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Aortic stenosis (AS) is now the most frequent heart valve disease in industrialised countries and its prevalence sharply increases with age.1 2 Thus, with the lengthening of life expectancy, the population of old patients with AS is expected to grow in the future.
Aortic valve replacement (AVR) remains the reference treatment for severe symptomatic AS and there are no explicit restrictions for intervention related to age itself according to guidelines.3 4 However, decision making for intervention is often difficult in old patients in whom it may not be obvious whether the benefit of surgery, as compared to spontaneous outcome, outweighs the risk of intervention.
The literature enables results of AVR to be better ascertained in the elderly and compared to the natural history of AS. In addition to their usefulness in improving decision making for surgery, surgical series are the reference for the evaluation of new techniques using transcatheter heart valve prosthesis. As regards current patient management, the difficulty is to translate data from the literature to an analysis of the risk/benefit ratio of different therapeutic possibilities tailored to the individual patient.
Natural history of aortic stenosis
The natural history of AS has been elucidated by the pioneering work of Ross and Braunwald in the 1960s. The onset of severe symptoms had a major impact since they were associated with a shortening of median survival to 5 years. Median survival was <2 years in the case of left heart failure and <1 year in the case of global heart failure. These findings remain the basis of the recommendation to operate on patients with severe symptomatic AS.3 4 However, the extrapolation of these findings to the elderly with AS may be debatable. In Ross and Braunwald’s study, death occurred at an average age of 63 years.
A contemporary series of elderly patients with severe AS showed that there was a wide range of survival rates in non-operated patients. The three predictive factors of poor spontaneous outcome were New York Heart Association (NYHA) class III or IV, associated mitral regurgitation, and left ventricular systolic dysfunction.5 The combination of these three factors identified a subgroup at particularly high risk, with a 3 year survival rate of only 20%. On the other hand, 3 year survival was over 80% in patients who did not have any of these three factors.
Impact of comorbidities on life expectancy
Comorbidities are frequent in the elderly with AS. This is obviously related to the increased frequency of comorbidities with age in the general population. The high frequency of comorbidities related to atherosclerosis is also explained by the fact that AS shares a number of common pathophysiological features and clinical risk factors with atherosclerosis.6
Multivariate scores enable the impact of comorbidities on life expectancy to be assessed. The Charlson comorbidity index combines 19 comorbid conditions which are weighed according to their prognostic impact. More recently, a multivariate scoring system has been specifically developed and validated in the elderly. It includes comorbidities and measures of functional capacity and has been shown to have a good predictive accuracy in the estimation of 4 year mortality in different age categories (table 1, fig 1).7
RESULTS OF SURGERY
A number of contemporary series have reported the results of AVR in the elderly. Most series published in the last 10 years have reported operative mortality rates around 10% in the octogenarian (table 2). Like operative mortality, operative morbidity is higher than in younger patients, in particular as regards the frequency of stroke (between 5–10% in most series). Postoperative stroke is more frequent in patients who had associated coronary artery bypass grafting, which illustrates the impact of associated atherosclerosis.
Beyond the estimation of mean operative mortality, risk assessment should be adapted to patient characteristics. Large series led to consistent results demonstrating a strong link between operative mortality and the following predictive factors:
Advanced stage of heart disease, whether attested by heart failure, NYHA class IV, decreased left ventricular ejection fraction, or atrial fibrillation
Comorbidities, in particular chronic obstructive pulmonary disease, renal insufficiency, or associated atherosclerosis of coronary or peripheral arteries
Need for urgent surgery.
Associated atherosclerosis plays an important role given its frequency and implications. Significant coronary artery disease is present in approximately half of patients with AS after the age of 75 years.8 It requires coronary artery bypass grafting to be associated with AVR which increases operative mortality in most series. The likely explanations of this are the increased complexity and duration of intervention and also the fact that patients with coronary artery disease frequently have other locations of atherosclerotic disease which may cause complications. In particular, patients with coronary artery disease have a higher frequency of postoperative stroke which has an important impact on operative mortality.
The next step to individualise risk assessment is to combine the predictive factors to estimate the operative risk for any given patient. In a series of 675 patients undergoing AVR after the age of 75 years with a mean operative mortality of 12.4%, the predicted operative risk ranged from 5% for elective surgery in patients with few symptoms and normal and left ventricular function to more than 40% in those who underwent urgent surgery in NYHA class IV and had severe left ventricular dysfunction.9 Although it did not include comorbidities, the strength of this study was to draw attention to the considerable heterogeneity of operative risk in the elderly.
