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This is Part I of a two-part article on treatment of acute coronary syndrome in the older population. Part I analyzes the differential utilization of invasive therapies with respect to age and heart disease. Part II (to be published in the next issue of Clinical Geriatrics) will summarize information from the literature on acute coronary syndrome outcomes from invasive treatments (percutaneous coronary interventions or coronary artery bypass grafting) among older persons.
Acute coronary syndromes (ACS) account for 35% of deaths among people older than 65 in the United States.1 Cardiovascular morbidity and mortality rates rise rapidly among people over 75, an age group that accounts for only 6% of the U.S. population but 60% of myocardial infarction (MI)-related deaths.2 Although the management of patients with ACS has evolved rapidly with the development of new therapeutics and strategies of care, improved survival and gains in life expectancy are mainly realized in younger people and in men.3 The elderly are known to be at high risk of ACS, but community practice patterns continue to demonstrate less use of cardiac medications and invasive care for elderly people than for others.4
Limited randomized clinical trial data to guide acute care in elderly patients, coupled with lingering uncertainty about benefit and risk with advanced age, likely explain this practice.5 Patients over 75 years of age accounted for just 9% of all patients enrolled in trials, and more than half of all trials for coronary disease in the past decade failed to enroll any patient over 75.6 Although explicit age exclusions in clinical trials have become less common since 1990, age-based exclusions continue.7 For gains in quality life-years after onset of ACS to continue, survival from acute heart disease will need to extend to the very elderly population.8 A basic understanding of how competing treatment strategies in ACS influence outcomes in this vulnerable subgroup remains elusive.
The purposes of this review are to: (1) analyze the differential utilization of invasive therapies with respect to age and heart disease (Part I); and (2) summarize information from the literature on ACS outcomes from invasive treatments (percutaneous coronary intervention [PCI] or coronary artery bypass grafting [CABG]) among older persons (Part II). Through this analysis, we hope to provide an improved understanding of efficacy and appropriateness of ACS treatment in the elderly.
It is understandable that PCI, as a relatively less-invasive procedure, would be utilized more quickly than CABG, but the patterns of substitution of PCI for CABG raise the broader question of whether older persons are provided the revascularization treatment that benefits them the most.
The inclination of older people to utilize technologies for medical treatment is often constrained informally by the provider's or patient's assessment of marginal benefit from aggressive treatment. Yet, as older persons live longer and remain healthier, such implicit and explicit constraints are challenged or modified. Fuchs9 described the rate of utilization of selected health technologies among the elderly population in the United States for three procedures (cardiac catheterization, CABG, and PCI) related to coronary artery disease (CAD) between 1987 and 1995. Rates of all three procedures increased markedly for both genders and all age groups during this period. The increase was higher among persons age 80 and older relative to persons age 65 to 79 (due to the initially lower use rates per 100,000 people among persons age 80 and older in 1985).
To consider more recent trends in utilization, we examined data from the Healthcare Cost and Utilization Project (HCUP) database (HCUPNET) since 1997 combined with census population data. Figures 1a-1c show CABG and PCI procedure rates per 100,000 by age group through 2005, while Figures 1d-1f show the corresponding rates of utilization since 1998. The rates of revascularization are relatively stable for persons age 45-64, with only a modest decline in CABG rates since 1997. In contrast, rates of PCI increased for persons over age 65 while CABG rates declined fairly consistently from 1997 through 2005. The utilization of PCI and decline in rates of CABG were particularly strong for persons age 85 years and older, though the strength of the effects are attributable in large part to the relatively small procedure rates for this age group in 1997.
Over the past few decades, longevity has been increasing. It is predictable, therefore, that rates of revascularization in the form of PCI are increasing in the older population. In sharp contrast, it is remarkable that CABG rates are dropping steadily in this group, despite an elderly population that is healthier on average. The data are consistent with a paradigm of increased frequency of PCI replacing CABG (not delaying it). It is understandable that PCI, as a relatively lessinvasive procedure, would be utilized more quickly than CABG, but the patterns of substitution of PCI for CABG raise the broader question of whether older persons are provided the revascularization treatment that benefits them the most.
