Ask the Doctors September 2012 Issue

Ask The Doctors: September 2012

My brother had an electrocardiogram and his doctor said it showed a “silent heart attack.” We’re in our late 60s, and have similar health histories. We take drugs for high blood pressure and high cholesterol. Am I also at risk for a silent heart attack? I have occasional chest pains, but nothing serious.

Although silent heart attacks are unusual, they happen in enough people (including your brother) to make them worth talking about. When a coronary artery becomes blocked and heart muscle is injured during a myocardial infarction (MI), most individuals have striking symptoms, such as chest discomfort, indigestion, nausea, or shortness of breath. However, there are a few people who do not feel anything. This may have something to do with the pattern of nerves emanating from the heart, which differs between individuals. In other words, we are all “wired” differently. Also, not everyone’s cardiac nerves function equally. For example, people with diabetes are more likely to have silent heart attacks because their medical condition tends to injure nerves.

Another factor which can affect symptoms with heart attacks is how fast the heart compensates, by sending blood flow to the muscle tissue from other vessels. People with robust “collateral vessels” coming from other parts of the heart may not experience as severe symptoms as those who do not.

Another important fact is that, while an electrocardiogram (ECG) is an inexpensive, easy-to-perform test, its results are not 100 percent accurate. For example, an ECG can suggest the presence of an old heart attack, but not be correct. This is a situation known as a “false-positive result.” In order to determine if someone has truly experienced a silent MI, a stress test such as a nuclear imaging study or a heart catheterization are needed. In your case, the chest pains do not seem particularly worrisome. However, given your age, risk factors for heart disease, and brother with a possible silent MI, you might benefit from the types of testing listed above.

This may be a silly question, but can statins, exercise and a healthy lifestyle actually reverse plaque buildup in your arteries, or is it always there, and the best you can hope for is to not get more?

Your question is extremely reasonable–in fact, cardiologists have been investigating it for more than 30 years! The process of coronary artery disease (CAD) starts with a so-called “fatty streak,” a thin deposit of cholesterol on the artery wall which can occur in adolescence or young adulthood. Depending upon genetics, diet, smoking, and other factors, the fatty streak can progress to become a “soft plaque,” which is a cholesterol-laden deposit in the vessel wall. 

The body will try to eliminate the soft plaque by sending in white blood cells, which you can think of as the “clean-up crew.” The problem is, these cells often consume a large amount of cholesterol, then burst, dispersing the cholesterol further. Other white blood cells are attracted by all of this activity, and the enyzmes they secrete can weaken the wall of the soft plaque, making it vulnerable to rupture. Rupture of a vulnerable plaque is the key factor in starting a heart attack, or acute myocardial infarction (MI).

Soft plaques often mature and harden, as calcium deposits in them. These plaques are less likely to rupture, but can still block blood flow. The keys to treatment of CAD are threefold: to keep plaques from forming, getting larger, or rupturing, and in so doing, to prevent MI. Studies of people’s coronary arteries have shown that intensive medical therapy with statins and other drugs, coupled with a healthy lifestyle, can prevent plaque enlargement, rupture, and subsequent heart attacks. Heart-healthy living by itself is probably not enough, if CAD is already present. In that case, aggressive medical therapy is absolutely needed to prevent worsening symptomatic heart disease. As to your question, the plaques will sometimes shrink, but this can generally only occur with statin therapy, and when the plaques are still soft, and noncalcified.