Dr. Day is a cardiologist/electrophysiologist at the Intermountain Medical Center Heart Institute in Salt Lake City, Utah. He graduated from Johns Hopkins Medical School and completed his residency and fellowships in cardiology and electrophysiology at Stanford University. He is the former president of the Heart Rhythm Society and currently serves as the president of the Utah chapter of the American College of Cardiology.
13 Reasons Why CHADS-VASc May Not Be the Best for Atrial Fibrillation Stroke Prevention
Wouldn’t it be great if we could accurately predict who is most at risk for atrial fibrillation strokes? Despite the aggressive use of blood thinners in the new CHADS-VASc guidelines, there is no proof yet that stroke rates have gone down. In this article, I discuss 13 reasons why the CHADS-VASc scoring system may not be the best for atrial fibrillation stroke prevention.
What is CHADS-VASc?
For those readers who may be unfamiliar with the CHADS-VASc scoring system for atrial fibrillation stroke prevention, let me give you a quick primer. CHADS-VASc is an acronym for some of the stroke risk factors. Based on how many of these risk factors you have, you can calculate your score. If your score is one or higher, you are a candidate for life-long blood thinners like warfarin (Coumadin), Pradaxa (dabigatran), Xarelto (rivaroxaban), Eliquis (apixaban), or Savaysa (edoxaban).
To calculate your CHADS-VASc score, you get one point for congestive heart failure, high blood pressure, an age of 65 to 74, diabetes, vascular disease (history of a blockage in any artery), or sex (female gender). If you have had a stroke or TIA, you get two points. Likewise, if your age is 75 or older, you also get two points.
This CHADS-VASc scoring system has been the “Bible” for blood thinner use in Europe since 2012 and the US since 2014. Since 2014, this new CHADS-VASc scoring system has had a huge impact on my atrial fibrillation practice.
How CHADS-VASc Has Changed my Practice
At least two-thirds of my cardiology practice is atrial fibrillation. Other than the dramatic advances in the field of catheter ablation, the most significant change I have seen in atrial fibrillation management has been the CHADS-VASc scoring system for atrial fibrillation stroke prevention.
The reason why CHADS-VASc has had such a massive impact on my practice is that it requires most of my previously low-risk atrial fibrillation patients to now take blood thinners for the rest of their lives. Despite all of the blood thinners now being prescribed, I’m not convinced things have improved. As we have been less than impressed with the CHADS-VASc scoring system, our hospital has created a new scoring system which may be better than CHADS-VASc.
13 Reasons Why CHADS-VASc is Wrong for Atrial Fibrillation Stroke Prevention
The low threshold to start blood thinners with the CHADS-VASc scoring system never really made sense to me. And here are 13 reasons why it may not be the best for atrial fibrillation stroke prevention.
1. It Doesn’t Predict the Risk of Blood Clots in the Heart
Fully 90% of atrial fibrillation strokes arise from blood clots in the left atrial appendage of the heart. Thus, if CHADS-VASc worked, you would expect this scoring system to predict the risk of developing a blood clot in the left atrial appendage of the heart. Unfortunately, studies show that it doesn’t predict the risk of blood clots in the heart.
2. It Wrongly States that All Women Are Candidates for Blood Thinners
According to CHADS-VASc, all women are candidates for life-long blood thinners. Personally, I don’t think that the female gender should count as an atrial fibrillation stroke risk factor. While there are some studies suggesting women might be at higher risk of stroke, I can find plenty of other studies arguing the opposite.
3. No Credit is Given for an Ablation
Even if a catheter ablation has eliminated your atrial fibrillation, CHADS-VASc gives you no credit. Despite many studies showing that successful ablation patients have a very low risk of stroke, this scoring system ignores the evidence.
4. There is No Proof it is Better than the Old Scoring System
You would think that it would take compelling evidence to change a scoring system that determines whether or not you should swallow down a blood thinner for the rest of your life. Sadly, that wasn’t the case.
This new CHADS-VASc scoring system was determined by retrospective database number crunching. In other words, there was no definite proof that it was any better than the previous scoring system it replaced. Even worse is that there are now studies showing that it is not as good as what we previously had.
5. No Credit is Given for the Motivated Patient
Regardless of the study, bad things are much more likely to happen to people who aren’t proactive about their health. And when it comes to atrial fibrillation stroke prevention, the same holds true.
For the motivated patient who tracks their daily heart rhythm, it just doesn’t make sense to take a blood thinner every day when you may only have atrial fibrillation once or twice a year. Indeed, at least three small studies (1, 2, 3) have shown that it is safe to only take a blood thinner on an as needed basis for people who are tracking their rhythms. Despite this mounting evidence, CHADS-VASc gives no credit to the motivated patient.
6. It Ignores Reversible Causes of Atrial Fibrillation
Just because you have one episode of atrial fibrillation doesn’t mean that atrial fibrillation will be a lifelong problem for you. Indeed, many cases of atrial fibrillation are completely reversible.
For example, drinking too much alcohol or getting pneumonia are both reversible causes of atrial fibrillation. In other words, sobriety and staying healthy can put atrial fibrillation into remission.
Sadly, CHADS-VASc gives no credit to people with reversible causes of atrial fibrillation. Even though studies show that blood thinners don’t work very well for reversible causes of atrial fibrillation, once again CHADS-VASc doesn’t consider this.