Individual risk assessment should also take into account certain patient characteristics which increase operative risk but are generally not identified as predictive factors given their rare occurrence—for example, porcelain aorta (fig 2) or prior radiation therapy.
Individual risk stratification using scores
Multivariate scores have been developed and validated to estimate operative mortality in cardiac surgery according to cardiac and non-cardiac patient characteristics. Ideally, they should offer a compromise between a wide applicability and a good discrimination.
The Euroscore has been evaluated in general cardiac surgery; however, it has been proven to have a good discriminant power in patients with heart valve disease.10 11 Its strengths are to have been widely validated and to be user-friendly. Other scores have been specifically developed for heart valve diseases, which would theoretically ensure better discrimination.12–14 In practice, different scores seem to have relatively close predictive abilities when tested in large populations of patients with heart valve disease (table 3).
However, scores have limitations when dealing with heart valve diseases in the elderly. Discrepancies between predicted and observed operative mortality have been described in patients with AS and are more pronounced in high risk patients.15 16 The reduced predictive ability of multivariate scores in high risk patients is probably related to the fact that high risk groups accounted only for a small proportion of the populations from which scores were elaborated. In addition, high risk patients form a particularly heterogeneous group, in which it is difficult to estimate accurately the individual contribution of each factor to operative mortality.
Late results of aortic valve surgery
After the postoperative period, late results of AVR are good in the elderly. Five year survival rates are estimated at between 50–70% after AVR in the octogenarian. Of course, survival rates are lower than in younger patients, but they favourably compare with life expectancy in a general population of the same age. Related survival—that is, compared to the expected survival—is particularly good in the elderly.17
As with operative mortality, late mortality after AVR is related to the evolution of heart disease before surgery (heart failure) and comorbidities.
Surgery also gives good results as regards quality of life. Elderly derive at least the same benefits as younger patients as regards physical activity, depression, and global indices of quality of life. The wide use of bioprostheses in this age range contributes to the absence of constraints directly related to valve surgery.
The number of patient characteristics which have an impact on the results of surgery as well as on spontaneous outcome underline the need for a thorough patient evaluation.
It is necessary to spend time on the analysis of case history. Symptom onset, which is the main factor leading to consider surgery, is often difficult to determine in the elderly since patients may have reduced their activity by themselves or because of associated diseases. Fatigue, rather than dyspnoea, can be the sign of limited effort tolerance. Case history also enables comorbidities, lifestyle, and patient’s wishes to be assessed.
Cardiac auscultation should pay attention to the abolition of the second heart sound, which is specific to severe AS and is particularly helpful when the murmur is of low intensity.
Echocardiographic examination is the cornerstone to confirm the diagnosis of AS, and assess its severity and its consequences on the left ventricle. It is of utmost importance to check for the consistency of different findings between themselves and with clinical assessment. Valve area below 0.6 cm2/m2 of body surface area is a marker of severe AS and it has the advantage of taking into account body size. Despite its flow dependence, aortic gradient should also be taken into account since it is less subject to errors of measurements. A mean aortic gradient over 40–50 mm Hg indicates severe stenosis.3 4
Coronary angiography is indicated before surgery and is also an important component of decision making, given the implications of coronary disease on operative risk and prognosis. Non-invasive assessment using computed tomography may emerge as a valid method for the comprehensive evaluation of coronary anatomy as well as valve area and left ventricular function. However, the predictive value of computed tomography for coronary disease remains suboptimal in this population where the prevalence of coronary disease and coronary calcification is high. Cardiac catheterisation is seldom needed to assess valve disease. It should be performed only in the rare cases where non-invasive assessment is inconclusive, and should not be systematically associated with coronary angiography.
Other investigations are indicated according to clinical evaluation, in particular as regards comorbidities.
Therapeutic decisions should be based on a risk–benefit analysis weighing the operative risk against the benefit of surgery as compared to the spontaneous outcome of AS. This decision should also take into account the patient’s life expectancy and quality of life regardless of AS. This analysis is particularly difficult in the elderly with AS given the heterogeneity of operative risk and spontaneous prognosis.
