Dueling Advice: New ACC/AHA Risk Assessment Guidelines, SHAPE II Released on Same Day

Reed Miller

November 15, 2010

November 15, 2010 (Chicago, Illinois) — The major cardiology professional societies are emphasizing the primary role of traditional risk factors in assessing cardiovascular risk in otherwise-healthy people, while the upstart SHAPE organization continues to push for greater acceptance of screening with computed tomography coronary artery calcium scoring (CACS) and ultrasound measurement of carotid intima-media thickness (CIMT).

Here at the American Heart Association 2010 Scientific Sessions, the American College of Cardiology Foundation (ACCF)/American Heart Association (AHA) Task Force on Practice Guidelines released its "2010 guideline for assessment of cardiovascular risk in asymptomatic adults," developed in collaboration with six other specialty societies [1]. Meanwhile, the Society for Heart Attack and Prevention and Eradication, a group of cardiologists and researchers independent of any specialty society, released a summary of the forthcoming SHAPE II guidelines [2].

Two members of the SHAPE II task force were also on the ACCF/AHA writing group: Dr Matthew Budoff (Los Angeles Biomedical Research Center, CA) and Dr Leslee Shaw (Emory University, Atlanta, GA).

Both sets of guidelines reflect the findings of several recent studies confirming the prognostic value of CACS and CIMT, including the Atherosclerosis Risk in Communities Study (ARIC), the National Institutes of Health–sponsored Multi-Ethnic Study of Atherosclerosis (MESA), and the Heinz Nixdorf RECALL Study. The ACC/AHA group is downplaying the relative importance of imaging tests in screening asymptomatic patients, however, while SHAPE is highlighting their potential value.

"There's strong evidence that the basic risk assessment that we've been advocating for years has a very, very strong ability to predict risk," says ACCF/AHA writing group chair Dr Philip Greenland (Northwestern University, Chicago, IL). "When new tests compete for attention, we have to ask, 'Do they add any new information?' "

ACC immediate past president Dr Alfred A Bove (Temple University, Philadelphia, PA) told heartwire that he supports the ACCF/AHA writing group's emphasis on the "basic clinical criteria to adjudicate risk on the front line." He also pointed out that the statement is timely, because the ACC is part of a long-term effort to shift the US healthcare system from a fee-for-service system, which he says rewards overutilization of technologies such as imaging tests, to a system that reimburses providers based on outcomes.

In contrast, "SHAPE II advocates widespread adoption of noninvasive imaging tests . . . to assess and reduce an asymptomatic individual's heart-attack risk instead of solely relying on measuring risk factors such as cholesterol," the organization states in a release.

Clarifying Intermediate Risk

The difference in the two groups' stance on imaging is partly just a difference in emphasis. They agree that imaging tests have a role in clarifying the risk of individuals considered at intermediate risk based on traditional risk factors such cholesterol, blood pressure, age, gender, diabetes, smoking, and family history.

The ACCF/AHA guidelines state that CIMT may be beneficial in people at intermediate risk, but only if the "required equipment, technical approach, and operator training and experience for performance of the test [are] carefully followed to achieve high-quality results."

The ACCF/AHA writing group concludes that CACS may be appropriate for those with diabetes aged 40 years and over and possibly in those of low to intermediate risk. The writing group assigns both tests to category IIa with evidence level B, indicating that the test is reasonable in intermediate-risk patients and that the benefits outweigh the risks, but more studies with focused objectives are needed before the group can definitely recommend that the test should always be performed.

SHAPE advocates CIMT or CACS for intermediate-risk people aged 45 to 80. It also recommends screening for men 35 and older who are diabetic or have a family history of premature coronary disease. The first SHAPE guidelines, published in 2006, recommended screening with CACS and CIMT for all at-risk men between the ages of 45 and 75 and all women aged 55 to 75 years unless they had cholesterol <200 mg/dL, blood pressure <120/80 mm Hg, and no diabetes, smoking, family history, or metabolic syndrome. SHAPE II sets the cutoff for what counts as a positive CIMT test to the 75th percentile or higher, whereas the 2006 SHAPE I guidelines set it at 50%.

