stented bioprosthesis. The choice is largely dependent upon the age of the patient at the time of PHV implantation and on which complication the patient wants to avoid: specifically, anticoagulation therapy and its complications with the mechanical valve, and structural valve deterioration with a bioprosthesis. Data on the pros and cons of the choices and exceptions to the rules are discussed, and a new algorithm is developed.

The right choice of prosthesis for patients undergoing aortic valve surgery: searching the truth

Aortic valve surgery is suggested when native aortic valve is diseased and complications outweigh the risks. Choice of prosthesis for aortic valve surgery is vastly undetermined, in part due to the varied options (bioprosthetic, mechanical prosthesis, homografts and allografts) available. The technical issues during valve surgery and the anticoagulation concerns along with the patient type with respect to age, ethnicity, sex and quality of life do contribute to the challenge for deciding the type of valve prosthesis best substituted to the diseased native valve. Here we attempt to unravel the controversies and present a holistic approach towards settling on the best possible prosthesis for a diseased aortic valve.

Usefulness of microsimulation to translate valve performance into patient outcome: Patient prognosis after aortic valve replacement with the Carpentier–Edwards supra-annular valve

OBJECTIVE

Numerous reports have been published documenting the results of aortic valve replacement. It is often not easy to translate these outcomes involving the condition of the valve into the actual consequences for the patient. We previously developed an alternative method to study outcome after aortic valve replacement that allows direct estimation of patient outcome after aortic valve replacement: microsimulation modeling. The goal of this article is to provide insight into microsimulation methodology and to give an overview of the advantages and disadvantages of simulation methods (in particular microsimulation) in comparison with standard methods of outcome analysis.

METHODS

By using a primary dataset containing 1847 patients and 14,429 patient-years, advantages and disadvantages of standard methods of outcome analysis are discussed, and the potential role of microsimulation is illustrated by means of a step-by-step explanation of building, testing, and using such a model.

RESULTS

Total life expectancy, event-free life expectancy, and reoperation-free life expectancy for a 65-year-old male patient were 10.6 years, 9.2 years, and 9.8 years, respectively. Lifetime risk of reoperation due to structural valve deterioration was 13.3%.

CONCLUSIONS

Microsimulation is capable of providing accurate estimates of age-related life expectancy and lifetime risk of reoperation for patients who underwent aortic valve replacement with the Carpentier-Edwards supra-annular valve. It provides a useful tool to facilitate and optimize the choice for a specific heart valve prosthesis in a particular patient.

Actual and actuarial probabilities of competing risks: apples and lemons

The probability of a type of failure that is not inevitable, but can be precluded by other events such as death, is given by the cumulative incidence function. In cardiac research articles, it has become known as the actual probability, in contrast to the actuarial methods of estimation, usually implemented by the Kaplan-Meier (KM) estimate. Unlike cumulative incidence, KM attempts to predict what the latent failure probability would be if death were eliminated. To do this, the KM method assumes that the risk of dying and the risk of failure are independent. But this assumption is not true for many cardiac applications in which the risks of failure and death are negatively correlated (ie, patients with a higher risk of dying have a lower risk of failure, and patients with a lower risk of death have a higher risk of failure, which is a condition called informative censoring). Recent editorials in two cardiac journals have promoted the use of the KM method (actuarial estimate) for competing risk events (specifically for heart valve performance) and criticized the use of the cumulative incidence (actual) estimates. This report has two aims: to explain the difference between these two estimates and to show why the KM is generally not appropriate. In the process we will rely on alternative representations of the KM estimator (using redistribution to the right and inverse probability weighting) to explain the difference between the two estimates and to show how it may be possible to adjust KM to overcome the informative censoring.

Risk-corrected impact of mechanical versus bioprosthetic valves on long-term mortality after aortic valve replacement

OBJECTIVE

Choice of a mechanical or biologic valve in aortic valve replacement remains controversial and rotates around different complications with different time-related incidence rates. Because serious complications will always "spill over" into mortality, our aim was to perform a meta-analysis on overall mortality after aortic valve replacement from series with a maximum follow-up of at least 10 years to determine the age- and risk factor-corrected impact of currently available mechanical versus stented bioprosthetic valves.

METHODS

Following a formal study protocol, we performed a dedicated literature search of publications during 1989 to 2004 and included articles on adult aortic valve replacement with a mechanical or stented bioprosthetic valve if age, mortality statistics, and prevalences of well-known risk factors could be extracted. We used standard and robust regression analyses of the case series data with valve type as a fixed variable.