Despite their limitations, in particular in high risk patients, the interest of multivariate scoring systems is to combine a number of patient characteristics to reduce the subjectivity of the assessment of operative risk and life expectancy. Of course, they only represent an aid for decision making and should be integrated with many other factors in clinical judgement.
The benefit of surgery on late outcome should be interpreted in the light of life expectancy, which may be more compromised by age itself than by AS. For example, life expectancy in France at the age of 85 is 5 years for a man and 6 years for a woman, which is close to life expectancy after symptom onset in AS. Unlike in young patients, the main purpose of surgery in the elderly is to improve symptoms rather than to increase the duration of life. This explains why surgery is generally not considered in asymptomatic AS in the elderly since the operative risk is not justified by the spontaneous outcome.
Besides their negative impact on operative mortality and life expectancy, certain comorbidities, such as respiratory insufficiency or neurological dysfunction, compromise the improvement of quality of life following cardiac surgery.
Improvements in the knowledge of the different elements of decision making underline the importance of clinical judgement, which should take into account not only many patient characteristics but also their wishes and expectations. The final decision to operate or not should be taken according to a joint approach involving the cardiac surgeon, anaesthetist, cardiologist, and geriatrician if needed. This evaluation should lead to thorough assessment of the patient’s wishes as well as information of the patient and relatives.
Difficulties in decision making in the elderly with AS are not only related to the decision to operate or not, but also to the timing of surgery. Given the operative risk and the frequent reluctance of patients, it is seldom decided to consider surgery at the very beginning of symptoms. Symptoms are often difficult to interpret in the elderly and this tends also to defer the time at which surgery will be considered. Of all factors increasing operative mortality, the severity of symptoms is the only one on which clinicians can act by avoiding too late a decision for surgery. Therefore, it is of importance to weigh its risk and benefits at the onset of symptoms. This helps to avoid taking the decision in a patient with an advanced disease in an urgent situation, which increases operative mortality.
Modalities of intervention
A bioprosthesis is the substitute of choice in the elderly. Elderly women with AS frequently have a small aortic annulus size, which may favour patient–prosthesis mismatch. However, this does not seem to have a major impact in the elderly, unlike in patients with left ventricular dysfunction. Coronary artery bypass grafting should be combined in case of significant coronary disease. However, surgery should not be denied when severe symptomatic AS is associated with non-bypassable coronary disease.8 A hybrid approach combining preoperative coronary angioplasty and isolated AVR is feasible. However, this approach raises particular problems regarding the management of antiplatelet drugs after stenting and its results have not been evaluated in large series.
Management of the elderly patient with aortic stenosis: key points
Operative mortality of aortic valve replacement for aortic stenosis is approximately 10% in patients aged over 80 years. However, it is subject to important differences according to patient characteristics.
Symptom assessment is frequently difficult in the elderly and should take into account comorbidities and lifestyle.
The assessment of the severity and consequences of aortic stenosis relies mainly on echocardiography. It is necessary to check the consistency of different echocardiographic findings between themselves and with clinical assessment.
Old age in itself is not a valid reason to deny aortic valve replacement.
The decision to operate or not relies on a team approach, allowing for an individual estimation of the risk/benefit ratio taking into account predicted operative mortality, life expectancy according to age, comorbidities and the severity of valve disease.
The use of multivariate scores is useful to reduce the subjectivity of the assessment of operative risk, although they lack predictive accuracy in high risk patients.
THERAPEUTIC ALTERNATIVES IN NON-OPERATED PATIENTS
Twenty years ago, balloon aortic valvuloplasty emerged as a promising alternative for the treatment of AS in high risk patients. However, despite frequent functional improvement, there was only a limited and transient improvement in valve function. More importantly, balloon aortic valvuloplasty did not improve survival as compared with natural history. Therefore, risk–benefit analysis does not support balloon aortic valvuloplasty as an alternative to surgery. This explains why guidelines restrict indications for balloon aortic valvuloplasty to situations in which it is used as a bridge for subsequent AVR.3 4
Percutaneous implantation of a transcatheter heart valve prosthesis now seems to offer the possibility of a durable improvement in valve function at a lower risk than AVR. For ethical reasons, the first cases were performed only in patients who had contraindications to surgery because of end stage heart disease and/or severe comorbidities. This accounted for high mid term mortality rates; however, it demonstrated the feasibility of this approach. Growing experience and ongoing trials in patients at high operative risk, but whose life expectancy is not compromised in the short term, will allow more accurate evaluation of the clinical benefit of the procedure.18
When the prosthesis cannot be delivered using an endovascular approach because of the peripheral artery status, it is possible to insert the prosthesis using a minimally invasive, transapical, surgical approach.19
Finally, in patients with AS who would not undergo any intervention, medical treatment should be adapted to symptoms. No medical treatment has been shown to improve the prognosis of AS. Retrospective studies suggested that statins may slow the progression of AS but this has not been confirmed by the only randomised trial published so far.
