Feature: New CV risk guidelines give SHAPE to imaging screening, not far enough

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Coronary calcium is visible as white spots. Image source: Ann Rheum Dis 2003;62:846-850

The new ACCF/AHA (American College of Cardiology Foundation/American Heart Association) guidelines for how to assess cardiovascular risk in asymptomatic adults for the first time have acknowledged the value of coronary artery calcium (CAC) scoring and carotid artery intima-media thickness (CIMT) scanning by ultrasound. Members of the Society for Heart Attack Prevention and Eradication (SHAPE) endorse the new guidelines, but say they need to go further.

"Overall, it's a major change, especially in terms of those at low to intermediate risk who may be suitable to undergo CAC screening," Prediman K. Shah, MD, chairman of the SHAPE scientific board and director of the Cedars-Sinai Heart Institute and Medical Center in Los Angeles, told Cardiovascular Business News.

"The new guidelines say that CAC scoring and CIMT testing 'may be reasonable.' ACC and AHA are clearly conservative and don't want to go out on a limb. It's half of an endorsement, but still a major coup and major acknowledgement," Shah said.

"Their language leaves room for disagreement, but I don't think it will hinder the adoption of CAC screening," Shah said. "Previously, the ACC and AHA argued against it. Now, the people who are undecided about CAC screening will be swayed."

CAC screening received the strongest recommendation of any of the ancillary tests other than the Framingham risk score, said Matthew J. Budoff, MD, a member of the SHAPE II task force and also the ACCF/AHA writing group, in an interview.

"There is a remarkable amount of evidence that has surfaced since 2005, including seven large, prospective studies that show the presence of calcium has a 10-fold predictive risk for future cardiac events. It outperforms C-reactive protein five times out of five in different clinical trials and it outperforms carotid intima-media thickness in the largest of those studies, MESA, where the predictive value was 10-fold for calcium and only two-fold for carotid ultrasound," said Budoff, of the Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center in Torrance, Calif.

While CIMT testing involves no radiation, it is heavily operator dependent, Budoff said. And while CIMT has been elevated in the new guidelines to a similar level as CAC screening, "CAC testing also is recommended for lower risk people, those at 6 to 10 percent at 10 years, and for diabetics, whereas carotid IMT testing is not. CAC screening has three recommendations in three scenarios, whereas carotid IMT has one."

He said that one could argue that the two tests are both useful in intermediate risk, but at lower to intermediate risk or higher risk such as with diabetics, calcium scoring has the indications and CIMT is considered not useful.

"Either way, they are both moving in the right direction and they are both becoming more concordant with the SHAPE guidelines, which propagated the idea that atherosclerosis imaging would help the clinician make decisions about medical therapy and appropriateness," Budoff said.

In 2006, SHAPE guidelines called for CAC scoring and CIMT testing to be incorporated into routine screening for all asymptomatic men aged 45 to 75 years and asymptomatic women aged 55 to 75 years. The SHAPE guidelines became the basis for the Texas Heart Attack Prevention Bill, signed into law in Texas in August 2009, which mandates insurance carriers pay for CAC and CIMT testing. The SHAPE II task force is currently meeting to update their guidelines.

Shah acknowledged the other important elements of the ACCF/AHA guidelines. They do not recommend genomic testing, measurement of natriuretic peptides or measurement of special lipid testing including lipoproteins, apolipoproteins, particle size and density, beyond a standard fasting lipid profile. "The evidence doesn't support that they help in screening," he said.

Regarding reimbursement, UnitedHealthcare has a national policy that pays for calcium scoring for risk stratification, and Medicare pays for calcium scoring for risk stratification in 12 states, Budoff said.

"It is not yet reimbursed by BlueCross BlueShield or Aetna, although they continue to evaluate the data and I hope with these new guidelines, they will reevaluate their policy. I believe the data are stronger today than it was when those policies were instituted," he said.