Skip to content
hand pen paper

Understanding AFib: Why do I have this? Should I take blood thinners?

In the second piece in a the Understanding AFib series, physician Randall Stafford examines which patients should use blood thinners.

In my clinical practice, I've found that patients with the irregular heart rhythm atrial fibrillation (AFib) do the best when they contribute to their own care by:

  • Learning the difference between AFib and a normal heart rhythm.
  • Eating a heart-healthy diet that slows down underlying problems linked to AFib.
  • Gaining knowledge about AFib medications and taking them consistently.

Oftentimes, patients wonder why them — why is their heart not working as it should?

About 9 percent of people over 65 have atrial fibrillation. Although diseased arteries in the heart often lead to AFib, other causes include high blood pressure, obesity, and excessive alcohol use. It is also more common in those of European descent.

AFib comes in several forms; often it is permanent with no possibility of a return to a normal rhythm. Other times, it can come and go (a condition called paroxysmal AFib, the type that George H., who we met in our last blog post, has).

As I mentioned  there, preventing a stroke in AFib patients is a major consideration.

Unfortunately, people with this heart condition are 4 to 5 times more likely to have a stroke. AFib’s irregular heartbeat may lead to small blood clots that form within the heart. When these blood clots travel to the brain, they can produce major damage by blocking essential blood flow and causing a stroke. While AFib is a serious health condition, the good news is that the use of blood thinners drastically reduces the chance of having a stroke.

All medications have risks. While reducing the blood’s ability to clot makes blood thinners incredibly useful drugs, they also have significant risks. They must be taken carefully and only with a doctor’s advice. The most common side effect of blood-thinning medications is unwanted minor bleeding or bruising. Serious bleeding, while less common, is most likely to occur in the digestive tract, particularly in the lining of the stomach.

Since there are inherent risks in taking blood thinners, deciding who is a good candidate to use them is always a balancing act.

It is critical to carefully weigh the prevention of a future stroke against the potential for increased bleeding. Doctors frequently use a stroke risk scoring system called CHADS2-VASc to help with the decision about who should take blood thinners. The guidelines for the scoring system follow a couple basic rules:  Blood thinners are recommended if any ONE of these risk factors is present:

  • Age 75 years or older,
  • A past stroke or mini-stroke, or
  • A past blood clot.

Blood thinners are also favored if any TWO of these risk factors are present:

  • Female
  • Age 65-74 years,
  • Heart failure,
  • High blood pressure,
  • Diabetes, or
  • Vascular disease (e.g., chest pain, carotid artery disease, heart attack).

The more risk factors you have, the greater the chance of having a stroke and the more reason to use blood thinners to protect against a stroke. For those with none of these risk factors, the possibility of harm from these drugs is greater than the possible benefits. In general, the risk of having a stroke is the same whether AFib is permanent or only occurs occasionally.

We introduced George H. in our last blog post. He is a 71-year-old retired engineer with episodes of AFib. Based on the risk factors for stroke reviewed above, should George take blood thinners?

Let’s check out his risk factors: He is 71 years-old and taking medications for high blood pressure, although he has none of the other listed stroke risk factors. Based on his age (1 point) and having high blood pressure (1 point), George’s risk of a stroke is 2 percent per year. Following the guidelines, the doctor started him on a blood thinner. But as we’ll see, George came to have some second thoughts about this, his blood thinners were more than he bargained for.

Knowing your stroke risk score is a critical piece of information for every patient with AFib. Several online tools are available to help calculate stroke risk scores. You can use this easy-to-use, online risk scoring calculator to help assess your situation and then work with your doctor to review your personal calculations.

This is the second in a series of blog posts called Understanding AFib to help patients with atrial fibrillation live healthier lives. The first blog post explained AFib, while the next blog post will review blood thinning drugs. George H. is an actual patient with some details altered to protect his confidentiality.

Randall Stafford, MD, PhD, is a professor of medicine at Stanford and practices primary care internal medicine. Stafford and Stanford cardiologist Paul Wang, MD, lead an American Heart Association effort to improve stroke prevention decision-making in atrial fibrillation.

Photo by rawpixel

Popular posts

Category:
Biomedical research
Stanford immunologist pushes field to shift its research focus from mice to humans

Much of what we know about the immune system comes from experiments conducted on mice.  But lab mice are not little human beings. The two species are separated by both physiology and  lifestyles. Stanford immunologist Mark Davis is calling on his colleagues to shift their research focus to people.