atrial fibrilationAmongst some definitions of the web search one can define, Atrial fibrillation is an irregular and often rapid heart rate that commonly causes poor blood flow to the body. Stroke on the other hand is, a medical emergency. Strokes happen when blood flow to your brain stops. Within minutes, brain cells begin to die. There are two kinds of stroke. The more common kind, called ischemic stroke, is caused by a blood clot that blocks or plugs a blood vessel in the brain. The other kind, called hemorrhagic stroke, is caused by a blood vessel that breaks and bleeds into the brain.

How does one apply population data to the person in front of you? The patient with atrial fibrillation and one additional risk factor for stroke presents this very challenge. You aim to provide benefit—stroke prevention—but you risk doing harm—bleeding.

Provocative New Study

recent study [1] from a group of Swedish researchers (led by Dr Leif Friberg [Karolinska Institute, Stockholm, Sweden]) published in the Journal of the American College of Cardiology suggests that the previous estimates of the risk of ischemic stroke in AF patients with one risk factor may have been too high.

The original question remains: “Doc, should I take an anticoagulant or not?”

We assume the absolute risk reduction of anticoagulants is similar across risk groups (maybe), so the net benefit hinges on weighing that amount of risk reduction against the increase in bleeding risk.

Expert opinions 

To learn more, I reached out to experts in the area.

Dr Suneet Mittal (Valley Hospital Health System, Ridgewood, NJ) tweeted that, contrary to the typical cardiology view, not all strokes in AF patients come from the atria. Good point.

Dr Torben Larsen (Aalborg University Hospital, Denmark) said in an email, regarding the Friberg et al paper, that the “devil is in the detail of the methodology.” Excluding patients exposed to warfarin creates a “conditioning-on-the-future” selection bias, wherein the “predefined” nontreated patient group is inherently lower risk, he noted.

Until then, doctors will have to accept uncertainty, discuss it frankly with our patients, and then be mindful of the perspective with which each patient interprets (feels) the benefits and risks of treatment—or no treatment.

The neurosurgeon and daughter of a stroke victim will likely choose to gamble on different choices.

Originally excerpts are from medscape-JMM updates on cardiology stroke and atrial fibrillation

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