Heart attacks are not caused by plaques making arteries too narrow. They are caused by plaques suddenly breaking off from the inner lining of a heart artery, followed by bleeding, and then a clot forms that completely blocks all blood flow to a part of the heart muscle. The part of the heart muscle that is suddenly and completely deprived of oxygen then dies, which is a heart attack.

You can help to prevent heart attacks by eating a heart-healthy anti-inflammatory diet and exercising, and your doctor may prescribe statin drugs. Exercise helps to prevent heart attacks by making plaques more stable so they do not break off as easily (BMJ Open Sport & Exercise Medicine, 2018;4 (1):e000370). A new study shows that statin drugs are associated with increased amounts of calcium in heart arteries that stabilize plaques so they are less likely to break off (JAMA Cardiology, August 18, 2021).

How Doctors Measure Plaque Stability
Having plaques in arteries increases risk for a heart attacks and all plaques have some calcium in them. A CT scan can show how stable plaques are (American Journal of Roentgenology, March 2015;204(3):W249-W260). X rays and sonograms can also show the difference between stable plaques that are not as dangerous and those that are unstable and more likely to break off to cause heart attacks. Stable plaques contain more calcium and are smoother and more homogeneous than unstable plaques. The radiologist estimates plaque stability by looking for an extensive calcification cap on the outside of the plaque, less lipid-rich areas inside the plaque, increased fibrous areas and less structural change. See Exercisers Have More Stable Plaques

A regular X ray or calcium scan can tell if your plaques are likely to break off to cause a heart attack (J Thorac Dis, Apr 2018;10(4):2365–2376). If the plaque is loaded with calcium on its outer border and is low in fat, it is likely to be a stable plaque and the person is not at high risk for a heart attack. On the other hand, if the plaque is full of fat and has very little calcium, it is an unstable plaque and the person is at significant risk for a heart attack.

How a Pro-Inflammatory Diet Forms Plaques
Exercise and statins may both help to prevent heart attacks by stabilizing the plaques in your arteries, but neither exercise nor statins prevent plaques from forming in arteries. Plaques are formed primarily because of inflammation, which is linked to the pro-inflammatory foods you eat.

Your immune system is good for you because it helps to protect you from infections. When a germ gets into your body, your immune system makes cells and proteins that attack and kill germs. When the germs are gone, your immune system is supposed to dampen down. However, if your immune system stays active all the time, it can use the same cells and chemicals to attack the inner linings of your arteries and increase your risk for a heart attack. This is called inflammation. Your immune system punches holes in the inner linings of your arteries and causes bleeding and clots. Plaques form at the site of the clots and start to cover the inner linings of arteries. We know that cholesterol isn’t the primary cause of forming plaques because cholesterol does not start to show up in plaques until long after the holes, bleeding and clotting have occurred on the inner linings of arteries.

Different types of bacteria that live in your colon turn your immune system on and off. What you eat determines which types of bacteria grow in your colon because these bacteria eat the same food that you do. These colon bacteria influence how quickly you form plaques in your arteries. Foods favored by the bacteria that turn on your immune system are classified as pro-inflammatory and increase risk for forming plaques in your arteries to increase risk for heart attacks (Front Pharmacol, Sept 25, 2018;9:1082). Anti-inflammatory foods are favored by types of bacteria that help to prevent plaques from forming and decrease heart attack risk. A diet that is high in anti-inflammatory foods such as fruits, vegetables, whole grains, legumes and nuts is associated with reduced risk for cardiovascular disease, while pro-inflammatory foods such as sweets, refined grains, juices, meat from mammals and processed meats are associated with plaque formation and increased risk for a heart attack (J Amer Coll Cardiology, July 2017;70(4)).

Coronary Artery Calcium Score Tests Can Be Deceptive
Doctors use a test called “Coronary Artery Calcium Score” to measure the size of plaques in arteries leading to the heart, but this test repeatedly finds that endurance athletes have the highest calcium scores among healthy people, even when they are at very low risk for heart attacks (European Heart Journal, July 21, 2021;42(28):2737–2744), and their doctors may incorrectly tell them that they are at high risk (Circulation, 2017;136:149–151). All older endurance athletes who have high “Coronary Artery Calcium Scores” need other tests to assess the stability of their plaques and their risk for suffering a heart attack (JAMA Cardiology, August 18, 2021).

My Recommendations
• To help prevent or reduce plaque formation, follow a heart-attack-preventing diet that is high in anti-inflammatory foods and low in pro-inflammatory foods. This means that you should eat plenty of plants and restrict red meat, processed meats, sugar-added foods, all sugared drinks and fried foods.
• Avoid being overweight
• Do not smoke
• Limit or avoid alcohol
• To stabilize existing plaques and widen your coronary arteries, try to exercise every day for at least half an hour a day. Exercising more than that may be even more protective. Your doctor may also prescribe statins, but statins do not replace a healthful diet and exercise.
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