In current clinical practice, older patients with ACS appear to be less likely to undergo invasive procedures than younger patients.10-14 The reasons for a less-invasive approach as age increases include misdiagnosis, perceived frailty, and comorbid conditions leading to a two-edged bias, as well as underestimation of patient's risk without interventional treatment and overestimation of patient's risk with invasive treatment. However, a study of procedures performed in Olmsted County, Minnesota, from 1990 to 2004 showed that a 69% increase in PCI accompanied by a 33% decrease in CABG resulted in a net increase of 24% in total revascularization.15 Utilization among older adults increased more steeply than among younger persons. Thus, in the community setting, an increasing proportion of PCI, more than of CABG, is performed in elderly persons. These findings are likely due to a combination of several factors, including demographic changes occurring in the population16 and perception of the upper age limit for CABG.17
The initial cardiac evaluation begins with a determination that symptoms indicate the presence of an ACS. Atypical symptoms (defined as absence of chest pain) occur more often among older patients with ACS. The National Registry of Myocardial Infarction (NRMI) contributed a significant data set describing community elderly with ACS. In this registry, only 40% of those 85 and older had chest pain on presentation as compared with 77% of those younger than 65. Although chest pain remains a common presentation of ACS regardless of age, elderly patients were more likely to present with dyspnea (49%), diaphoresis (26%), nausea and vomiting (24%), and syncope (19%) as a primary complaint; hence, MI may go unrecognized18 (Table). Underscoring the presenting symptom of dyspnea, the likelihood of signs of heart failure (pulmonary rales, jugular venous distention) also increases with age. Not surprisingly, just over half of the very elderly in the NRMI were admitted with an initial diagnosis of MI, rule-out MI, or unstable angina (56% of those 85 or older), yet all of these patients were determined at discharge to have had an MI.
In the Framingham cohort, silent or unrecognized infarctions were also more common in the elderly, which suggests that patients themselves fail to attribute atypical symptoms to a cardiac cause. Whereas silent or unrecognized infarctions accounted for 25% of all MIs, they accounted for up to 60% of MIs in patients over 85.18,19 Acute coronary syndrome is more likely to develop in older patients who have another acute illness or worsening of a comorbid condition (eg, pneumonia, chronic obstructive pulmonary disease, a fall). These “secondary” coronary events occur in the setting of increased myocardial oxygen demand or hemodynamic stress in patients with underlying atherosclerotic disease. Thus, nonspecific symptoms and comorbid diseases may mask the initial presentation and contribute to treatment delays. Atypical presentations have been shown to portend a worse prognosis (a threefold higher risk of inhospital death [13% vs 4%]), in part because of delays in diagnosis and treatment and less use of evidencebased medications.18,19
Although age itself is a nonmodifiable risk factor, certain age-associated conditions (eg, anemia, kidney disease, frailty, disability, cognitive dysfunction) may be understood as distinct from age. Diminished organ reserves and altered functional and cognitive status influence disease presentation, treatment, and recovery. The term “frailty” has been used to describe a state of declining reserves in strength and function that occurs in older populations. Frailty, distinct from cardiovascular disease, disability, or comorbidity, overlaps with these conditions in numerous ways. Using one definition, 6.9% of community-dwelling elderly persons over age 65, 9.5% between age 75 and 79, 16.3% between age 80 and 84, and 25% of persons age 85 or older were found to be frail.20 In addition to having more comorbid conditions (eg, diabetes mellitus, hypertension), frail individuals demonstrate inflammatory dysregulation, with baseline elevation in inflammatory markers (C-reactive protein and interleukin-6), all of which may contribute to ACS risk and outcomes.21 Domains for mobility, physiological reserves, nutritional status, and function serve as important metrics for risk assessment in the elderly. In addition, those who take a broad view of health in the older individual include social, cognitive, and psychological issues in the construct. In the Heart Protection Study, 34% of community-dwelling elderly people over 70 years old had mild cognitive impairment.22 Altered cognition, hearing, and vision may delay presentation, impair communication, and affect decision-making if the person is unlikely to be able to adhere to a plan of treatment or consent to a burdensome procedure. Although various factors account for delay in diagnosis of CAD in the elderly, it is critical to understand the current natural history of ACS in this vulnerable population.