7. It Overlooks the Brain Microbleed Dementia Risk
I suspect that most cardiologists are unaware of brain microbleeds. While most brain microbleeds don’t cause any symptoms, the more of them you get, the worse your brain functions. Indeed, studies show that people on blood thinners may get more of these brain microbleeds than people not taking blood thinners. And the more brain microbleeds you get, the higher your dementia risk.
8. It Assumes People Aren’t Taking Warfarin Anymore
One of the primary arguments of why everyone should take blood thinners for life with CHADS-VASc is that the new blood thinners are so much safer. While the new blood thinners are much safer than warfarin, the problem is that warfarin use isn’t declining.
When the new blood thinners were released, we were sure that all of the Coumadin (warfarin) Clinics would go away. In contrast, the number of patients on warfarin has only increased.
At least 99% of my patients on warfarin would love to take one of the new blood thinners. The only problem is that they can’t afford them. For people on a fixed income, there is no way they can afford the annual $5,000 price tag to take one of these drugs. And if you can’t afford one of the new blood thinners, then the aggressive blood thinner use called for by the CHADS-VASc scoring system may not make sense.
9. Recommending Blood Thinners for a Score of 1 or Higher is Misguided
According to the CHADS-VASc scoring system, a score of one or higher is an indication for life-long blood thinners. While some studies may suggest a benefit for the low score of one, others don’t.
For example, one study reports that blood thinners for a CHADS-VASc score of one is misguided. Another highly credible study argues that the cut off for blood thinners should be at least a score of three. The bottom line is that we really don’t know what the cut off for lifelong blood thinners should be. In my mind, a cut off of “two” was an arbitrary decision.
10. It Disregards the Left Atrial Appendage
As 90% of atrial fibrillation strokes arise from the left atrial appendage, why does CHADS-VASc ignore this important structure in your heart? For example, studies from our hospital show that the bigger your left atrial appendage, the higher your risk of stroke.
Also, the shape of your left atrial appendage matters when it comes to your risk of stroke. In particular, the chicken wing pattern carries a very low stroke risk. To find out the size or shape of your left atrial appendage, your cardiologist can quickly order a CT scan of your heart.
Lastly, the better your left atrial appendage contracts, the lower your stroke risk. How well your left atrial appendage contracts is something that is best determined by a transesophageal echo (TEE).
11. It Dismisses the Type of Atrial Fibrillation You Have
Whether or not your atrial fibrillation is paroxysmal (starts and stops on its own) or persistent (doesn’t terminate on its own), determines your stroke risk. For example, studies show that persistent atrial fibrillation has about twice the stroke risk of paroxysmal atrial fibrillation. Sadly, CHADS-VASc completely dismisses this. Regardless of your atrial fibrillation type, CHADS-VASc doesn’t care.
12. It Assumes Your Atrial Fibrillation Burden Doesn’t Matter
Common sense would tell you that when it comes to your atrial fibrillation stroke risk, being out of rhythm all the time is probably much riskier than only being out of rhythm less than 1% of the time. And, as you might suspect, studies back this up. CHADS-VASc, however, doesn’t care. To the CHADS-VASc score, one brief minute of atrial fibrillation carries the same risk as one year of continuous atrial fibrillation.
13. It Rejects the Health of Your Left Atrium
When it comes to your atrial fibrillation stroke risk, the health of your left atrium also matters. For example, the more dilated your left atrium, the higher your stroke risk. Also, the more scar tissue you have in your left atrium also predicts your stroke risk. Once again, CHADS-VASc doesn’t care. A perfectly healthy left atrium is treated the same way as a massively dilated and scarred up left atrium.
Are there Any Better Scoring Systems?
Given the limitations of the CHADS-VASc scoring system, is there anything else out there? Yes, other scoring systems have been proposed. For example, there is the ABC-Stroke system which uses blood tests to help determine your stroke risk. Other scoring systems include GARFIELD-AF, ATRIA, and the Intermountain (my hospital) scoring system. None of these alternative scoring systems are perfect either. If nothing is perfect, what should you do?
The answer is to discuss this with your cardiologist. Only you and your physician can determine if blood thinners are right for you or not. And to make this decision, you have to take everything into consideration.
Avoid a Stroke…Read this Disclaimer
If you are on a blood thinner, don’t stop this drug based on anything you have read in this article. Also, don’t let anything I discussed in this article influence your decision. Strokes can happen and they usually happen in atrial fibrillation patients who are not taking blood thinners.
I have faith that you and your cardiologist can make the right decision for you. Because taking a blood thinner is a big decision, look at stroke risk factors beyond those of “CHADS-VASc.” And if you and your cardiologist do decide to hold off on blood thinners, then I would at least carefully check my pulse twice daily to make sure my heart was still in rhythm. If my heart ever did go out of rhythm, I would immediately get on a blood thinner.
Disclaimer Policy: This website is intended to give general information and does not provide medical advice. This website does not create a doctor-patient relationship between you and Dr. John Day. If you have a medical problem, immediately contact your healthcare provider. Information on this website is not intended to diagnose or treat any condition. Dr. John Day is not responsible for any losses, damages or claims that may result from your medical decisions.