November 5, 2013
News Review From Harvard Medical School -- Rhythm Problem May Increase Heart Attacks
People with one type of abnormal heart rhythm are more likely to have heart attacks, a new study concludes. The study looked at the relationship between heart attack and atrial fibrillation (AF). With AF, the upper chambers of the heart do not beat normally. They quiver in a fast, irregular pattern. Heart attack is known to increase the risk of AF, but doctors have not known if the reverse is true. This study examined the issue by looking at records for nearly 24,000 people. They did not have coronary artery disease when the study began. More than 1,600 of them had AF. During a 7-year period, 650 people in the study had heart attacks. People with AF were nearly twice as likely as others to have heart attacks. The risk was especially high among women and black men. The study does not prove that AF actually caused the heart attacks. More research is needed, the authors said. The journal JAMA Internal Medicine published the study online. HealthDay News wrote about it November 5.
By Lori Wiviott Tishler, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
Atrial fibrillation (AF) is a very common irregular heart rhythm. It occurs when the top part of the heart, called the atrium, fails to beat in a regular pattern.
Usually, it's not an immediate threat to someone's life. But atrial fibrillation can cause people to feel palpitations and fatigue. Some people with this condition just "don't feel quite right." Over time, AF also increases people's risk of a stroke. That's because a blood clot can form in the atrium and travel to the brain.
In general, doctors have often explained to patients that a heart attack puts them at risk for AF, but that AF itself does not cause heart attack. This article turns that idea on its head.
The authors found that AF does, in fact, put people at risk for a heart attack. In a large study of nearly 24,000 people, the authors found that more than 1,000 had AF. People with AF had nearly twice the risk of heart attack as people without AF.
The researchers adjusted their numbers to account for other factors that can increase people's risk of a heart attack. Still, the increased risk with AF continued. Women and blacks had greater risks than white men.
The authors conclude that AF can lead to heart attack, just as heart attacks can lead to AF. This is called bidirectional risk. The authors of a related editorial agree with the finding. They suggest that doctors need to change the way they think about both heart attack and AF.
The study included a very large group of people. The authors describe possible explanations why people with AF have an increased risk of heart attack. These could include increased inflammation and risk of blood clots.
The study did have possible limitation. For example, researchers might have misclassified some people with AF or heart failure. By design, the study included only people who were black or white. Therefore, the results may not apply completely to other groups.
Still, this was a large, well-done, thoughtful study that brings some new ideas to a common public health issue.
What Changes Can I Make Now?
AF is a common irregular heart rhythm that affected more than 2.6 million Americans in 2010. Many people have no symptoms at all. Others may feel:
- Shortness of breath
- Chest pain
Diagnosis is simple. Doctors can often hear AF with a stethoscope or feel it by taking your pulse. We confirm it by doing an electrocardiogram. This is a painless test that measures the electrical activity of the heart.
If you have atrial fibrillation, the treatment depends on the cause. You might need to do no more than take an aspirin a day. Your doctor also may prescribe medicines to slow down the rate or regularize the rhythm of the heart. Rarely, people might need surgery or another procedure to help stop AF.
When people develop AF, doctors think carefully about their risk of stroke. Treatments are based on helping decrease stroke risk as well as helping people to feel and function better.
If you have been diagnosed with atrial fibrillation, be sure to take your medicines as prescribed. You also can take other steps to help reduce your risk of heart attack:
- Get regular exercise.
- Choose a healthy diet.
- Maintain a healthy weight.
- Don't smoke or use other tobacco products.
- Keep your blood pressure and cholesterol levels in a healthy range.
- If you have diabetes, keep your blood sugar levels under control.
What Can I Expect Looking to the Future?
This study presents such an interesting result that I think we can expect to see much more research in this direction. I expect that we'll see studies that look carefully at other ethnic groups. I think we'll also see research on the level of cells and molecules to find out how AF might increase the risk of heart attack.