My friend Seth wrote:
A few months ago, because of this blog, I got a free heart scan from HeartScan in Walnut Creek. It’s a multi-level X-ray of your heart and is scored to indicate your heart disease risk. . . . What’s impressive about these scans is three-fold:
1. The derived scores are strongly correlated with risk of heart disease death. . . . Here is an example of the predictive power. . . .
2. You can improve the score. Via lifestyle changes.
3. The scans provided by HeartScan are low enough in radiation that they can be repeated every year, which is crucial if you want to measure improvement. In contrast, a higher-tech type of scan (64 slice) is so high in radiation that it can’t be safely repeated. . . .
Heart scans, like the sort of self-experimentation I’ve done, is a way to wrest control of your health away from the medical establishment. No matter what your doctor says, no matter what anyone says, you can do whatever you want to try to improve your score. . . .
This looked pretty good. Heart attacks are the #1 killer, maybe I should be getting a heart scan. On the other hand, Seth’s references are to a journal article from 2000 and a news article from Life Extension magazine, hardly a trustworthy source. So I didn’t know what to think.
I contacted another friend who works in medical statistics, who wrote:
I don’t know any of this literature but the fact that his source publication dates back to 2000 while the screening method has clearly not gained widespread traction is an indicator that the cost/benefit ratio is not very favorable (though it’s no doubt very favorable to HeartScan who make money out of doing the scanning).
I found this more recent (though skimpy) review, “CT-Based Calcium Scoring to Screen for Coronary Artery Disease: Why Aren’t We There Yet?” which casts doubt on the whole idea (and given that it’s written by radiologists it has some credibility because they would normally be the first to promote a radiology-based screening technique). There were also some links to reviews of the potential dangers (carcinogenic) of repeated CT scans.
From this information, I wouldn’t try to talk Seth out of getting heart scans, but I won’t rush out to get one of my own.
Points 1 & 2 together do not imply that lifestyle changes that improve your score will also reduce your risk of heart disease.
you might like playing around with this;
http://www.mesa-nhlbi.org/CACReference.aspx
– the papers mentioned include more up to date references, from reputable sources.
The statement that scans have not gained "widespread traction" is a bit wide of the mark – CAC is used clinically.
The argument that the test's failure to gain widespread traction indicates that the cost/benefit ratio is not very favorable would be more persuasive if health care were purchased in something closer to a free market.
"…maybe I should be getting a heart scan."
…or maybe you should just do the lifestyle interventions no matter what the heart scan shows because they have multiple health benefits independent of the scan results.
…or maybe you should calculate your pre-scan probablility of developing coronary artery disease in the next using traditional risk factors (age,gender, blood pressue, cholesterol) with the Framingham Risk calculator and then calculate how the results of the scan change your risk of developing symptomatic coronary disease over the next 10 years (i.e. a Bayesian analysis. ) Then decide if the money you would spend on the scan could be better spent elsewhere.