Can exercise trigger a heart attack?

It seems like everyone has a story about someone they know who suffered a heart episode at the gym, or while out on a run or right after climbing stairs. We asked Mark O’Shaughnessy, MD, Parkview Heart Institute, to explain whether exertion can in fact put someone at risk.

Is there a correlation between exertion and heart attacks?

True heart attacks are caused by a rupture of the atherosclerotic plaque with subsequent thrombus (blood clot) formation within the artery, disrupting blood flow down the artery. Fundamentally, we do not know why the stable plaque in the coronary artery ruptures, resulting in a heart attack. Exertion does not appear to be a risk factor for plaque rupture and the events are likely coincidental and not truly causative. If a patient has a hemodynamically significant lesion (>70%), exertion will cause symptoms like angina (pain in the chest, shoulders, arms and neck), but the patient is unlikely to have a myocardial infarction (MI) as long as the pain subsides with rest.

Would it ever be possible that exertion could trigger a heart episode?

As above, if a patient has a significant flow limiting lesion (typically >70%) exertion can cause angina. When we exert ourselves, we need to increase blood flow to the exerting muscles, which requires the heart to work harder. The heart needs to increase its own blood flow if it is working harder and if there is an abnormal narrowing (stenosis) of the supplying vessels that limits the amount of blood that gets to the muscle, it could result in symptoms. But again, a heart attack is a complete occlusion of the vessel by thrombus resulting from a ruptured plaque.

What can people do to reduce their risk?

Risk factor modification is the best way to prevent heart attacks and heart disease. Control your blood pressure, glucose, cholesterol and quit smoking to minimize the danger. Moderation in diet and regular exercise are significant lifestyle modifications that go a long way for prevention as well.

Do the benefits of exercise outweigh the risks?

The benefits of exercise far outweigh the minimal risks of a cardiac event. If you look at the relative risk of an MI in people who exercise 4+ days/week versus those who do less, it is 1.3 versus 6.9. Exercise is protective, but of course it is not a 100 percent guarantee. You still need to know your other risk factors and modify them.

What are some safety measures people can take while exercising?

To be safe, you need to know your numbers and make sure you have modified areas of risk. Be aware of the typical and atypical symptoms of heart disease and notify your physician if you are concerned you are having any of these symptoms.

Knowing how to do CPR and use an AED machine are important for saving lives as well.

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