Features August 2017 Issue

Heart Disease Is More Than “Clogged Pipes”—It’s a Disease of Inflammation

Arteries lined with plaque pose a heart attack risk. But you shouldn’t ignore the body’s inflammatory response to cholesterol plaque deposited inside your arterial walls.

It’s easy to think of heart disease as a “plumbing problem.” Arteries, like household pipes, can become clogged. And like a clogged pipe that won’t let much water through, a blocked artery can reduce blood flow. This leads to angina, the chest pain that results from a decrease in oxygenated blood reaching the heart muscle. Completely blocked arteries also can lead to heart attacks.

But the widely used plumbing analogy overlooks an important and dangerous aspect of heart health: the plaque that lies within the artery walls. Cholesterol, fats and other materials get deposited in the walls of your coronary arteries. These deposits may have little impact on blood flow, but they are especially vulnerable to rupturing. And when that rupture occurs, platelets in your blood rush to the site, and a blood clot can form.

So it’s not the cholesterol itself that is the problem, but the body’s inflammatory response to it, explains Michael Rothberg, MD, of Cleveland Clinic. “Inflammation in the wall of an artery can eventually cause it to rupture, triggering a blood clot at the site and leading to a heart attack,” he adds. “Thus, the problem isn’t the narrowing of the artery per se, but the process that is taking place inside the artery wall. It can’t be fixed with a mechanical procedure like a stent, because it isn’t a mechanical problem.

© Guniita | Dreamstime.com

Top illustration: Healthy heart and artery. Bottom illustration: Ruptured plaque leading to formation of blood clot and heart damage.

Inflammation Info

Inflammation in the walls of the arteries is similar to inflammation that occurs with an infection, Dr. Rothberg says. The job of the body is to keep out foreign invaders and neutralize threats that get past our outer defenses. To do that, it may create some local destruction, like collateral damage in wartime. “In this case, the body sees the LDL cholesterol in the artery wall as something that should not be there,” he says. “Cells from the immune system respond as they would to a virus or other invader by engulfing the LDL and secreting chemical signals to attract more immune cells. This creates a plaque in the wall of the artery. If the inflammation goes on long enough, the plaque can rupture, leading to a heart attack.”

Controlling Inflammation

There are a number of steps that you can take to reduce inflammation and lower your risk of a heart attack. They include the well-established rules of heart disease prevention.

“For a long time we have known that heart disease is related to smoking, diet, sedentary lifestyle, high cholesterol levels, high blood pressure and stress,” Dr. Rothberg says. “All of these lead to inflammation. To reduce it, people can stop smoking and make sure they eat a healthy diet with lots of fruits, vegetables, and whole grains, while avoiding processed foods and sugar. They should make exercise a regular part of their lives. They should take steps to reduce stress, such as mindfulness meditation. Some medications that reduce cholesterol, statins in particular, also reduce inflammation, as does a daily aspirin. Both of these medications should be taken only at the advice of a physician.”

He adds that every attempt to control blood pressure should be made. It usually requires a combination of diet, exercise and stress reduction, but may also require medication. Many people with high blood pressure need more than one medication to reach their goals.

Knowing Your Risk

Detecting vulnerable plaque hidden in your artery walls has been a difficult task. But advancements in an imaging technique called intravascular ultrasound (IVUS) are making it easier for doctors to better assess how much plaque is just under the surface of an artery’s inner lining. IVUS uses a catheter that emits sound waves in the suspected artery to create an image of the arterial wall.

But imaging isn’t the only way to gauge your risk of a heart attack. Dr. Rotherberg suggests using an online risk estimator operated by the American College of Cardiology: http://tools.acc.org/ascvd-risk-estimator/.

“Controlling risk factors is the best way to control heart disease,” Dr. Rothberg says. “If the risk factors go away, so will the inflammation.”

You can also have levels of ultra-sensitive C-reactive protein (us-CRP) in your blood tested. It’s a marker of general inflammation. Dr. Rothberg says knowing your us-CRP levels can give you a better idea of your heart disease risk when you also consider other cardiac risk factors, such as cholesterol and blood glucose levels, blood pressure, family history, obesity, smoking, and a sedentary or active lifestyle. “However, having a normal us-CRP does not mean you have no local inflammation or that you don’t have to worry about having a heart attack,” he adds.

© Guniita | Dreamstime.com

Stable plaque (left) in your arteries has a thick fibrous cap over a fatty core. Unstable plaque (middle) has a thinner cap that is more vulnerable to rupture and blood clot formation (right).

When the Pipes Need Clearing

Of course, heart attack risk isn’t the only concern when it comes to plaque in your arteries. Arteries narrowed by plaque buildup can restrict blood flow to the heart muscle. The pain that follows is called angina. When it occurs after exertion and hard work by the heart, it’s known as stable angina. Unstable angina is that same type of chest pain, but discomfort that comes on at rest or any time at all.

“There are several approaches to improving these symptoms,” Dr. Rothberg says. “First, there are medications, such as nitroglycerine, which can relieve the pain. There are other medicines, such as beta-blockers and calcium channel blockers, which lower the demand from the heart and prevent the pain. Another way to improve symptoms is with a supervised exercise program.  In fact, exercise is probably the best means of improving angina because it stimulates collateral flow—other arteries can expand to accommodate more blood flow to the affected area.”

In cases where medications and lifestyle don’t improve symptoms and circulation, revascularization with a stent can open the narrowed area and improve blood flow. “It is important to understand that this will not reduce the chance of a heart attack,” Dr. Rothberg says. For some patients, symptom improvement is temporary after receving a stent. 

“In contrast, in the setting of an acute heart attack, when the artery is completely blocked by a clot, angioplasty to open the artery and placement of a stent can be life-saving,” Dr. Rothberg explains. However, stenting to relieve angina and stenting to open a blocked artery during a heart attack have two different goals.

Work with Your Doctor

Dr. Rothberg describes heart disease as a “biological process,” not a mechanical one.

“Treatment requires a biological approach,” he says. “Some of the most effective treatments are targeted at lifestyle, such as smoking, diet and exercise. Medications can also be lifesaving, and patients need to take their medications. It is also important to remember that heart disease cannot be ‘fixed’ by placing a stent.”

You can’t go back to a sedentary lifestyle, eat a poor diet, and not take your medications as prescribed. That’s a prescription for worsening heart disease, not a longer, healthier life.

“Patients should ask their doctors about what they can do to lower their risk of heart disease, including finding the right diet, and managing hypertension and cholesterol,” Dr. Rothberg says. “If they already have angina, they can ask about anti-anginal medications and supervised exercise.  For patients who already have heart disease, treatment with lifestyle and medications is the most important way to reduce risk of a heart attack and death.”

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