I remember reading years ago about the efficacy of calcium scans, so just looked up the current thinking. The American College of Cardiology has a good article: "Coronary Artery Calcium: Score? or No More?," May 20, 2014:
"Coronary calcium rules as a power player in assessing risk. "It's not a risk factor, it's the actual disease," said Robert O. Bonow, MD. "So, it's not surprising that it turns out to be a good predictor of events." For every calcified plaque found in a patient's coronaries, Dr. Bonow said there are many noncalcified plaques, too, such that the calcium burden measured by CAC probably equals about one-fifth of the total atherosclerosis burden.
And how many other tests can make this claim: there are no false positives with CAC scanning and very little measurement error.
In short, no matter which way you slice it, most agree that CAC offers the best discrimination of all the second-tier assessment techniques available—an opinion that is echoed in the recent guidelines. In several studies, CAC provided additional risk stratification when added to traditional risk scores, testing better than C-reactive protein (CRP) and carotid intima-media thickness (CIMT).
"It feels to me that we can say pretty definitively that if we were going to line up all the currently available risk markers that are not traditional risk factors, the winner is still CAC," said Dr. Greenland.
Another complaint lobbed against CAC is the lack of a randomized clinical trial showing that its use actually improves outcomes. Several groups, including one headed by Dr. Greenland, have tried to fill this gap, but the necessary trial would be both large and prohibitively expensive. "We tried to get a study like that funded but we estimated we'd need to enroll about 30,000 patients and it would cost between 80 and 100 million dollars to conduct," said Dr. Greenland. "In the current environment, that is unlikely to get funded."
The fact that numerous centers in the United States persist in offering cheap calcium scans without appropriate pre-screening has clearly damaged the test's reputation in the wider cardiology community.
"It's terrible medicine," Dr. Nissen flatly declared, especially when centers use billboard ads to pitch wives on a unique Valentine's Day gift for their husbands' hearts: Get his coronaries scanned for 99 bucks. Think of it as medicine's "blue light special." "It's a loss leader to get people into the cath lab in order to have unnecessary and inappropriate procedures," said Dr. Nissen—an opinion echoed by Dr. Greenland. Although these centers require, by law, a physician's referral, concerns persist that the referrals are rubber stamps and the scans are being massively overused.
Dr. Bonow suggests that cardiologists may be overstating the case. In the early days, CAC scans were being used "in some circles" to drive more cardiovascular imaging and more procedures, but this is not really the case anymore. "With time, I think the field has matured and we realize the value of this test when used properly," he said.
There are other tests as well. The CTA, as someone else mentioned in this thread.
The significant difference is the cost and ease to do.
“The calcium burden probably represents 1/5 of the total atherosclerosis burden”.
Calcified coronary lesions represent the cap over a atheroma that has become prominent. Calcified lesions are stable, in place, whereas vulnerable atheromas cannot be detected on the intimal wall except as provided by contrast agent in the cardiac catheterization lab, with high tech computerized calculation of the thickness of the intimal wall. The contrast agent shows the “available path” of oxygenated blood through coronary arteries, and the subsequent vulnerable coronary lesions which might break off in the presence of high LDL, VLDL (triglycerides) and specific subsets of Apolipoprotein A1 a marker protein of HDL. The importance of dyslipidemia in treatment cannot be ignored.
So, the value of being able to quantify calcified coronary lesions is as a % measurement (a quantifiable guess) of other unseen more vulnerable plaques and lesions which are the source of acute arterial blockage,by these lesions breaking off, traveling up, say, the carotid arteries to the brain, and causing ischemic strokes (brain damage from blocking oxygenated blood from reaching areas of the microvasculature of the brain. Ischemia.) as opposed to hemorrhagic strokes which are not this process.
Coronary ischemia that results from a plaque/lesion breaking loose in a coronary artery denies oxygen to the heart muscle... and kills heart tissue. Silent ischemia can be happening all the time, and the blood vessels genetically develop to grow around the blocked arteries to continue to supply, in many cases.
Not knocking Calcium score— but people should be aware that calcified lesions present a different risk of heart attack than the very many “vulnerable” “soft” lesions that result from build up of LDL underneath the intimal wall lining. And why it is still important to not provide high levels of LDL which migrate through into the intima and “loosen” the lesion containing built up cholesterol plaque.
Along with calcium score, folks should be concerned about the causality of this “vulnerable” lesion as being due to the actions of free radicals beginning a natural inflammatory response— from the body’s immune system providing chemicals in the blood to combat the inflammation. LDL has to be oxidized in order to migrate into a lesion. Anti-oxidants in the diet (vegetables, supplements, Vit C) can reduce the actions of free radicals and reduce the inflammation of the arterial lining wall, the intima.
By the way, the largest organ in the body is the intimal wall lining of all of the arteries, and micro arteries in the blood. Only a few cells thick, the intima, were it able to be spread out flat, would cover up to 3 tennis courts in surface area (like a car radiator— massive surfrace area compressed in folds of metal). The intima is a dynamic responsive tissue— if not inflamed. And it is the coronary arterial intima breaking down that is most noticeable. There is ischemic kidney disease— where the kidneys microvasculature is blocked and therefore kidney function is reduced (and causing blood pressure resistance the heart has to pump against).
Also, do not ignore sleep apnea— for it is the same as someone putting their hand over one’s mouth and stifling breath— while asleep. Gradual reduction over time of oxygen to the heart and brain— and damaging. Another example of silent ischemia.
It is a fascinating field, and very rewarding when patients can take care of themselves (barring very bad genetics as regards their lipid profile) and get better, and feel better and perhaps live longer. Sorry for the length of the post- but this is the single largest killer in America, men and women both. And a stroke is no way to live into one’s 60’s and 70’s. Knowledge is power- there are many good tracts which explain this process and how to slow it down at least.