The Global Registry of Acute Coronary Events (GRACE) is a large, multinational, prospective registry in which 109 hospitals in 14 countries collect baseline characteristics and clinical management, therapeutic, and outcomes data on patients admitted with a presumptive diagnosis of ACS with follow-up to one year. Established in 1999, GRACE enrolls both patients with non-ST elevation myocardial infarction (NSTEMI) (45% of total enrollment) and those with ST elevation myocardial infarction (STEMI) (55% of total enrollment), with the only exclusion being another major diagnosis concurrent with the coronary syndrome. The baseline characteristics, treatments, and outcomes of 12,000 international non-ST elevation ACS patients enrolled in GRACE between 1999 and 2004 were evaluated.4
In current practice, patients age 65 and younger with ACS have a 3.1% chance of dying during their hospitalization, but this risk climbs to 18.1% for patients 85 years of age and older23 (Figure 2). Among hospital survivors, the higher risk in the elderly continues from 30 days to one year. The one-year death rate from GRACE patients 75 to 84 years of age is 15%, and for patients 85 and older the mortality was 25%, underscoring the continued risk after acute care. Although these vulnerable people may be succumbing to comorbid conditions, it is a reasonable assumption that progression of heart disease significantly influences this increasing mortality with age and time.
Observational ACS data suggest that: (1) there is an age-associated differential therapy; (2) ACS is masked by comorbid conditions; and (3) there is extraordinary age-associated mortality with ACS. Extrapolating these observations to clinical practice creates a potential therapeutic opportunity for realizing healthcare benefits for older persons with CAD. Although the bedrock of therapy is currently medical, a critical review of the literature is important to understand whether interventional therapeutic strategies may provide a health benefit to this vulnerable population. n
METHOD OF PARTICIPATION/SUCCESSFUL COMPLETION
To be eligible for documentation of credit, participants must read all article content, log on to www.princetoncme.com to complete the online post-test with a score of 70% or better, and complete the online evaluation form. Participants who successfully complete the post-test and evaluation form online may immediately print their documentation of credit. Please e-mail firstname.lastname@example.org or call (609) 371-1137 if you have questions or need additional information.
SPONSOR This activity is sponsored by NACCME.
TARGET AUDIENCE Internists, family practitioners, geriatricians, cardiologists, and others who care for older patients.
METHOD OF PARTICIPATION/SUCCESSFUL COMPLETION To be eligible for documentation of credit, participants must read all article content, log on to www.princeton cme.com to complete the online post-test with a score of 70% or better, and complete the online evaluation form. Participants who successfully complete the post-test and evaluation form online may immediately print their documentation of credit. Please e-mail email@example.com or call (609) 371-1137 if you have questions or need additional information.
ACCREDITATION MD/DO This activity is sponsored by the North American Center for Continuing Medical Education (NACCME). NACCME is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. NACCME designates this educational activity for a maximum of 1 AMA PRA Category 1 Credit™. Physicians should only claim credit commensurate with the extent of their participation in the activity. This activity has been planned and produced in accordance with the ACCME Essential Areas and Policies.
LEARNING OBJECTIVES Upon completion of this educational activity, participants should be able to:
1. Understand the prevalence of acute coronary syndrome in older persons.
2. List the four most common symptomatic presentations of acute coronary syndrome in the elderly.
3. Describe the differential utilization of invasive acute coronary syndrome therapies in older persons.
4. Explain the one-year mortality risk in the elderly once they have been hospitalized with the diagnosis of acute coronary syndrome.
DISCLOSURES All those in a position to control content of continuing education programs sponsored by NACCME, LLC are required to disclose any relevant financial relationships with relevant commercial companies related to this activity. All relevant relationships that are identified are reviewed for potential conflicts of interest. If a conflict is identified, it is the responsibility of NACCME to initiate a mechanism to resolve the conflict(s). The existence of these interests or relationships is not viewed as implying bias or decreasing the value of the presentation. All educational materials are reviewed for fair balance, scientific objectivity of studies reported, and levels of evidence.
Planning Committee: T. Levy, NACCME, and C. Ciraulo and S. Gephart, HMP Communications, have disclosed no relevant financial relationship with any commercial interest.
Editor: M. Edwards has disclosed no relevant financial relationship with any commercial interest.
Faculty: Dr. Sheridan has disclosed that he is a consultant for Pfizer.
Dr. Stearns, Dr. Massing, Dr. Stouffer, Ms. D'Arcy, and Dr. Carey have disclosed no relevant financial relationship with any commercial interest.
Clinical Reviewer: Dr. Christmas has disclosed no relevant financial relationship with any commercial interest.