Is it possible to have blocked arteries but at the same time a low coronary calcium score?

The calcium score is a numerical value that’s associated with the likelihood of having soft plaque heart disease.

“A blocked artery means the narrowing in the artery is more than 70 percent narrowed, the point where blood flow is restricted,” says Dr. Larry Santora, MD, cardiologist, medical director of cardiac CT, and medical director of the Vascular and Wellness Center, Saint Joseph Hospital, Orange, CA, and author of “OC Cure for Heart Disease.”

Dr. Santora explains, “This is called ‘obstructive coronary artery disease.’ There is a direct relationship between total calcium score and ‘obstructive disease,’ so if the calcium score is greater than 100, the chance of an abnormal stress test is greater than 3 percent.

“If the score is greater than 400, the chance of an abnormal stress test is 15 percent, and so it goes”

A stress test can be done either with physical exercise or a chemical stress test.

“So you can have obstruction, though it is very unlikely, even with a very low score.

“However, if you are having angina, even with a very low score, then the chance of an abnormal stress test becomes dramatically higher.

“So anyone with symptoms of chest pain should have a stress test first, because you are then trying to determine if the chest pain is due to obstruction of blood flow in the coronary arteries.”

Can a person have a very high coronary calcium score, yet less than a 70 percent blockage in the arteries?

Dr. Santora explains, “The reason the score is high but the artery lumen (channel) is not severely narrowed is because the plaque is forming in the walls of the artery.”

Wouldn’t a CT angiogram (which measures the amount of unstable soft plaque) be preferable over a stress test?

After all, can not a stress exam miss severe coronary blockage? Wouldn’t the CT angiogram, which emits less radiation than a stress test, be more definitive?

“The CTA would be a helpful tool, but not preferable, since the CTA shows the shape of the artery (anatomy), but not the function or ‘flow’ in the artery,” says Dr. Santora.

Flow is also referred to as perfusion, which is why stress exams are usually called perfusion stress tests or myocardial perfusion tests.

Dr. Santora continues, “The stress test is a ‘functional test,’ whereas a CTA is an anatomic test. Sometimes, even with an invasive angiogram (which uses catheters), I find blockages that look borderline in narrowing, like 60 to 70 percent.

“Before putting in a stent, we place a wire through the narrowing and measure flow.

“It is called a functional flow reserve test (FFR). If the flow is not restricted, then I do not put in a stent.”

Dr. Santora’s areas of interest include interventional cardiology – coronary stenting, cardiac CT – CT angiography, and coronary calcium screening with EBCT.
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer.  


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