Prof. Bernard Iung,
This joint session between the Working Groups on valvular heart disease and cardiovascular surgery proposed a patient-based approach of aortic stenosis in the elderly.
The evaluation of symptoms plays an important role in the evaluation of aortic stenosis. The appearance of symptoms has a strong negative prognostic impact on survival and symptom onset is thus considered as an indication for aortic valve replacement in guidelines. Symptoms contribute also to determine the operative mortality. However, it is acknowledged that symptom evaluation and interpretation is subjective. This contributes probably to the under-treatment of aortic stenosis, which has been shown in a number of surveys in Europe and the United States. The objective evaluation of exercise tolerance may be performed using exercise testing. Exercise testing has been shown to reveal dyspnoea in approximately a third of the patients with aortic stenosis who claim to be asymptomatic and this has a strong prognostic impact on event-free survival. Another pitfall is the interpretation of symptoms. Since aortic stenosis is frequently encountered in all patients with comorbidities, it may be difficult to establish a causal relationship between aortic stenosis and dyspnoea. This is particularly the consequence of the high frequency of chronic obstructive pulmonary disease in series of elderly patients with aortic stenosis. This association is even more frequent when considering patients who are at risk for aortic valve replacement. In the Partner B trial which included patients considered unsuitable for surgery, 47% of them had chronic obstructive pulmonary disease and 23% were oxygen-dependent. In the Source registry including 1038 patients, 24% of the death occurring between 30 days and one month were attributed to pulmonary causes. Besides a careful analysis of clinical history, the assessment of the severity of aortic stenosis and left ventricular function, BNP level may also be useful.
Frailty has been defined as “a syndrome of decreased reserve and resistance to stressors, resulting from multiple declines across multiple physiologic systems leading to vulnerability to adverse outcomes”. Its prevalence is estimated between 20 and 30% after the age of 75. Frailty has an impact on survival in the community and also on operative mortality and complications following cardiac surgery. Thus, the assessment of frailty plays an important role in the evaluation of the risk of cardiac surgery in the elderly, but it is generally performed according to a subjective approach ("eye-ball test"). Frailty was initially defined by the presence of at least three criteria among weakness, weight loss, exhaustion, low physical activity, and slowed walking speed. However, certain criteria may be difficult to evaluate in the elderly with valvular disease. The Columbia frailty index combines serum albumin level, a modified physical performance test, the assessment of grip strength using a dynamometer and the Katz activity index related to the need for help in daily activities. This index is easier to assess in the elderly. There is no correlation between the Columbia frailty index and the STS risk score, thereby highlighting that a frailty index adds information to usual risk scores. The evaluation of frailty contributes to the assessment of the biological rather than chronological age. The incremental predictive value of indices adapted to the elderly should be tested in risk scores to improve the risk-benefit analysis of valvular interventions in the elderly.
The assessment of the operative risk using multivariate indices has an impact on decision-making, patient information, assessment of the quality of care, and inclusions in trials. Criticisms have been recently raised against these scores because of their poor calibration. There are indeed important discrepancies between estimated and observed mortality rates in high-risk patients, in particular when using the logistic Euroscore. On the other hand, risk scores have good discrimination properties, i.e. they reliably differentiate low-risk from high-risk patients. The limitations in the predictive value of risk scores in high-risk patients may be due to a number of factors, in particular the under-representation of high risk patients in surgical datasets, the choice of variables and lack of evaluation of functional and cognitive assessment. Operative risk is also influenced by local resources, such as the number of procedures performed and the leaning curve for new techniques. Finally, decision-making should consider the operative risk but also the risk of other techniques, such as TAVI, which should be weighed against the natural history of the disease. Despite their limitations in high-risk patients, the use of risk scores remains necessary since they are the only means to reduce the subjectivity of risk estimation when multiple comorbidities are present. More appropriate scoring systems should be developed. However, a single score will never capture all the component of the risk of interventions, which underlines the importance of clinical judgment through a multidisciplinary approach.
Surgical aortic valve replacement remains the reference treatment of aortic stenosis, including in the elderly, as attested by the fact that guidelines do not provide explicit restrictions in the indication of surgery dye to age itself. One strength of aortic valve replacement is the evidence showing the long-term durability of bioprostheses in the elderly. The risk of surgery is increased by the combination of comorbidities and the consequences of aortic stenosis, in particular on symptoms and left ventricular function. Operative risk can also be increased by local conditions that may be source of complications, such as porcelain aorta, multiple sternotomies, prior coronary artery bypass grafting, and prior chest radiation. Nevertheless, operative mortality rates are lower in recent surgical series, in particular for aortic valve replacement in patients with prior coronary artery bypass grafting. The combination of aortic stenosis and mitral regurgitation should be managed according to the severity and the mechanism of mitral regurgitation. Combined mitral surgery is mainly considered in case of severe organic mitral regurgitation, but its indication should also take into account potential sources of technical difficulties, in particular calcification of mitral annulus. Real contra-indications of surgery are rare. Transcatheter aortic valve implantation is an alternative in patients with severe symptomatic aortic stenosis who are at high risk for surgery according to comorbidities and/or frailty or specific local conditions, in particular iterative sternotomies and porcelain aorta.
In summary, this session reviewed different difficulties in risk-stratification of aortic stenosis in the elderly. The take-home message is the need for a comprehensive assessment of all patient characteristics, in which clinical assessment plays a key role. This underlines the importance of a close interaction between cardiologists and surgeons, as structured in the heart team.
Aortic stenosis in the elderly: difficulties for the clinician
Our mission: To reduce the burden of cardiovascular disease
© 2017 European Society of Cardiology. All rights reserved