RESULTS

We could include 32 articles with 15 mechanical and 23 biologic valve series totaling 17,439 patients and 101,819 patient-years. The mechanical and biologic valve series differed in regard to mean age (58 vs 69 years), mean follow-up (6.4 vs 5.3 years), coronary artery bypass grafting (16% vs 34%), endocarditis (7% vs 2%), and overall death rate (3.99 vs 6.33 %/patient-year). Mean age of the valve series was directly related to death rate with no interaction with valve type. Death rate corrected for age, New York Heart Association classes III and IV, aortic regurgitation, and coronary artery bypass grafting left valve type with no effect. Included articles that abided by current guidelines and compared a mechanical and biologic valve found no differences in rates of thromboembolism.

CONCLUSION

There was no difference in risk factor-corrected overall death rate between mechanical or bioprosthetic aortic valves irrespective of age. Choice of prosthetic valve should therefore not be rigorously based on age alone. Risk of bioprosthetic valve degeneration in young and middle-aged patients and in the elderly and old with a long life expectancy would be an important factor because risk of stroke may primarily be related to patient factors.

Treatment variation in older black and white patients undergoing aortic valve replacement

BACKGROUND

Most prior studies of racial differences in the delivery of cardiac care have focused on potential differences in treatment by individual physicians and hospitals. However, differential use of hospitals with variable practice patterns might also contribute to variations in care.

METHODS AND RESULTS

We compared the use of bioprosthetic valves (BPVs) in 78,154 black and white Medicare beneficiaries > or =65 years of age undergoing aortic valve replacement in 904 US hospitals during 1999 through 2001. Generalized linear mixed models were used to account first for differences in patient characteristics and then for differences in hospitals used by black and white patients. BPV use was lower in black patients relative to white patients after adjustment for patient characteristics (relative risk, 0.93; 95% CI, 0.91 to 0.95; P<0.001). However, black patients were more likely to undergo surgery in hospitals in the lowest quintile of BPV use overall (29% versus 20% of white patients; P<0.001). After hospital-level variability in BPV use was accounted for, the use of BPVs was actually somewhat higher in black patients (relative risk, 1.06; 95% CI, 1.04 to 1.09; P<0.001). Model discrimination as measured by the c statistic was markedly higher after the addition of hospital effects (0.80 versus 0.59 for patient characteristics alone; P<0.001).

CONCLUSIONS

Accounting for differences in hospitals preferentially used by black and white patients had a major impact on estimating racial differences in the use of BPVs in patients undergoing aortic valve replacement. Hospital-level effects explained a larger proportion of the variation in BPV use than race and other patient characteristics alone.

Prognosis After Aortic Valve Replacement With the Carpentier-Edwards Pericardial Valve: Use of Microsimulation

BACKGROUND

The second-generation Carpentier-Edwards pericardial valve (Edwards Lifesciences LLC, Irvine, CA) is widely used for aortic valve replacement. However, knowledge on the long-term outcomes of patients after valve implantation is incomplete. We used microsimulation to calculate the long-term outcome of any given patient after aortic valve replacement with the Carpentier-Edwards pericardial valve.

METHODS

A meta-analysis of 8 reports on aortic valve replacement with the Carpentier-Edwards pericardial valve (2,685 patients; 12,250 patient years) was used to estimate the hazards of valve-related events other than structural valvular deterioration. Structural valvular deterioration was described by age-dependent Weibull curves calculated from 18-year follow-up, premarket approval, Carpentier-Edwards pericardial primary data. These estimates provided the input data for the parameters of the microsimulation model, which was then used to calculate the outcomes of patients of different ages after valve implantation. The model estimates of survival were validated using two external data sets.

RESULTS

The Weibull analysis estimated a median time to reoperation for structural valvular deterioration ranging from 18.1 years for a 55-year-old male to 23.2 years for a 75-year-old male. For a 65-year-old male, microsimulation calculated a life expectancy and event-free life expectancy of 10.8 and 9.1 years, respectively. The lifetime risk of at least one valve-related event was 38% and that of reoperation due to structural valvular deterioration 17%, respectively, for this patient. The model estimates of survival showed good agreement with external data.

CONCLUSIONS

Microsimulation provides detailed insight into the long-term prognosis of patients after aortic valve replacement. The Carpentier-Edwards pericardial valve performs satisfactorily and offers a low lifetime risk of reoperation due to structural valvular deterioration, especially for elderly patients requiring aortic valve replacement.

