Featuring Dr. Graham Wong, MD, MPH, FRCPC, FACC, Cardiologist

Duration: 4 minutes, 49 seconds

Atrial fibrillation is the most common rhythm problem in the world. It can affect anybody, although it does tend to cluster in people who are a little bit older and those with high blood pressure.

The symptoms of atrial fibrillation speak to the irregular electrical stimulation of the heart, as opposed to a single dominant electrical signal, and so patients can feel an irregular heartbeat subjectively felt as palpitations.

Because the electrical instability of atrial fibrillation causes the heart to beat irregularly the blood flow in that heart becomes irregular, and the current thinking is that the irregular flow of blood in a heart under the control of atrial fibrillation can form little eddy currents and the blood can become static.

And when blood becomes static and becomes sluggish it can form little blood clots, and if those blood clots then leave the heart and lodge up in the brain, that can cause the most dreaded complication of atrial fibrillation, which is stroke.

The risk of stroke with atrial fibrillation is not the same for any individual. And the more we understand atrial fibrillation, the more we realize that it’s not the atrial fibrillation itself that causes the stroke, it’s the company in which it keeps.

And so when we are faced with a patient with atrial fibrillation, what we try to do is estimate the risk of a stroke by looking for the other risk factors that we know that when they coexist with stroke, will increase to a point where we would need to consider starting patients on blood thinners.

Some of these risk factors that will increase your risk of stroke in the company of atrial fibrillation include increasing age, female gender, high blood pressure – treated or otherwise, diabetes – treated or otherwise, congestive heart failure – otherwise known as water on the lungs, and the presence of a prior stroke.

What clinicians do is they add up these risk factors in an ordinal fashion. And if you have more than one risk factor, we believe that your perceived risk of stroke is high enough that we would normally recommend blood thinners to minimize or reduce that risk.

The risk of stroke is in no way related to whether or not patients feel their atrial fibrillation or are asymptomatic, and up to 30% of patients with atrial fibrillation have no idea that their rhythm is irregular. And so the absence of symptoms in no way protects you from the risk of a stroke.

Your doctor may suggest several choices for blood thinners depending on your perceived risk of stroke. These would include aspirin, Warfarin or some of the newer agents which we call the direct-acting or novel anticoagulants.

For several decades Warfarin was the gold standard in terms of our choice of blood thinner. It’s been shown to be highly effective at reducing the risk of stroke, and reasonably safe. The problem with Warfarin is it’s a very unreliable drug insofar that it binds to all sorts of proteins and other materials in the body, and needs to be monitored and regulated quite closely.

So patients on Warfarin need to go for regular blood tests and their doses need to be increased or decreased depending on the level of Warfarin. In addition, Warfarin is influenced by other drugs, food and drink, and so it’s very difficult to maintain a therapeutic dose of Warfarin, and patients find that going to the lab is often very inconveniencing for them.

Recently, a newer class of blood-thinning drugs has been introduced that have found to be superior to Warfarin, unlike Warfarin do not interfere with food or drink, can be taken once or sometimes twice a day, and do not require monitoring and can be taken on a fixed dosing schedule.

These drugs have much less risk of bleeding in the head, and either an equivalent or lower risk of total bleeding with at least an equivalent reduction in stroke compared to Warfarin, and are now considered the preferred agents for blood thinning amongst patients with atrial fibrillation.

It's very important that if patients are prescribed blood thinners for the purposes of reducing stroke, that they must take their medications as scheduled and as recommended by their doctors. Missing even one or two doses could put you at risk for a stroke, because these blood thinners need to be at a certain level in your body for them to be effective.

There are things you can do to minimize the chance you will develop atrial fibrillation by adopting healthier lifestyle choices. We know that one of the biggest predictors of atrial fibrillation is high blood pressure, and so anything you can do to reduce your blood pressure, either with pharmacological or non-pharmalogical interventions, can potentially reduce your risk of developing atrial fibrillation as a consequence.

If you have any additional questions regarding atrial fibrillation and stroke prevention, I would strongly urge you to speak to your family physician, stroke neurologist or local internist or cardiologist.

Presenter: Dr. Graham Wong, Cardiologist, Vancouver, BC

Local Practitioners: Cardiologist