Screening Asymptomatic Adults for Cardiovascular Disease - A New Guideline Emphasizes the Global Risk Score
Pub Date: Nov. 15, 2010
Author: Marian Limacher, M.D., FAHA, FACC
Greenland P, Alpert JS, Beller GA, et al. 2010 ACCF/AHA guideline for assessment of cardiovascular risk in asymptomatic adults: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Developed in collaboration with American Society of Echocardiography, American Society of Nuclear Cardiology, Society of Atherosclerosis Imaging and Prevention, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, and Society for Cardiovascular Magnetic Resonance. Circulation. 2010: published online before print November 15, 2010, 10.1161/CIR.0b013e3182051b4c.
The 2010 American College of Cardiology Foundation/American Heart Association Guideline for Assessment of Cardiovascular Risk in Asymptomatic Adults provides a valuable tool for clinicians. The authors have succeeded in presenting a balanced review of the available evidence to support their recommendations. Moreover, they clearly delineate and apply the criteria that form the basis for their decisions. The evolution of guideline formation is reflected in the requirement that new risk factors or markers must demonstrate added predictive information beyond a standard risk assessment profile. The document's description of the methods to assess predictive models is a succinct explanation that can be recommended to all for review. As acknowledged by the committee, they generally could not find sufficient evidence for the cost-effectiveness of these tests or methods to be able to provide such information in this document. This gap is serious as the overall recommendations would ideally not be widely implemented without thoughtful evaluation of the individual, system, and national costs of such strategies. Thus, further and prompt attention to such analyses should be a research priority.
Another notable element of the guideline is the inclusion of comments regarding how useful an individual marker has been in motivating patient behavior or guiding therapy. Unfortunately, in many cases, data are lacking regarding any proof that informing patients of specific testing results actually changes patient behaviors to modify a high-risk finding. As with cost-effectiveness analyses, research targeting this aspect of prevention should also become a priority.
What are the major recommendations for screening?
Defining adults as age 20 and older, the committee strongly re-endorses the concept of global risk assessment using a validated risk score as the primary approach to individual screening for cardiovascular disease (CVD). This strategy permits assignment of a category of risk to use to advise patients and recommend appropriate interventions, aligning the intensity of the intervention with the severity of risk. This emphasis on global risk assessment may not be new, but reflects the understanding that identifying the level of CVD risk is the basis for deciding on other testing. Although the Framingham Risk Score may be most appropriate for adults in the United States, all validated multivariable risk scoring systems are provided (Table 2) with active online links allowing for individual preferences and application.
After obtaining a global risk assessment, the guideline supports the use of some additional markers or testing while recommending against the use of others. Family history of CVD should be assessed in everyone (Class I). Urinary albumin and a resting 12-lead electrocardiogram (ECG) are Class IIa recommendations for diabetic or hypertensive patients, but Class IIb for those at intermediate CVD risk without hypertension or diabetes. Hemoglobin A1c is recommended as a reasonable measurement (i.e., Class IIb), and may be particularly applicable in our growing population of overweight and obese individuals. High-sensitivity C-reactive protein (CRP) may be useful (Class IIa) for intermediate-risk men age 50 or younger or women age 50 or younger. This recommendation is concordant with the conclusions of the Canadian Cardiovascular Society, which published updated guidelines in 2009. However, the guideline indicates that for other ages (men younger than 50 or women younger than 60), CRP measurement may be reasonable for intermediate risk subjects (Class IIb) but for high-risk or low-risk individuals, CRP is not recommended (Class III). The simple and available measurement of the ankle-brachial index is considered a Class IIa recommendation for asymptomatic adults. Lipoprotein-associated phospholipase A2 received a Class IIb recommendation for measurement only in the intermediate-risk asymptomatic adult.
Imaging studies are addressed in considerable detail as appropriate for the level of interest and available of these techniques. The guideline concludes that echocardiography to detect left ventricular hypertrophy may be considered (Class IIb) for patients with hypertension but not in other asymptomatic adults. Carotid intima-media thickness by ultrasound may have value and is rated as a Class IIa recommendation, but the well-described limitations in standardization, training, and reproducibility may make this recommendation less practical. Exercise ECG testing may be considered for intermediate-risk adults but stress echocardiography is not recommended. Myocardial perfusion imaging may be considered when other assessments suggest high risk for coronary heart disease but not for evaluation of low- or intermediate-risk asymptomatic adults. The body of evidence supports measuring coronary calcium score in asymptomatic adults at intermediate CVD risk (Class IIa) or low to intermediate risk (Class IIb), but not in low-risk individuals.
On the other hand, genotyping, other lipoprotein and apolipoprotein measurements, natriuretic peptides, hs-CRP for high- or low-risk adults, brachial/peripheral flow-mediated dilation, measurement of arterial stiffness, contrast computed tomography angiography and plaque imaging by magnetic resonance imaging are not recommended (Class III). The lack of support for these tests may change as more evidence is acquired. However, future recommendations will have to fully consider cost-effectiveness before reclassifying them.
With this updated guideline, clinicians have practical, evidence-supported recommendations to use to assess asymptomatic adults for future CVD risk. Most decisions should be based on the initial global risk score. Further recommended tests may be appropriate, particularly in those at intermediate risk, when further discrimination will determine the need for and intensity of interventions. The challenge lies with how these practice recommendations will be implemented and acted upon and then whether CVD outcomes will be reduced. Measuring the effectiveness of these recommendations should be a focus for ongoing research and policies.
- Genest J, McPherson R, Frolich J, et al. 2009 Canadian Cardiovascular Society/Canadian guidelines for the diagnosis and treatment of dyslipidemia and prevention of cardiovascular disease in the adult - 2009 recommendations. Can J Cardiol 2009;25(10):567-579.
-- The opinions expressed in this commentary are not necessarily those of the editors or of the American Heart Association