Hospital Volume and Selection of Valve Type in Older Patients Undergoing Aortic Valve Replacement Surgery in the United States

Background— Hospital volume has been linked to quality of care. The relation between hospital volume and recommended use of bioprosthetic valves in older patients undergoing aortic valve replacement (AVR) is unknown.

Methods and Results— We identified 80 470 patients aged ≥65 years undergoing isolated AVR (with or without bypass surgery) in 1045 US hospitals during 1999–2001 from Medicare Part A files. International Classification of Diseases, Ninth Revision, Clinical Modification codes were used to identify patients undergoing bioprosthetic valve (35.21) or mechanical valve (35.22) AVR. The sample was categorized into deciles on the basis of the valve surgery volume of the hospital. Generalized estimating equations determined the relative risk of receiving a bioprosthetic valve in different volume deciles, with adjustment for age, gender, race, comorbidity, and other factors. Bioprosthetic valve use increased ( P <0.001) from 44% in 1999 to 52% in 2001 and with age (from 36% in patients aged 65 to 69 years to 60% in patients aged ≥90 years). Rates were directly related ( P <0.001) to volume, rising from 28% in the 1st decile to 68% in the 10th decile. With the use of generalized estimating equations, the relative risk of bioprosthetic valve use, relative to the 1st decile, progressively increased from 1.2 (95% CI, 1.1 to 1.4) in the 2nd decile to 2.3 (95% CI, 1.9 to 2.7) in the 10th decile.

Conclusions— Hospital volume was a strong predictor of bioprosthetic valve use in older patients undergoing AVR. The lower use of bioprosthetic valves in low-volume hospitals is at odds with recent guidelines recommending bioprosthetic valves in patients aged ≥65 years. These findings further support the use of volume as a marker of hospital quality.

Comparison of outcomes after aortic valve replacement with a mechanical valve or a bioprosthesis using microsimulation

BACKGROUND

Mechanical valves and bioprostheses are widely used for aortic valve replacement. Though previous randomised studies indicate that there is no important difference in outcome after implantation with either type of valve, knowledge of outcomes after aortic valve replacement is incomplete.

OBJECTIVE

To predict age and sex specific outcomes of patients after aortic valve replacement with bileaflet mechanical valves and stented porcine bioprostheses, and to provide evidence based support for the choice of prosthesis.

METHODS

Meta-analysis of published results of primary aortic valve replacement with bileaflet mechanical prostheses (nine reports, 4274 patients, and 25,726 patient-years) and stented porcine bioprostheses (13 reports, 9007 patients, and 54,151 patient-years) was used to estimate the annual risks of postoperative valve related events and their outcomes. These estimates were entered into a microsimulation model, which was employed to calculate age and sex specific outcomes after aortic valve replacement.

RESULTS

Life expectancy (LE) and event-free life expectancy (EFLE) for a 65 year old man after implantation with a mechanical valve or a bioprosthesis were 10.4 and 10.7 years and 7.7 and 8.4 years, respectively. The lifetime risk of at least one valve related event for a mechanical valve was 48%, and for a bioprosthesis, 44%. For LE and EFLE, the age crossover point between the two valve types was 59 and 60 years, respectively.

CONCLUSIONS

Meta-analysis based microsimulation provides insight into the long term outcome after aortic valve replacement and suggests that the currently recommended age threshold for implanting a bioprosthesis could be lowered further.

Should coronary artery bypass graft surgery patients with mild or moderate aortic stenosis undergo concomitant aortic valve replacement?

OBJECTIVES

This study utilizes Markov decision analysis to assess the relative benefits of prophylactic aortic valve replacement (AVR) at the time of coronary artery bypass graft surgery (CABG). Multiple sensitivity analyses were also performed to determine the variables that most profoundly affect outcome.

BACKGROUND

The decision to perform CABG or concomitant CABG and AVR (CABG/AVR) in asymptomatic patients who need CABG surgery but have mild to moderate aortic stenosis (AS) is not clear-cut.

METHODS

We performed Markov decision analysis comparing long-term, quality-adjusted life outcomes of patients with mild to moderate AS undergoing CABG versus CABG/AVR. Age-specific morbidity and mortality risks with CABG, CABG/AVR, and AVR after a prior CABG were based on the Society of Thoracic Surgeons national database (n = 1,344,100). Probabilities of progression to symptomatic AS, valve-related morbidity, and age-adjusted mortality rates were obtained from available published reports.

