There is another indirect assessment of vitamin K2 activity that gets straight to the heart of the Calcium Paradox. Coronary artery calcium scoring is a specialized type of ultra-fast X-ray imaging that measures the presence and amount of calcium buildup in the arteries that supply blood and oxygen to your heart. If your main goal of K2 supplementation is reducing your risk of heart attack, this is an important test to take, to measure that risk.
Coronary artery calcium (CAC) scoring, also called calcium score or heart scan, is a technique that uses computed tomography (CT) scanning technology to quantify the volume and density of calcium in each of your coronary arteries. The calcium presence is calculated to give you a “score” or number that represents your arterial calcium burden. Remember that arterial calcification is an active process mediated by bone-building cells. That causes calcium to accumulate within plaque in a consistent ratio, occupying about 20 percent of plaque volume. For that reason, the amount of arterial calcium detected with a heart scan reflects the buildup of atherosclerotic plaque.
Vitamin K2 deficiency isn't the only factor contributing to heart disease, but undercarboxylated MGP (matrix gla protein) levels, a sure sign of K2
deficiency, do correlate to the severity of arterial calcification and the CAC score.7 The greater the degree of K2 deficiency, the higher the calcium score.
A high CAC score on electron beam computed tomography—a precise type of CT, discussed further below—is a better predictor of mortality than is age.8 That means you are only as old as your arteries. For example, if you are a 60-year-old man with a low CAC score, there's a good chance you'll live to a ripe old age. On the flipside, if you are a 45-year-old man with a heavy calcium plaque burden, you are more likely to be one of the unfortunate souls who suffer a massive heart attack at age 50—if you don't take action to prevent it.
Sudden death from heart attack is much more highly correlated with arterial calcification than with cholesterol.9
The big advantage of CAC scoring is that it quantifies your risk of heart attack. A low score means low risk, a high score means a high risk. No other risk factor offers that kind of graded risk assessment. The significance of your CAC score will depend on the scoring system used by the center that does your scan. The most widely used scoring system is Agatston scoring. Below is a typical reference table for interpreting CAC scores using Agatston scoring.
You can't get an accurate heart scan using any old CT device. Most hospital scanners that are fine for imaging stationary organs, like the brain, are not fast
enough to image the beating heart. The heart appears as a blur on standard CT scans, making it impossible to precisely quantify calcium burden. A heart scanner is a precision instrument that uses electron beam computed tomography (EBT) or the even faster, more recent multi-detector CT (MDCT).
A coronary calcium scan takes about 10 to 15 minutes in total, though the actual scanning takes only a few seconds. The CT scanner is a large machine with a hollow, circular tunnel in the center. You lie on your back on a table that slides into the tunnel. If you feel anxious in enclosed spaces, you may need to take medicine to stay calm, but this isn't a problem for most people because your head remains outside the opening in the machine. During the test, the scanner makes clicking and whirring sounds as it takes pictures. It causes no discomfort, but the exam room may be chilly to keep the machine working properly.
Imaging centers offering heart scans are popping up across Canada. Your provincial health care plan may cover part of the test fee, but you will have to pay out of pocket for the rest, which may be as much as $2,000. If you live a reasonable driving distance from the border, you are probably close to an American imaging center that offers the latest heart-scanning technology for as little as US$300. Do your homework and make sure the center you choose is using EBT or MDCT technology for heart scans. You can't just show up, either; you need a doctor's referral. Many centers have online referral and requisition forms that you can print and bring to your doctor. Test results will be sent to your physician and you might leave with a copy in hand, as well.
CAC scoring is not a crystal ball. Although it can tell you how much atherosclerotic plaque is clogging your arteries, it can't tell you the location of that plaque or how severe a blockage is at any particular point. Where CAC scoring really shines is in pinpointing the risk of a cardiac event among the large group of people classified as intermediate risk according to traditional guidelines. The advantage to patients and physicians is that a CAC score can improve the accuracy of predicted risk among the patients in whom clinical decision making is most uncertain, the medium-risk people with no apparent symptoms.10
For example, if you're an overweight male smoker with high cholesterol and a family history of heart disease, there's a high chance that you will eventually become a heart attack victim, and your CAC score probably won't tell you anything you haven't already been ignoring. Similarly, if you are a nonsmoking, healthy weight, premenopausal female, it's unlikely you will
suffer a heart attack in the foreseeable future and unlikely that you will have a surprisingly elevated CAC score. But what if you are a fit 45-year-old male with normal cholesterol and an extensive family history of heart disease? Or a postmenopausal woman with slightly elevated cholesterol? The addition of CAC scoring to the conventional prediction model based on traditional risk factors (listed below) significantly improves the classification of risk. It moves most people out of the gray zone and into a black or white category.11 Fifty to 75 percent of intermediate-risk patients are reclassified by CAC into more accurate heart attack risk categories, leaving fewer patients in the truly
“maybe, maybe-not” category.12 Risk Factors for Heart Disease
overweight
high blood pressure
LDL cholesterol level above 2.6 mmol/L (millimoles per liter) HDL cholesterol level below 1.0 mmol/L
cigarette smoking male over 45
female 55 or postmenopausal diabetes or prediabetes
family history of coronary heart disease
How will boosting your K2 intake affect your calcium score? Vitamin K2 deficiency, as measured by undercarboxylated MGP, increases arterial calcification and CAC scores. In animal studies, K2 supplementation dramatically reduces arterial calcium burden in only six weeks. Human clinical trials got underway in 2011, and we can anticipate preliminary results within a year or two.
Should You Be Tested?
Since the real value of CAC scoring lies in discerning the likelihood of heart attack among individuals without symptoms and without major heart disease risk factors, determining exactly who should get the test is very difficult.
CAC scans are too expensive to recommend broad, unselected screening, though that practice carries the best chance of identifying heart disease that might otherwise be missed. Based on the fact that calcium plaque tends to creep up sometime after the age of 40 for men and 50 for women, age is the only guideline currently in use at most testing centers. How age should be combined with other risk factors remains unsettled. If you are in the age
bracket in question, concerned about your heart attack risk and can afford the test, then go for it.
It's easier to say who should not have a heart scan. In the Western world, nearly everyone over the age of 20 has some plaque buildup. CAC scoring in people with low heart disease risk mostly leads to needless expense and anxiety. If you are a man younger than 40 or a woman younger than 50 with normal blood pressure, normal cholesterol and healthy body weight and you don't smoke, it's unlikely that the calcium plaque you probably have in your arteries is life threatening.
For an in-depth look at coronary artery calcium scoring, check out Track Your Plaque, 2nd edition (2011, iUniverse), by cardiologist William Davis.
The book explains the ins and outs of measuring coronary plaque and provides a three-step plan to identify and treat the causes of your plaque.
Although the first edition of the book predates the awareness of K2, the updated (and online) protocol includes this critical artery-clearing vitamin.