Say coronary artery disease in a crowded room and very soon the conversation will turn to surgery and stents: who got one, who needed one and the inevitable, who was perfectly fine until it was found that one of these procedures was necessary. You may wonder how things could get so bad that you need an operation without realizing that there is any problem and how the decision to recommend a stent or bypass surgery comes about.
Does every narrowed spot in the coronary arteries have to be treated to prevent a heart attack?
The answer has changed quite a bit over the past 40 years because the understanding of coronary artery disease has changed. At the dawn of the 20th Century, coronary artery disease was thought to be a gradual encrustation of arteries that choked off heart muscle, much like the corrosion of the pipes in your home. The treatment seemed obvious. When the narrowing gets bad, clean it out or go around the problem. Deliver blood where it is needed and heart attack will be prevented.
It took about 50 years for bypass surgery to come to fruition and it worked. The operation was a grand success. People who had the surgery were relieved of the symptoms of coronary artery disease. Some of them even lived longer than they might have otherwise. However, the surgery was not very effective in preventing heart attacks. With a little more observation came the irony. Even though the operation became a very important part of the treatment of coronary artery disease, the idea that drove the development of the procedure was not completely accurate.
It’s not always the devil you know…
For many years and even most of the time today, coronary artery disease was discovered because it caused symptoms. It made someone short of breath during usual activities or it created chest discomfort with movement or anxiety. In any case, a narrowed artery brought the disease to recognition and a narrowed artery was what everyone thought needed to be addressed.
What we know today about Atherosclerosis is that the disease that gets into the walls of your arteries is substantially different from the corrosion of your plumbing. The first difference (or maybe it’s a similarity) is that if the disease is at one place, it is almost certainly everywhere else as well. Where one narrowing is discovered, there are ten other places in the artery that have disease as well, but are not narrowed. Atherosclerosis rots the walls of arteries from within, simmering for some time before obstructing the channel for blood flow. Therefore, where a narrowing of an artery is discovered is just the tip of the iceberg, quite literally.
The second and most important difference is that any site in the arteries where disease is present can become very inflamed and make blood clot. This means that arteries may become narrowed or closed in an instant, anywhere. The spot in an artery likely to cause a heart attack may be the narrowed spot that is visible or, more often, some other diseased site with no visible narrowing at all before the blood clot forms. This is the reason that bypass surgery was not a very effective protection from heart attack for most people.
This does not mean that bypass surgery and stents are not useful. It just means that, under most circumstances, surgery and stents are not used to prevent heart attack. About 1/3 of people with chest discomfort due to coronary artery disease are unhappy with symptom control. Despite the use of medicines, chest discomfort prevents normal daily activities, rising and grooming in the morning or even taking a short walk. Facing such limitations, the choice to have a procedure performed is driven by the wish to resolve symptoms.
The hobbled heart
Heart muscle that is repeatedly shorted in its energy supply weakens and participates less in every heartbeat. Over time and with more than one artery narrowed, large segments of heart muscle may weaken substantially, hobbling the heart’s ability to pump blood. There are many people who have more than one narrowed artery by the time that their problem is first recognized. Months, or maybe years of little physical activity allow the disease to silently tighten its noose. When the heart is rarely asked to work hard, it will hardly warn of its jeopardy. The danger of disease that has reached this point is that a bleeding ulcer, a case of the flu, an angry gall bladder or worse, a tiny heart attack that might have been survived will all prove much more difficult to face than would have been the case with a heart that could pump normally.
A heart that is hobbled can be recognized, even when chest discomfort does not warn of a problem. This is the basis for the exercise tolerance test (ETT). Sometimes referred to in error as an exercise treadmill test, measurement of physical fitness can be performed with a treadmill, bicycle or virtually any type of exercise. The goal is to uncover hidden limitation that may be due to heart disease. Alternatively, there are several methods used by physicians to measure the heart muscle’s strength. When physical fitness and/or the strength of the heart muscle are abnormal, the next heart attack or other major illness will be trouble.
Restoring normal blood flow to heart muscle may allow it to recover. That means that any future illness may be faced with a heart that is more capable of doing its job and the next heart attack might just be survivable. Stress tests and measurements of the heart’s strength are the tools used to identify the hobbled heart that may improve with a repair of its arteries. This does not mean that every person with limited exercise capacity or abnormal heart strength needs surgery. No two people with severe coronary artery disease face exactly the same challenges or have exactly the same wants, needs or concerns. Therefore, the most important aid for the decision to undergo stent or bypass surgery under these circumstances is the advice of a trusted physician.
Unstable: The devil you know.
There is one setting where a specific site in an artery can be recognized as the potential source of a heart attack. That setting is unstable disease. When an angry artery causes blood to clot, the blood clot takes a life of its own. It may grow rapidly and close the artery. The result is a heart attack. Just as often, the blood clot grows rapidly, but only to the point that it narrows the artery severely and stops there. Heart muscle may not suffer severe damage. Instead, the result is symptoms that get increasingly worse, often to the point that they will appear with little or no effort. The problem with a blood clot is that it is completely unpredictable. Having narrowed the artery and come to the precipice of a heart attack, the blood clot may stop and heal. On the other hand, it may not. If the decision is not, then anytime from the first change in symptoms until about two months later, the clot may grow again and fulfill its capacity to cause that heart attack.
Someone with symptoms that have just appeared for the first time, or that occur at rest or are worsening may have a blood clot that ceased its growth for a time. Symptoms like this are called “unstable” because they may represent the unstable behavior of a blood clot. Within thirty days of the onset of unstable symptoms, the chance of a major problem or damage to the heart is about one in three.
Medication can usually calm a blood clot and stop its growth. However, when symptoms persist or there are other signs of potential danger, the artery may have to be treated with a stent or bypass surgery. Under these very specific circumstances, treating the narrowed site in an artery to improve blood delivery can, in fact, prevent a heart attack.
The abbreviated version is: When symptoms are unstable, call your physician. The narrowing responsible for symptoms may need treatment. He or she may want to perform testing to assist in that decision. When no symptoms are present, or when symptoms have been the same for quite some time, any narrowing that is present is already healed. The decision to have treatment beyond medication depends upon the outcome of testing that your physician has requested and your discussion with him or her about control of symptoms.
The essential treatments for coronary artery disease and heart attack are to maintain our body’s inner environment near design conditions with a controlled diet, regular physical activity, weight management and carefully chosen medications. The most basic aspect of that treatment, the part that applies to everyone, is to follow a healthy lifestyle.
Surgical bypass and stent-assisted angioplasty of severely narrowed arteries are extremely important tools to restore normal blood flow to heart muscle. Either can be used to relieve changing or unstable symptoms and potentially derail a heart attack in evolution. In someone who has stable symptoms, or none at all, invasive treatments are needed only if symptoms are unmanageable with medication or when disease is crippling the heart’s ability to perform.