Editor's Note: This is Part I of a two-part Expert Analysis. Go to Part II.

Introduction

Aortic stenosis (AS) is a disease mainly affecting the elderly, and definitive management requires procedural intervention. The lack of definitive management and poor outcomes are often thought to be age-related. Navigating the nuances of this situation to achieve a satisfactory outcome makes the assessment and treatment of this population both complex and rewarding. The prevalence of AS is 2.8% among adults over age 75 years and 9.8% in octogenarians, respectively.¹ There is currently no preventive treatment for AS, and the prevalence is expected to double in the next 20 years along with a rise in life expectancy.² It is increasingly important for clinicians assessing patients with AS to familiarize themselves with special considerations needed to address the geriatric population while being mindful that older adults are a heterogeneous group possessing varying amounts and degrees of concomitant age-related medical and psychosocial concerns.

Assessment of the Patient in a Clinical Setting

The assessment of the geriatric patient with AS includes history taking, a physical exam, and review of data. Data needed to be reviewed includes electrocardiogram (ECG), labs, echocardiography/computed tomography (CT) for valve size measurements, and information regarding related cardiac conditions.³ Taking a patient's history is particularly important for eliciting symptoms linked to decreased survival⁴ and evaluating the need for aortic valve replacement (AVR).^3,5 It is vital to ascertain if a patient is symptomatic. However, there can be challenges to obtaining this information from members of the geriatric population. The ability to relate symptoms requires hearing and the use of language. Conditions such as a hearing impairment, stroke with language deficits, or dementia may impair communication. Allotment of more time for the interview may be needed to allow for a thorough evaluation. Elderly patients who do not express themselves can be inappropriately labelled as asymptomatic. Family members or caregivers can comment on syncopal episodes, unexplained falls, and nonverbal cues for chest pain and dyspnea. The assessment of symptoms can also be impacted by reductions in physical activity attributed to comorbid conditions or mistakenly attributed to normal aging. In patients with severe AS who deny symptoms and can exercise, there is evidence supporting the safety and utility of provocative exercise testing, monitored by an experienced physician, for risk assessment.³ Testing can help with therapeutic decision making in patients unaware of the physical limitations posed by AS.

Assessment of Concomitant Atherosclerotic Disease

Atherosclerosis, like AS, is age-associated and shares a pathogenic link at both cellular and molecular levels.^6,7 Thus, clinicians can expect a high coexistence of both processes. Significant coronary artery disease (CAD) is present in 25% of patients with asymptomatic severe AS and increases to 40-80% in patients presenting with symptom of angina.⁸ Concomitant CAD and AS carries diagnostic, prognostic, and therapeutic implications. For example, symptoms out of proportion to valve characteristics and hemodynamics should prompt an assessment for CAD and treatment of CAD alone may resolve symptoms. However, it is often challenging to determine which entity is responsible and both processes may work synergistically to decrease myocardial perfusion.

Combined coronary artery bypass graft surgery (CABG) and AVR are common in the elderly.⁹ This has consequences as patients undergoing combined surgery have lower short- and long-term survival and a higher rate of surgical complications.¹⁰ The elderly are also more likely to have presented with previous clinically significant disease and already have had CABG. Redo surgery is associated with increased bleeding, injury to bypass grafts, and a higher rate of early morbidity and mortality. Transcatheter aortic valve replacement is playing an emerging role to prevent the postoperative morbidity associated with repeat sternotomy, and can be performed in conjunction with percutaneous coronary intervention (PCI).

Peripheral arterial disease (PAD) is an age-related atherosclerotic process that carries implications for the treatment of AS. Lower extremity PAD is present in up to 14.5% in patients over 70.¹¹ Its presence is especially important to note if transcatheter therapies are being considered. Carotid artery stenosis (CAS) is another atherosclerotic process related to AS, and its presence is linked to the severity of AS.¹² In patients undergoing cardiac surgery, both symptomatic and asymptomatic moderate-to-severe CAS carries an increased stroke risk estimated between 7.4% and 9.1%.¹³ There is no clear evidence that carotid intervention prior to cardiac surgery lowers stroke risk, especially among women.^14,15 Clinicians treating geriatric populations with AS will simultaneously need to assess and manage concomitant age-related atherosclerotic disease, which has implications for the diagnosis of symptoms, risk of intervention, and choice of procedural management.

