But for those in the middle, with a 10-year heart attack risk of 10 percent to 20 percent, learning that their arteries are clogged could change the course of medical treatment and perhaps foster changes in their habits. The factors considered in estimating risk are gender, age, cholesterol levels, smoking status and systolic blood pressure (the larger number) with and without treatment.
Each factor is assigned a point score. A 50-year-old man (6 points) who smokes (3 points) and has a total cholesterol of 200 to 239 milligrams per deciliter (3 points), an HDL level less than 40 (2 points) and a systolic blood pressure under 120 (no points) would rack up 14 points, giving him a 16 percent chance of a major cardiac event before he turns 60. (A woman at a comparable level of risk would have a point score of 21 or 22.) Based on currently available evidence, this man would be considered a good candidate for a CT scan.
For the motivated
But lowering his risk should entail more than medication to improve his cholesterol readings. He should also quit smoking, change his diet and start exercising to help raise his HDL, the "good" cholesterol that protects the heart. Without intensive intervention to foster such lifestyle changes, according to a well-designed study by Patrick O'Malley and colleagues at Walter Reed Army Medical Center, there was no change in risk level a year after CT screening. And even intensive intervention had minimal effect.
Since even a heart attack does not always stop people from smoking or overindulging, some experts say artery scans are likely to benefit only the most highly motivated.
Nathan Wong, an epidemiologist at the University of California, Irvine, who had previously observed beneficial changes in risk following CT scans, is now conducting a more scientifically designed study of how people respond to the findings of a scan.
In an interview, Wong explained that while the results of a CT coronary artery scan did predict a person's chances of a major cardiac event in the next 10 years, it was not yet known whether the value of screening exceeded that of other tests for heart disease. No randomized trials to assess the benefits of CT coronary scanning have been conducted. Such trials are the only way to know for sure.
Michae Lauer of the National Heart, Lung and Blood Institute noted in the September issue of The Cleveland Clinic Journal of Medicine that screening individuals for evidence of arterial disease would have far less of an effect on the incidence of heart disease - the nation's leading killer - than a population-based approach to reduce cardiac risk factors.
As for me, a rough calculation of my risk factors showed that I was not at "intermediate risk" for heart disease, and therefore not a good candidate for a CT scan. So I decided to go the statin route, encouraged by recent evidence that statins, or their effect on cholesterol, protect not only against heart disease but may also help prevent dementia. I'll have another cholesterol test in a month or so.
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