Coronary arteries aren't what they seem

12. November 2007 William Davis (5)
Why do stress tests so often fail to detect coronary atherosclerotic plaque? Why do even heart catheterizations--the "gold standard"--fail to disclose the full extent of plaque within the walls of coronary arteries?

We owe much of the explanation of these phenomena to Dr. Seymour Glagov, retired professor of pathology at the University of Chicago.



When studying the coronary arteries of people who died, he observed that people commonly had plenty of atherosclerotic plaque lining the artery wall, yet it did not necessarily impinge on the artery "lumen," or the internal path for blood to flow.

The only time the lumen became obstructed by plaque was when either 1) plaque grew to overwhelming levels and was severe and extensive, or 2) when a plaque had "ruptured," meaning its thin covering had been penetrated and eroded by the underlying plaque tissue like a volcano emerging from the surface and erupting.

This groundbreaking observation, now dubbed "the Glagov phenomenon," explains why someone can have a normal stress test on Tuesday but erupt a plaque on Wednesday.

The Glagov phenomenon also explains why heart scans can detect plaque when both stress tests and heart catheterizations fail to do so. Many physicians will then interpret this to mean that the heart scan was wrong. With the Glagov phenomenon in mind, you can see that the heart scan is not wrong, it is simply detecting coronary atherosclerotic plaque at a stage that is not yet detectable by the other methods.

In the illustration, you can see that the lumen of the vessel is maintained--despite the artery on the left having minimal plaque, the artery on the right containing moderate plaque. If either artery were examined by a test that relies on blood flow--stress test or heart catheterization--both would appear normal. But a test that examines the artery wall, such as a heart scan, would readily detect the artery on the right and probably even the artery on the left.




I am very grateful to Dr. Glagov and his insight into this important process. Otherwise, we might still be floundering around trying to understand the apparent discrepances between these tests that simply provide different perspectives on the same problem.
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Comments (5) -

  • Anonymous

    11/13/2007 1:04:00 AM |

    I saw a new small 2 pound ultrasound machine for detecting plaque in neck arteries just hit the market place.  Article was at: http://www.newstarget.com/022212.html

    It sounds exciting that something like this would be easily accessible - as the author speculates.  Do you think this new small devise will be helpful - if one has plaque in neck arteries does that typically also mean plaque in the heart?

  • Dr. Davis

    11/13/2007 2:54:00 AM |

    Actually, I purchased one of these devices about 7 years ago. The data is reasonably well worked out: carotid ultrasound for a measure called intima-media thickness is a reasonable second choice to coronary plaque measurement. It can be useful to augment information from direct coronary scoring, or when heart scanning is impossible, e.g, some people after bypass surgery.

  • Anonymous

    11/13/2007 7:11:00 PM |

    You've been concentrating a lot on coronary arteries, and the effect of plaque build up. What about the valves of the heart? Can plaque build up on, or otherwise affect them?

  • Dr. Davis

    11/13/2007 10:08:00 PM |

    This blog and the accompanying website, www.trackyourplaque.com, are intended to focus on coronary issues.

    However, I have been seeing aortic valve disease actually improve with vitamin D. Please see my blog post, Valve disease and vitamin D at http://heartscanblog.blogspot.com/search/label/Valve%20disease%20and%20vitamin%20D.

  • buy jeans

    11/3/2010 10:15:10 PM |

    When studying the coronary arteries of people who died, he observed that people commonly had plenty of atherosclerotic plaque lining the artery wall, yet it did not necessarily impinge on the artery "lumen," or the internal path for blood to flow.

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Track Your Plaque: Safer at any score

Track Your Plaque: Safer at any score

11. November 2009 William Davis (0)
Imagine two people.

Tom is a 50-year old man. Tom's initial heart scan score was 500--a concerning score that carries a 5% risk for heart attack per year.

Harry is also 50 years old. His heart scan score is 100--also a concerning score, but not to the same degree as Tom's much higher score.

Tom follows the Track Your Plaque program. He achieves the 60:60:60 lipid targets; chooses healthy foods, including elimination of wheat; takes fish oil at a therapeutic dose; increase his blood vitamin D level to 60-70 ng/ml, etc. One year later, Tom's heart scan score is 400, representing a 20% reduction from his starting score.

Harry, on the other hand, doesn't understand the implications of his score. Neither does his doctor. He's casually provided a prescription for a cholesterol drug by his doctor, a brief admonition to follow a low-fat diet, and little else. One year later, Harry's heart scan score is 200, a doubling (100% increase) of the original score.

At this point, we're left with Tom having a score of 400, Harry with a score of 200. That is, Tom has twice Harry's score, 200 points higher. Who's better off?

Tom with the score of 400 is better off. Even though he has a significantly higher score, Tom's plaque is regressing. Tom's plaque is therefore quiescent with active components being extracted, inflammation subsiding, the artery in a more relaxed state, etc.

Harry's plaque, in contrast, is active and growing: inflammatory cells are abundant and producing enzymes that degrade supportive tissue, constrictive factors are released that cause the artery to pinch partially closed, fatty materials accumulate and trigger a cascade of abnormal responses.

So it's not just the score--the quantity of atherosclerotic plaque present--but the state of activity of the plaque: Is it growing, is it being reduced? Is there escalating or subsiding inflammation? Is plaque filled with degradative enzymes or quiescent?

Following the Track Your Plaque program therefore leads us to the notion that it's not the score that's most important; the most important thing is what you're doing about it. We sometimes say that Track Your Plaque makes you safer at any score.
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