March 16, 2010
Should everyone take an aspirin a day?
If you are having a heart attack, chewing a full-strength aspirin tablet can be a lifesaving move. If you have heart disease, have had a heart attack or stroke, or are at very high risk for having one, taking a low-dose aspirin every day is part of a proven strategy for preventing one of these life-changers. Aspirin makes blood platelets less “sticky.” This limits the formation of clots in the bloodstream, which can trigger heart attacks and strokes. But what if you are relatively healthy? Will taking aspirin help you keep heart attack, stroke, and other forms of cardiovascular disease at bay?
If taking aspirin were without side-effects and completely risk free, it might make sense for everyone with heart disease, or just worried about it, to take it. But aspirin does have risks. Reducing blood’s clotting potential can lead to hemorrhagic stroke (bleeding inside the brain). In the stomach, aspirin can cause everything from a feeling of mild heartburn to bleeding ulcers. Severe gastrointestinal bleeding can be deadly.
The benefit-risk balance
It’s the balance of benefits and risks that guides who should take aspirin for primary prevention — preventing heart attack, stroke, or another manifestation of cardiovascular disease in seemingly healthy people.
Researchers from six large primary prevention trials of aspirin pooled their data and analyzed them as if they were from a single large trial. It’s a legitimate technique called meta-analysis. In this relatively healthy group of 95,000 volunteers, the reduction in heart attacks and strokes in people taking aspirin was almost counterbalanced by major bleeding in the gastrointestinal system and the brain. The researchers concluded that for individuals without previously diagnosed cardiovascular disease, “aspirin is of uncertain net value.”
Another meta-analysis showed only a modest overall benefit, if any, for aspirin among people with diabetes but no cardiovascular disease, and it had little impact on heart attack or stroke. When the researchers analyzed the data by sex, aspirin reduced the risk of heart attack in men but not women.
The British journal Drug and Therapeutic Bulletin also weighed in on the topic in November 2009. After reviewing and analyzing information from relevant primary prevention studies, the journal’s editors concluded that the benefits and harms “may be more finely balanced than previously thought,” and aspirin should not be recommended as an across-the-board option to help healthy people prevent heart attack and stroke.
Finding the tipping point
Don’t take aspirin just because you’ve heard it can help prevent a heart attack or stroke. It can, but it can also do some damage. There’s no exact tipping point at which it makes sense to start taking an aspirin a day. If you are healthy, haven’t been diagnosed with heart disease or other cardiovascular disease, and don’t have risk factors for them, aspirin probably isn’t for you. You’ll reap little benefit while exposing yourself to side effects you’d rather stay away from. The less healthy your heart and arteries, the more likely the advantages of taking aspirin will outweigh any risks.
It isn’t the easiest decision to make. If you are in the gray zone, talking with your doctor could make it more black and white.
Does heart rate affect blood pressure?
Q. When doctors interpret a blood pressure reading, should they also consider the heart rate? I am a 78-year-old man and have had high blood pressure (under control) for more than 40 years. I frequently monitor my blood pressure at home, resting for five minutes before I take the reading. My blood pressure is often higher when my heart rate is close to its usual resting rate (about 50 beats per minute) and lower when my heart is beating faster than that. Can the body’s demands that cause higher blood pressure be partially satisfied by a faster heart rate?
A. First, let me congratulate you on monitoring your blood pressure at home. This is a great way for you to take control of your high blood pressure, and a good step toward preventing a stroke. Knowing that your blood pressure at home is under consistent control is more important than getting isolated readings at the doctor’s office. You are also resting before taking the reading, and this is important to avoid spuriously high readings that happen when someone rushes around, and then sits down quickly to take a blood pressure reading. (To learn more, watch our video "Measuring blood pressure at home.")
Heart rate and blood pressure are intimately related. Nerves and hormones constantly monitor and balance the heart rate and blood pressure. It is true that an isolated increase in blood pressure can drop the heart rate a little. But the reflexes that control blood pressure and heart rate are not simple. Sometimes, both heart rate and blood pressure can fall simultaneously, as happens with a typical fainting episode. Often, both heart rate and blood pressure rise together, such as when you exercise, get angry, or have an overactive thyroid.
I suggest that you write down your heart rate along with your blood pressure, and bring that information to your doctor every time you see him or her. Heart rate trends can provide useful data on your cardiovascular health. A consistently low heart rate, like yours, can indicate that some medicines might not be good for you. A consistently high heart rate can suggest that the thyroid be checked.
— Richard Lee, M.D.
Associate Editor, Harvard Heart Letter