Assessment of Other Cardiac Conditions

Left ventricular (LV) dysfunction, both systolic and diastolic, can coexist with AS as the result of valvular disease itself or a consequence of a coexisting process, most commonly hypertension or ischemic heart disease.¹⁶ LV dysfunction can exert an influence on the hemodynamic parameters, mean gradients and peak velocities, used to classify AS severity. Two subgroups of AS in which measurements can be misleading are: 1) low-flow, low-gradient AS; and 2) paradoxical low-flow, low-gradient AS. The latter tends to affect elderly women with hypertension. In these cases, it is recommended that aortic valve area is primarily used to assess severity as the prognosis is generally poorer when the aortic valve area is <1.0 cm².³ In patients with low-flow, low-gradient AS, an important component to preoperative assessment is determining if there is contractile reserve to predict a favorable outcome to AVR. This can be determined by low-dose dobutamine testing using measurements from echocardiography or invasive hemodynamics.³

Degenerative disease of the conduction system is another age-related cardiac process that can be identified with ECG screening. The proximity of the left bundle branch to the aortic valve makes elderly patients with AS, especially those with preexisting conduction disease, more vulnerable to iatrogenic related conduction abnormalities. Identifying preexisting conduction abnormalities helps predict who will need a pacemaker intraoperatively and long term.¹⁷ Atrial fibrillation (AF) is a common age-related dysrhythmia that may be present in patients with AS. AF can precipitate valve-related symptoms and exerts a negative effect on procedural outcomes in SAVR.¹⁸

Conclusion

The patient-centered assessment of the geriatric population with AS is predicated on the concept that placement of a new valve should be considered a tool to improve the quality of life of the elderly person who previously had AS and allow him or her to continue to enrich the lives of his or her family and community. Decision making in this population is complex and best aided with a thorough assessment. Clinicians should evaluate symptoms, assess the goals of the patient, and estimate each individual patient's risk within a biologic and psychosocial age-related context. Cardiologists should strive for a working knowledge of issues facing the geriatric population and aim to build a heart team utilizing clinicians from multiple disciplines. With the change in demographics and projected rise in the prevalence of AS, there is a need for increased research, interdisciplinary collaboration, and awareness of geriatric issues as part of a movement towards a comprehensive assessment of the geriatric population with AS.

References

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7. Otto CM, Kuusisto J, Reichenbach DD, Gown AM, O'Brien KD. Characterization of the early lesion of 'degenerative' valvular aortic stenosis. Circulation 1994;90:844-53.
8. Griffin BP. Manuel of Cardiovascular Medicine. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2012.
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10. Beach JM, Mihaljevic T, Svensson LG, et al. Coronary artery disease and outcomes of aortic valve replacement for severe aortic stenosis. J Am Coll Cardiol 2013;61:837-48.
11. Selvin E, Erlinger TP. Prevalence of and risk factors for peripheral arterial disease in the United States: results from the National Health and Nutrition Examination Survey, 1999-2000. Circulation 2004;110:738-43.
12. Novo G, Guarneri FP, Ferro G, et al. Association between asymptomatic carotid atherosclerosis and degenerative aortic stenosis. Atherosclerosis 2012;223:519-22.
13. Naylor AR, Bown MJ. Stroke after cardiac surgery and its association with asymptomatic carotid disease: an updated systematic review and meta-analysis. Eur J Vasc Endovasc Surg 2011;41:607-24.
14. Paraskevas KI, Mikhailidis DP. Carotid artery stenosis and heart valve surgery: a complex scenario. Angiology 2011;62:597-600.
15. Engwenyu LR, Jawad W, Patel A, et al. Gender Considerations in Peripheral Vascular Disease. In: Mieszczanska HZ, Velarde GP, eds. Manual of Cardiovascular Disease in Women. London: Springer London Ltd; 2014: 379-97.
16. Yamasaki N, Kitaoka H, Matsumura Y, Furuno T, Nishinaga M, Doi Y. Heart failure in the elderly. Intern Med 2003;42:383-8.
17. Matthews IG, Fazal IA, Bates M, et al. In patients undergoing aortic valve replacement, what factors predict the requirement for permanent pacemaker implantation? Interact Cardiovasc Thorac Surg 2011;12:475-9.
18. Banach M, Goch A, Okonski P, et al. Relation between postoperative mortality and atrial fibrillation before surgical revascularization—3 years follow-up. Thorac Cardiovasc Surg 2008;56:20-3.

Keywords: Aged, Angina Pectoris, Aortic Valve, Aortic Valve Stenosis, Arrhythmias, Cardiac, Atrial Fibrillation, Biological Products, Cardiac Surgical Procedures, Caregivers, Carotid Stenosis, Cooperative Behavior, Coronary Artery Bypass, Coronary Artery Disease, Cues, Decision Making, Dementia, Dobutamine, Dyspnea, Echocardiography, Electrocardiography, Hearing Loss, Heart Conduction System, Hemodynamics, Hypertension, Iatrogenic Disease, Life Expectancy, Lower Extremity, Medical History Taking, Motor Activity, Percutaneous Coronary Intervention, Peripheral Arterial Disease, Prevalence, Prognosis, Quality of Life, Risk Assessment, Sternotomy, Stroke, Syncope, Tomography, Transcatheter Aortic Valve Replacement

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