New Evidence Bolsters Use of Heart Scans
Controversial Calcium Tests Help Predict Coronary Risk
For Many People, Study Says

(Article appeared in THE WALL STREET JOURNAL)

Few debates in medicine have been more intense. Hundreds of thousands of Americans have shelled out $200 and more to get their coronary arteries scanned for calcium, at shopping malls, church basements and in tractor-trailers hauling imaging machines. Critics have derided the tests as a scam. But proponents have touted the images of calcium deposits as the ultimate predictor of heart disease.

Now there is evidence that CT scans for calcium can play a significant role in predicting cardiac deaths and making treatment decisions for the millions of people in the middle-range of coronary risk. New research shows the scans don't appear to be of much use in high-risk patients with multiple factors like combined high cholesterol, smoking and previous cardiac events. Nor do they seem to be useful for people whose risk is minimal.

But for those middle-range people - about 40% of adults - whose known risk of heart attack or cardiac death is calculated at 10% to 19% over 10 years, using a standard risk-assessment method, the CT imaging tests appear to have significant benefit. The new conclusions are derived from research recently conducted at Northwestern University's Feinberg School of Medicine in Chicago, the University of California at Los Angeles and the University of Southern California. A report of their findings was published in this week's edition of the Journal of the American Medical Association.

The findings are particularly significant because treatment decisions are the hardest to make for patients of middle risk. If a large amount of coronary calcium in such people is found to be an important predictor of future coronary disease, doctors might be able to make faster and more aggressive treatment decisions such as prescribing drugs or ordering diet, exercise and other lifestyle changes.

Patients' preliminary heart-attack risk is usually measured by the so-called Framingham risk score, a predictive scale that includes well-accepted risk factors like cholesterol, smoking, diabetes, family history and blood pressure that derive from a landmark heart study.

The new study focused on 1,312 people in California - all of them over 45 years old and most in their 60s - who got CT scans to measure coronary calcium. Researchers followed them for an average of seven years, and 84 of them had a heart attack or died from cardiac causes during that time. The question the researchers focused on was whether the imaging test could help improve the frustratingly imprecise traditional "risk-factor" analysis. After all, about 35% of heart attacks occur in people whose total cholesterol is below the accepted standard of 200. The conclusion was that the "calcium score" from the CT does alter that analysis, and can lead to more intensive treatment.

"There has been a sense of befuddlement about the intermediate-risk patient," says Philip Greenland, chairman of preventive medicine at Northwestern and an author of the study. "They don't quite meet the threshold for drug therapy. But if with a high calcium score they move up into the higher classification of predicted risk, they become a candidate for drugs." He recommends the CT scan be considered only after evaluation by a doctor, including cholesterol measurement.

Will Insurers Pay?

Health insurers generally don't cover the calcium CT scans. But now that there is a major study to support it, health plans will in all likelihood start covering the test if a doctor prescribes it. They are unlikely to cover the scan for people who just want to find out their calcium scores, though. Most doctors recommend that anyone who elects to get a scan, do so at a medical center, not, say, a mall or county fair.

The researchers' conclusions apply generally only to people over 45, because a lower age generally means a far lower risk. They also don't apply to people with diabetes, who currently are believed to be a significantly higher risk.

Rather, they apply to midrange people such as these: Someone with fairly high LDL cholesterol of 150 or 160, but with no other risk factors, and no protective effect from high HDL, or "good" cholesterol. Or it could apply to a smoker who lacks other risk factors and has low cholesterol and blood pressure.

In such people, researchers found, a high calcium score of 300 or more bumps them up into the higher-risk category of people who need intensive lifestyle changes and, possibly, drugs. A score of more than 300 puts people at least in the top 10-percentile of plaque buildup in heart arteries.

David Van Zandt, dean of the Northwestern University Law School in Chicago, is a patient who may benefit from the scan. With a family history of heart disease and borderline high cholesterol, he was a classic middle-risk person at age 50, until he recently got a CT scan, which showed heavy plaque. His doctor put him on a statin drug, and he overhauled his eating and exercise habits. "Now, almost nothing with saturated fat passes my lips," he says.

The new research, if widely accepted, could prove a boon to manufacturers of cholesterol-lowering statin drugs, such as Pfizer Inc., which makes Lipitor, and Merck & Co., which makes Zocor. Theoretically, the new knowledge could also lead to invasive tests like ngiograms or even major steps like stents or surgery to open up coronary arteries. It is because of the danger of possible "overtreatment" that the debate over CT scans has been so intense.

Longtime Dilemma

The longtime dilemma over this issue has stemmed from a curious physiological phenomenon. Calcium forms to protect heart arteries from the fatty plaque that builds up over years of bad eating habits, smoking or uncontrollable factors. As plaque builds up, so does calcium. Thus, calcium is a measure of advancing disease. But paradoxically, many cardiologists today believe that calcium can wall off the fatty plaque and have a beneficial effect. Thus, there have been questions about whether a very high calcium score necessarily is indicative of high risk. Conversely, it has been unclear whether a calcium score of zero means essentially no risk of heart disease.

The latest study is quite clear on the second point. "The current results demonstrated that a coronary calcium score of zero does not routinely exclude risk of future coronary heart disease events," the authors write. In fact, seven of 75 people believed based on traditional risk factors to have a 21% or greater risk of heart attack in fact suffered one, or died of one, during the research, despite having a coronary calcium score of zero. So did seven of 195 people with zero calcium scores who were believed to be in the middle-risk range.