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Secondary Stroke Prevention in Afib: Is Oral Anticoagulation Effective?

Over the past few years, there has been a tremendous influx of research dollars into the healthcare field. These have yielded a variety of new diagnostic and treatment modalities for diseases that previously had none. Unfortunately, several diseases continue to plague the US healthcare system. Among these are heart disease, obesity, diabetes, and hypertension. These diseases have a number of important health consequences — including an increased propensity for affected patients to develop blood clots.
There are many different forms of heart disease– atrial fibrillation among them. When the atria of the heart do not pump effectively, blood tends to pool in these chambers. Blood stasis leads to increased blood clotting and emboli. This can lead to MI, pulmonary emboli, and strokes. This begs the question: should patients with atrial fibrillation be placed on prophylactic anti-thrombotic therapy? A recent research study sought to answer this exact question.

Overview: Antithrombotic Therapy in Patients with Atrial Fibrillation
There are lots of different types of antithrombotic therapy. One of these is oral medication, which patients at an increased risk of stroke may benefit from. This includes patients with sickle cell disease, those who are recovering from surgery, and individuals with atrial fibrillation. While there is a lot of attention on thrombosis prophylaxis in the hospital setting, antithrombotic therapy is often underused out in the community. A few important points on atrial fibrillation and stroke include:

  • Those with atrial fibrillation are 500% more likely to have an ischemic stroke when compared to the average individual
  • About a quarter of all strokes are in some way attributed to atrial fibrillation
  • Oral anticoagulation therapy can reduce the risk of stroke in individuals with atrial fibrillation by greater than 60%
  • Even though there are strict guidelines for when people with atrial fibrillation should be placed on these oral anticoagulants, these agents are still markedly underused

It is important for every healthcare provider to take note of when people with atrial fibrillation should be placed on an oral anticoagulant. Patients with at least two of the following risk factors (according to the CHADS2) should be placed on prophylactic medications.[1] These are:

  • Congestive heart failure
  • Hypertension
  • Age over 74 years (counts as two points)
  • Diabetes
  • History of stroke
  • Transient ischemic attack
  • Vascular disease
  • Age between 65 and 74 
  • Female gender
  • Systemic emboli (2 points)

Antithrombotic Rx in Ischemic Stroke Patients with AFib
study published by the JAMA Open Network took a look at the impact of antithrombotic treatment in individuals with atrial fibrillation who presented with an ischemic stroke.[2] The study sought to examine the antithrombotic treatment patterns in these individuals both prior to their stroke and after it. All of these individuals had a CHADS2score of 1 or higher (for men) or 2 or higher (for women). They presented with an ischemic stroke between 2004 and 2017. 

Those who survived longer than 100 days after their discharge were broken up into three different groups with different antithrombotic therapies. One group received oral anticoagulation therapy; a second got antiplatelet therapy alone; and a third received no antithrombotic therapy. Their thromboembolic events and bleeding complications were tracked long-term.

Study Results
Over the study period, there were more than 30,000 individuals who were evenly divided among the three groups. The researchers found that about a quarter of the patients prior to their stroke were not receiving any antithrombotic therapy alone; however, over time, individuals started to present more and more frequently having been on anticoagulation therapy, indicating a shift in the practice over time. Most importantly, over a ten-year follow-up period, 17% of those receiving oral anticoagulation therapy experienced a recurrent thromboembolic event while 21% of those in the antiplatelet group and 21% of those in the “no antithrombotic therapy group” experienced another thromboembolic event. The 95% confidence interval for the adjusted hazard ratio was between 0.73 and 0.89. The researchers noted that there was no significant increase in bleeding complications for those receiving oral anticoagulation therapy.

Take-Home Messages: Proper Prophylaxis for Individuals with Atrial Fibrillation
The key take-home is that individuals with atrial fibrillation are at an increased risk of stroke and other embolic events due to blood stasis in the atria.[3] Those who qualify for anticoagulation therapy based on their CHADS2 score should be placed on prophylactic anticoagulation therapy. This means oral therapy, which has been proven to be both effective and safe based on this research study and other academic, peer-reviewed research papers. Those who receive proper anticoagulation therapy are at a reduced risk of recurrent embolic events.

Last updated on 9/25/19.

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