The new SHAPE recommendations also expand the application of C-reactive protein (CRP) tests by recommending the test for all intermediate- and high-risk individuals and elevating the patient's risk category if CRP >3 mg/L. CRP testing was a "hot issue" in the ACCF/AHA writing group discussions, according to writing group member Dr Sidney Smith (University of North Carolina, Chapel Hill), but the committee found that the test generally adds little prognostic information to traditional risk factors. However, the ACCF/AHA guidelines state that C-reactive protein testing may be useful in intermediate-risk men aged 50 or younger and women aged 60 or younger, and it can help decide whether to prescribe statins to some older patients. The writing group does not recommend CRP testing for high- or low-risk individuals.

The writing group found no benefit to intermediate-risk patients from genetic testing, "advanced" lipid testing, natriuretic-peptide–level testing, coronary CT angiography, MRI for the detection of vulnerable plaques, or stress echo.

The separate guidelines appear to diverge on the question of serial testing. SHAPE II recommends repeat CACS or CIMT every three to five years, depending on the level of risk assessed at the first test. However, the ACCF/AHA writing group concludes, "Serial scanning of carotid IMT is challenging in individual patients across brief time horizons due to variability in measurement in relation to the rate of disease progression and is therefore not recommended in clinical settings." For CACS, the group found, "Although preliminary data suggest that a calcium scan progression rate of >15% per year is associated with a 17-fold increased risk for incident CHD events, there are no data demonstrating that serial CAC testing leads to improved outcomes or changes in therapeutic decision-making."

The ACCF/AHA writing group "felt that it is reasonable" to advise everyone to begin global risk score measures, including blood-pressure and cholesterol tests, starting at age 20 and then every five years, but recognizes that the starting point is "arbitrary."

According to the ACCF/AHA writing group, "There is little information available in the research literature to suggest the optimal timing to initiate risk assessment in adults. There is also limited information to inform decisions about frequency of risk assessment in persons who are determined to be at low or intermediate risk on initial risk assessment. High-risk persons are likely to initiate treatment strategies, and repeat risk assessment is likely to be a standard component of patient follow-up. More research on the optimal timing to begin risk assessment and repeat risk assessment in the asymptomatic patient is warranted."

Other Societies Weigh In

The ACCF recently released appropriateness criteria for cardiac computed tomography, developed by representatives of eight societies, which support coronary calcium testing in intermediate-risk patients. Also, the Society of Atherosclerosis Imaging and Prevention (SAIP) and International Atherosclerosis Society (IAS) published appropriateness criteria for CIMT online November 5, 2010 in Atherosclerosis [3]. These criteria deem the detection of CHD risk among intermediate-risk patients, those with metabolic syndrome, and older patients generally appropriate, but the SAIP/IAS writing group did not deem any serial testing indications appropriate, and most applications of CIMT in low-risk patients and high-risk patients were also deemed inappropriate.

As previously reported by heartwire , the first SHAPE guidelines created some controversy because they were created apart from the traditional American Heart Association or American College of Cardiology guidelines system and were first published in a supplement in the American Journal of Cardiology sponsored by Pfizer. The SHAPE II authors say they will publish the new recommendations in a major peer-reviewed journal.

SHAPE II task force member Dr Harvey Hecht (Lenox Hill Heart and Vascular Institute, New York, NY) told heartwire he believes that these studies vindicate the authors of the first SHAPE guidelines. "Back then, we were really ahead of the curve and heavily criticized for it, but the evidence-based medicine that people have asked for to justify what we said in SHAPE I has really been provided in the intervening four years."

Dr James Min (Weill Medical College of Cornell University, New York, NY), who is not part of the SHAPE task force, agrees that SHAPE II reflects the current state of the science. "There's been an enormous amount of data to support earlier detection of patients at risk for coronary heart disease events, and certainly MESA and Heinz-Nixdorf did great things to confirm what all of the prior registries had demonstrated--namely, that if you have a high coronary calcium score, you have a 10-fold increased risk of coronary heart disease events," Min told heartwire . As reported by heartwire , the Texas Heart Attack Prevention Bill, which mandates health-benefit plans to provide coverage for certain screening tests for early coronary disease, grew out of SHAPE. "That should just be the beginning. We need to approach all states so people across the country have access to risk-stratification evaluation," Min said.

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