Ask the Pharmacist

Q) I had to do an electrocardiogram (ECG) at my pre-op prior to some routine surgery. When I got the results back, I was told that at some point in my past I must have had a heart attack. How could I have had one without being aware of it?

A) While this probably sounds like a strange and rare phenomenon, it is not at all uncommon for heart attacks to go unnoticed for many years. Heart attacks of this nature are called silent heart attacks or silent myocardial infarctions (SMI) and one study estimated that they represent 45% of all heart attacks that occur annually (other studies suggest the figure is closer to one in five).

There is also a misperception out there that a silent heart attack must be “better” than a recognized one. However statistics show that people who are “healthy” but have been diagnosed with a silent heart attack seem to slightly fare less well over the long term than those people who suffered a classic type of heart attack and were therefore treated promptly.

The theory behind this finding is that a recognized heart attack acts as a wake-up call for many of us. As such we start eating better, exercising more often and begin taking medications that reduce our risk of having a second one. Obviously no such interventions occur in the silent group as they are unaware of what’s gone on inside their bodies.

So why are some heart attacks silent? Well, there are many reasons for this with the simplest one being that some people simply have a higher pain threshold causing them to ignore symptoms that the rest of us could not. Secondly, there are a number of medical conditions such as kidney disease or diabetes that can damage the nerves that signal pain and as such “blunt” the sensations that a heart event usually invokes.

Lastly, lots of us are good at brushing aside legitimate medical concerns by down-playing their significance (“it’s nothing, just a little heartburn”) so as not to wreck our busy schedules or concern others who care about us. SMI’s occur more commonly in older people, especially those over the age of 75 and they are seen more commonly in men than in women.

The symptoms of SMI’s are often very mild and may last for just a brief period of time so they truly are often easy to ignore. While you may still feel pain, it won’t be anything close to that felt in a typical heart attack. It may be felt as more of a discomfort in the upper abdomen, back or jaw. Some have compared it to the straining of a muscle. Shortness of breath could also be a sign of a SMI. Mild pain in the throat or chest that feels like indigestion or heartburn could also be an indicator that you are currently experiencing a SMI.  Lastly a sense of fatigue, light-headedness, nausea or the breaking out in a cold sweat are all common but hard to pinpoint those signs of an SMI as well.

All heart attacks are very serious events regardless of how large and aggressive they were. They can of course kill you but for those that live, they increase the risk of developing conditions such as congestive heart failure which compromises the ability of the heart to pump blood leading to excessive fatigue, a near constant feeling of being short of breath and legs that tend to swell with fluid. Treatment for a silent heart attack is the same as that for a regular heart attacks and is aimed at limiting risk factors so that your chances of having a second one (which are often more damaging than the initial heart event) can be reduced.

Many doctors will order a stress test which can provide both the patient and the doctor with two pieces of vital information. One, is it can give you an idea of how much exercise your heart can handle safely. Exercise is critical to continued heart health but there is definitely such a thing as too much and this test will give the experts a better handle on how to advise you regarding future activities.

The other piece of information this test can provide is that during the test, your heart will likely go into an ischemic state, meaning that it is not receiving enough blood. Even people who have had silent heart attacks will feel “something” when this happens and people can be taught that when they experience this particular sensation (such as mild discomfort in the shoulder, sudden fatigue or whatever) , they need to stop what they are doing immediately and follow whatever course of action their doctor told them to (such as using a spray of nitroglycerin).

With the right lifestyle choices and new medications, people who have had a silent heart attack in the past can have a good and healthy life for decades to come. For more information about this or any other health related questions, contact your pharmacist.