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Hidden Epidemic: Heart Disease in America
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Watching: The Hidden Epidemic - Heart Disease In America

Chapter 9: Root Causes Revealed [5:26]

The systematic nature of the disease becomes clear, and with it, the role of the immune system in causing heart attacks.

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Transcript: Chapter 9 - Root Causes Revealed

The systematic nature of the disease becomes clear, and with it, the role of the immune system in causing heart attacks.

NARRATOR: All plaques start with too much LDL—the bad cholesterol—accumulating in the blood. Libby's research focused on the particular makeup of the plaques in the artery walls..

DR. PETER LIBBY: Just a few years ago, most regarded the atherosclerotic plaque as an accumulation of waxy debris on the wall of the artery. What we have appreciated more and more is that the atherosclerotic plaque itself is filled with cells that are busily at work exchanging messages.

NARRATOR: The plaques send messages that spark the immune system into action. Sensing there are foreign invaders in the artery walls, the body does what it would do with any other infection or irritation. It responds with a cascade of chemical reactions that create inflammation at the site of the plaque. White blood cells come and try to help heal the inflamed site. Anywhere else in the body, this would be a normal, healthy reaction. But in the heart, once the white blood cells arrive, they're trapped in the plaque and can't do their job. Instead they trigger even more massive inflammation.

DR. PETER LIBBY: The same warriors that we use to fight off invaders are turned against us and become, indeed, the disease itself.

NARRATOR: Over tine, the inflamed plaque grows, and pushes the wall of the artery ouward. The center of the artery stays clear for normal passage of blood, but at any point the plaque in the wall can become unstable with disastrous results.

DR. STEVE NISSEN: For a variety of reasons, that plaque gets a fracture. It can even be just a little micro-tear. And when the, when the plaque tears or fractures, then the tissue is exposed to flowing blood and it causes a blood clot to form.

DR. PETER LIBBY: So when we have a popped plaque, we set the stage for a sudden blood clot, and that is all too often the root of a heart attack, a stroke, or sudden cardiac death.

NARRATOR: The biggest surprise was that ruptured plaques—not clogged arteries—turned out to be the cause of 70% of all heart attacks. This was a totally new way of thinking about heart disease not as a localized problem of clogged pipes, but as a systematic disease which affects the entire heart.

DR. STEVE NISSEN: And we began to realize why we were struggling with this disease. By the time you see that first narrowing in the artery, the disease is everywhere.

NARRATOR: This was the answer they'd been looking for. If the disease was everywhere in the heart, it explained why patients kept coming back with repeat heart attacks or other problems after they'd been treated.

DR. STEVE NISSEN: You can bypass the arteries, but if you don't stop the disease that's causing the plaque to build up, those bypasses plug up, too. You can put a stent in the artery at one location. But then a narrowing occurs at another location.

DR. STEVE NISSEN: And we're beginning to understand better how inflammation is triggered in the body, and how it's triggered in the coronary arteries.

NARRATOR: The new challenge was to find a way to measure inflammation and then see if it could be treated.

DR. STEVE NISSEN: We learned that there's a very good measure, a blood test that can measure the level of inflammation in the body known as C-reactive protein, or CRP, the higher your CRP, the more likely you are to have a heart attack or a stroke. Now there's a surprise here. The drugs that we use to lower CRP are the very same statin drugs that we use to lower cholesterol. It was a bonus that we didn't understand when the statin drugs were developing. We thought they were just lowering cholesterol. What we were able to show, that the more you lowered CRP, the more you reduced inflammation the lower the risk of death, heart attack, and stroke.

NARRATOR: From the development of intravascular ultrasound to the new understanding of inflammation in the heat, the stage is now set for a fundamental change in the way heart disease is diagnosed and treated.

DR. PETER LIBBY: We have transitioned from being plumbers, if you will, to becoming much better biologists, and I think that that opens up a wonderful window on the future in terms of what we're going to be able to offer the population in terms of prevention and care.

DR. STEVE NISSEN: And I think this has great potential to finally turn the corner and begin reducing death rates from this disease, something we've been working for decades to try to achieve.

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