RESULTS

For average AS progression, the decision to replace the aortic valve at the time of elective CABG should be based on patient age and severity of AS measured by echocardiography. For patients under age 70 years, an AVR for mild AS is preferred if the peak valve gradient is >25 to 30 mm Hg. For older patients, the threshold increases by 1 to 2 mm Hg/year, so that an 85-year-old patient undergoing CABG should have AVR only if the gradient exceeds 50 mm Hg. The AS progression rate also influences outcomes. With slow progression (<3 mm Hg/year), CABG is favored for all patients with AS gradients <50 mm Hg; with rapid progression (>10 mm Hg/year), CABG/AVR is favored except for patients >80 years old with a valve gradient <25 mm Hg.

CONCLUSIONS

This study provides a decision aid for treating patients with mild to moderate AS requiring CABG surgery. Predictors of AS progression in individual patients need to be better defined.

Prognosis after aortic root replacement with cryopreserved allografts in adults

BACKGROUND

Aortic root replacement with cryopreserved allografts is associated with excellent hemodynamics, little endocarditis, low thromboembolic event rates, and no need for anticoagulation. There is, however, concern regarding the long-term durability of this valve substitute, especially in younger patients. Meta-analysis and microsimulation were used to calculate age-specific long-term prognosis after allograft aortic root replacement based on current evidence.

METHODS

Our center's experience with cryopreserved allograft aortic root replacement in 165 adult patients was combined in a meta-analysis with reported and individual results from four other hospitals. Using this information, the microsimulation model predicted age- and gender-specific total and reoperation-free and event-free life expectancy.

RESULTS

The pooled results comprised 629 patients with a total follow-up of 1860 patient-years (range 0 to 12.8 years). Annual risks were 0.6% for thromboembolism, 0.05% for bleeding, 0.5% for endocarditis, and 0.5% for nonstructural valve failure. Structural allograft failure requiring reoperation occurred in 15 patients, and a patient age-specific Weibull function was constructed accordingly. Calculated total life expectancy varied from 27 years in a 25-year-old to 12 years in a 65-year-old male; corresponding actual lifetime risk of reoperation was 89% and 35%, respectively.

CONCLUSIONS

Cryopreserved aortic allografts have an age-related limited durability. This results in a considerable lifetime risk of reoperation, especially in young patients. The combination of meta-analysis and microsimulation provides an appropriate tool for estimating individualized long-term outcome after aortic valve replacement and can be useful both for patient counseling and prognostic research purposes.

Valved stentless composite graft: clinical outcomes and hemodynamic characteristics

BACKGROUND

The valved stentless composite graft has become well established in our hospital for replacement of the ascending aorta and aortic valve in elderly patients and those with contraindication for lifelong anticoagulation. This study was conducted to evaluate the postoperative hemodynamic characteristics and clinical outcomes after implantation of this device.

METHODS

Between November 1998 and February 2001, 45 consecutive patients with a mean age of 69 years underwent implantation of a composite graft using a stentless valve prosthesis (Toronto SPV) incorporated in a collagen-coated Dacron tube (InterGard). The indication for surgery was aortic valve disease with an accompanying true aneurysm of the ascending aorta in 42 patients and a dissection of the aortic wall in 3 patients. Postoperative echocardiographic examinations were performed before discharge from the hospital and at the time of the follow-up. Mean follow-up duration was 18 months (range 3 to 30 months).

RESULTS

There was no perioperative mortality. During follow-up, there were two noncardiac, nonvalve-related deaths. Echocardiographic evaluation before discharge and at follow-up demonstrated favorable hemodynamics of the valve prosthesis with mean transvalvular gradients of 8.5 +/- 2.9 mmHg and 8.0 +/- 3.1 mmHg, respectively. No regurgitation across the valve and no contact of the cusps with the Dacron tube were seen in any case.

CONCLUSIONS

A stentless composite graft for replacement of the aortic valve and ascending aorta offers excellent hemodynamic results and is a suitable device for patients in whom anticoagulation should be avoided.

Better anticoagulation control improves survival after valve replacement

OBJECTIVE

We sought to assess the effect of anticoagulation control on long-term survival after valve replacement with the Medtronic Hall valve (Medtronic, Inc, Minneapolis, Minn).

METHODS

Prospective follow-up data, including 82,297 international normalized ratios, were collected for 1476 patients undergoing single valve replacement with the Medtronic Hall valve between 1979 and 1994, with follow-up to the end of 1998. After excluding 204 patients who either died within 30 days or had fewer than 10 international normalized ratios recorded beyond 30 days, there were 10,203 patient years of follow-up for analysis. Anticoagulation variability was measured as the percentage of international normalized ratios outside a target range of 2.0 to 4.0 for each patient.