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WHAT HAPPENS IN CURRENT PRACTICE?
The Euro Heart Survey on valvular heart disease provided information on the contemporary characteristics and management of patients with AS.1 Even more than in the general population, AS was by far the most frequent heart valve disease in the elderly (fig 3).
Of the 216 patients aged ⩾75 years who had severe symptomatic aortic AS, 72 (32%) were denied surgery. The two patient characteristics associated with a decision not to operate as assessed by multivariate analysis were left ventricular dysfunction and older age. On the other hand, comorbidities combined in the Charlson comorbidity index were not significantly associated with the decision to operate or not.20
It can be understood that clinicians are reluctant to consider surgery in patients aged over 85 or in those with major left ventricular dysfunction (ejection fraction ⩽30%), who accounted for only a small proportion of the population, however. The strong relationship between surgical denial in patients aged between 80–85 years and those with left ventricular ejection fraction between 30–50% is not supported by risk–benefit analysis, in particular in the absence of comorbidities. These patients are likely to derive a particular benefit from surgery in terms of duration and quality of life as compared with spontaneous outcome. On the other hand, it is surprising that the Charlson comorbidity index was not significantly associated with the decision not to operate. Most comorbidities increase the operative risk and are also associated with a significant decrease in life expectancy and have, therefore, a negative impact on the risk/benefit ratio of AVR.
The difficulties in the management of AS in the elderly are greatly related to the heterogeneity of operative risk and spontaneous outcome. This is the consequence of the diversity of patient characteristics. Validated multivariate scores aiming to assess operative mortality and life expectancy represent an aid to decision making. Their use should be encouraged to improve current practices according to guidelines. This may avoid patients being denied surgery only because of age or left ventricular dysfunction, as well as allowing for a better consideration of the impact of comorbidities.
The availability of less invasive techniques, combined with lengthened lifespan, is likely to increase the referral of elderly with AS presenting with a high risk profile. This challenging perspective stresses the need for a thorough evaluation of new techniques and also a better knowledge of the natural history of AS in the elderly and its determinants. The predictive value of multivariate predictive scores should be improved to guide the individual choice between AVR, less invasive techniques, or abstention. It remains that the final therapeutic decision can rely only on clinical judgement based on a team approach. This is mandatory in order to individualise decision making according to the expected risks and benefits of the different treatments and the wishes of the informed patient.
A contemporary assessment of the presentation and actual practices in the management of patients with valvular heart disease in 25 European countries.
The first estimation of the prevalence of heart valve diseases in the general population, showing a sharp increase in the prevalence of aortic stenosis after the age of 65 years.
The two recent guidelines review the rationale for interventions in valvular heart disease. It is clearly stated that age in itself is not a contraindication to aortic valve replacement.
A contemporary series improving the knowledge of the natural history of severe aortic stenosis. It shows in particular the strong negative impact of severe symptoms and left ventricular dysfunction on survival of non-operated patients.
A multivariate score based on a self questionnaire estimating life expectancy in the elderly according to age and comorbidities.
This large series led to the first simulation of operative mortality following aortic valve replacement in the elderly, pointing out the variability of operative risk according to patient characteristics.
This paper describes a user-friendly multivariate score predicting operative mortality, which was specifically elaborated and validated in patients with valvular heart disease.
This analysis of relative survival illustrates the importance of comparing observed survival to the expected outcome in sex- and age-matched populations.
This European survey shows that a third of patients aged over 75 years with severe symptomatic aortic stenosis are denied surgery and that the factors associated with a decision not to operate are not in accordance with guidelines.
Competing interests: In compliance with EBAC/EACCME guidelines, all authors participating in Education in Heart have disclosed potential conflicts of interest that might cause a bias in the article. Professor Iung has received speakers’ fee from Edwards Lifesciences and Sanofi-Aventis.
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