It's not her first brush with heart disease. Last year, Braxton told WebMD about her 2004 brush with pericarditis -- inflammation of the tissue surrounding the heart.
People with microvascular angina, also known as cardiac syndrome X, suffer pain when doing strenuous exercise. Yet in her first appearance on Dancing with the Stars, 40-year-old Braxton was one of the top-rated dancers.
In an interview with E! News Now, Braxton said that after hearing of her new diagnosis, she planned to take a year off to let her body and mind heal. Then she changed her mind.
Is that wise? What is microvascular angina? How will it affect Braxton's performance? Her career? Her life?
WebMD consulted with top heart doctor William O'Neill, MD, executive dean for clinical affairs and professor of medicine and cardiology at the University of Miami Miller School of Medicine. We asked O'Neill:
- What is angina?
- What is microvascular angina (cardiac syndrome X)?
- How do doctors diagnose microvascular angina?
- Did Toni Braxton's previous pericarditis cause her microvascular angina? Might her doctors have misdiagnosed her microvascular angina four years ago?
- How is microvascular angina treated?
- Is there a lesson here for other people?
What is angina?
"The term angina means chest discomfort. It is the medical term for a symptom: heart pain. It is brought about when there is a lack of blood supply to a portion of the heart muscle.
"If this happens, the person feels discomfort. People feel this differently. Nobody has exactly the same feeling with angina. Some feel it as a pressure or a burning. Most people do not feel true pain. Usually it is described as an elephant sitting on one's chest, or as if a giant hand were squeezing your chest.
"Some people don't feel it at all. People with diabetes are notorious for not feeling angina. This is called silent ischemia. The other thing that is very common is that people get very short of breath -- without pain -- as a manifestation of angina. They say, 'Doc, I feel fine, but every time I climb stairs I get really short of breath.'"
"When anything blocks blood flow to the heart, the heart has to start pumping harder, and that part of the heart becomes ischemic and you start having pain."
What is microvascular angina (cardiac syndrome X)?
"In 95% of cases, lack of blood flow to the heart is due to blockages in one or more of the three main coronary arteries. Somewhere under 5% of the time, instead of major artery blockages, people have atherosclerosis in very small arteries.
"Picture the heart as the trunk of a tree. To get blood to the muscles, the tree roots branch out into smaller and smaller vessels. When these little vessels get diseased, as you exercise, you can't get enough blood to the heart."
How do doctors diagnose microvascular angina (cardiac syndrome X)?
"Cardiac syndrome X is a diagnosis of exclusion. We don't have equipment that does microscopic dissections of these small blood vessels. So this is mainly diagnosed by symptoms.
"To diagnose this, we try to bring on pain in a stress test. We have patients walk rapidly, so the heart beats very fast. If there is angina, we do a coronary angiography to look for blockages in the major arteries. That is probably what happened to Toni Braxton. If she had angina and no blockages in major arteries, that's probably when they diagnosed microvascular angina."
Did Toni Braxton's previous pericarditis cause her microvascular angina? Might her doctors have misdiagnosed her microvascular angina four years ago?
"Pericarditis could not have led to microvascular angina. There are definite changes on medical tests that lead to a diagnosis of pericarditis, so it is hard to conjecture as to how that diagnosis was made. But let us assume she did have pericarditis: That is not going to lead to angina."
How is microvascular angina treated?
"In my armamentarium, I use drugs to dilate the coronary arteries: long-lasting nitrates such as the nitroglycerin patch; then calcium-channel blockers such as verapamil [brand names include Calan, Covera, Isoptin, and Verelan] or diltiazem [brand names include Cardizem, Cartia, Dilacor, Diltia, and Tiazac].
"Then the other new drug which is really promising is Ranexa, which works by a totally different mechanism on the metabolism of the heart. It is an incredible anti-angina drug but does not have FDA approval for that indication. I have shifted a lot toward use of Ranexa for these patients. [O'Neill has no financial link to the makers of this drug].
"Exercise is also a good thing to do. What I tell people is to exercise to the threshold of symptoms, then cut back. So if you get angina after running three miles on the treadmill, cut back to two miles, then gradually build up. The more you exercise, the more you are able to exercise."
Is there a lesson here for other people?
"The value of people learning about microvascular angina from Toni Braxton is that middle-age women just don't believe they have heart disease. They feel pain with exercise, and don't do anything about it.
"The message here is if you have discomfort when exercising, that is abnormal. There is something wrong and you should look into it. Overwhelmingly, this turns out to be coronary artery disease, but occasionally it is cardiac syndrome X. It would be good if more women knew about this."