RESULTS

Linearized rates for late death rose progressively with increasing deciles of anticoagulation variability for both aortic and mitral valve replacement (2.7% and 3.3% per year, respectively, in deciles 1 and 2 up to 9.5% and 14.6% per year, respectively, in deciles 6-10; P <.001). Survival at 15 years after aortic valve replacement was 59% for low anticoagulation variability (deciles 1 and 2), 55% for intermediate anticoagulation variability (decile 3), and 28% for high anticoagulation variability (deciles 4-10); survivals at 15 years after mitral valve replacement were 56%, 42%, and 24%, respectively (P <.001 between low-intermediate anticoagulation variability and high anticoagulation variability for both aortic and mitral valve replacement). On multivariate analysis, significant predictors of reduced survival were anticoagulation variability per 20% increase (hazard ratio, 1.8), diabetes (hazard ratio, 1.6), decade of age (hazard ratio, 1.6), concomitant coronary artery bypass grafting (hazard ratio, 1.5), male sex (hazard ratio, 1.4), hypertension (hazard ratio, 1.4), New York Heart Association class III or IV (hazard ratio, 1.3), and non-sinus rhythm (hazard ratio, 1.2). Patients with low anticoagulation variability who were in sinus rhythm and did not have diabetes, coronary bypass grafting, or hypertension had survivals equal to those of the age- and sex-matched general population at 15 years. The incidence of valve-related deaths was significantly higher with high anticoagulation variability compared with the incidence with low-intermediate anticoagulation variability for both aortic (1.4% vs 0.5% per year, P <.001) and mitral valve replacement (1.5% vs 0.5% per year, P <.001). By means of univariate analysis, high anticoagulation variability was significantly associated with New York Heart Association class III or IV at 5 years postoperatively (P <.001) and with age of greater than 60 years at the time of the operation (P =.002).

CONCLUSIONS

High anticoagulation variability is the most important independent predictor of reduced survival after valve replacement with a mechanical valve. Better anticoagulation control should improve survival.

The Carpentier-Edwards stented supra-annular pericardial aortic valve prosthesis: clinical durability and hemodynamic performance

There are encouraging reports of satisfactory long-term experiences with second-generation stent-mounted glutaraldehyde-fixed pericardial aortic valve prostheses. Durability has improved, but the issue has not been completely resolved. There is disagreement whether the small sizes of these prostheses are associated with inferior outcomes. Large-scale, long-term multivariable analyses of actual clinical results are needed to complement actuarial calculations of important end points from multiple small series to improve the ability to match individual patients with prostheses that suit their needs and preferences.

[Patient adapted valve selection: biological vs. mechanical heart valve replacement in aortic valve diseases]

Since the first aortic valve replacement performed by Harken in 1960, the operation of aortic valve disease by replacing the native valve with a heart valve prosthesis has become one of the most frequently performed procedures in cardiac surgery. For valve replacement there are biological (xenografts and homografts) and mechanical heart valve prostheses available. When choosing the most suitable prosthesis the limited durability of a biological prosthesis and the risks of lifelong anticoagulation for a mechanical prosthesis have to be balanced.In this article the indication for operation of aortic valve stenosis and aortic regurgitation are discussed first. Based on the literature of the last 2 years the advantages and disadvantages of mechanical and biological heart valve prostheses (xenograft, homograft and ROSS procedure) are discussed. In addition rarely used techniques like aortic valve reconstruction are presented.Due to the fact that a biological prosthesis has a durability of 12-15 years and the risk of bleeding complications under anticoagulation grows with increasing age, the choice of a biological prosthesis can be recommended from the age of 65 years. Results of long-term studies at to whether this limit can be diminished by using a stentless biological prosthesis have to be awaited.

Aortic valve replacement: current clinical practice and opportunities for quality improvement

This is a review of the current clinical practice and opportunities for quality improvement in aortic valve replacement surgery. The topics include trends and regional variation in procedure rates, and changes in the use of aortic valve replacement among the elderly. Recent developments guiding the choice of prosthetic valves and trends in in-hospital mortality rates for aortic valve surgery are summarized. Lastly, a discussion of topics relevant to clinical practice improvement including the implementation of clinical practice guidelines, the need for consensus on risk adjustment, better understanding of volume-outcome effects, and the opportunities for comprehensive assessment of aortic valve surgery.