Doctors & patients are saying about 'A-Fib.com'...


"A-Fib.com is a great web site for patients, that is unequaled by anything else out there."

Dr. Douglas L. Packer, MD, FHRS, Mayo Clinic, Rochester, MN

"Jill and I put you and your work in our prayers every night. What you do to help people through this [A-Fib] process is really incredible."

Jill and Steve Douglas, East Troy, WI 

“I really appreciate all the information on your website as it allows me to be a better informed patient and to know what questions to ask my EP. 

Faye Spencer, Boise, ID, April 2017

“I think your site has helped a lot of patients.”

Dr. Hugh G. Calkins, MD  Johns Hopkins,
Baltimore, MD


Doctors & patients are saying about 'Beat Your A-Fib'...


"If I had [your book] 10 years ago, it would have saved me 8 years of hell.”

Roy Salmon, Patient, A-Fib Free,
Adelaide, Australia

"This book is incredibly complete and easy-to-understand for anybody. I certainly recommend it for patients who want to know more about atrial fibrillation than what they will learn from doctors...."

Pierre Jaïs, M.D. Professor of Cardiology, Haut-Lévêque Hospital, Bordeaux, France

"Dear Steve, I saw a patient this morning with your book [in hand] and highlights throughout. She loves it and finds it very useful to help her in dealing with atrial fibrillation."

Dr. Wilber Su,
Cavanaugh Heart Center, 
Phoenix, AZ

"...masterful. You managed to combine an encyclopedic compilation of information with the simplicity of presentation that enhances the delivery of the information to the reader. This is not an easy thing to do, but you have been very, very successful at it."

Ira David Levin, heart patient, 
Rome, Italy

"Within the pages of Beat Your A-Fib, Dr. Steve Ryan, PhD, provides a comprehensive guide for persons seeking to find a cure for their Atrial Fibrillation."

Walter Kerwin, MD, Cedars-Sinai Medical Center, Los Angeles, CA


Magnesium IV to Stop A-Fib

We have long advocated the benefits of Magnesium for A-Fib. (See Magnesium Long-Life Insights for A-Fib Patients.)

Intravenous Delivery: A recent randomized controlled double-blind study found that Magnesium delivered directly into the bloodstream (Intravenous, i.e., IV) can produce both rate and rhythm control when used for A-Fib patients in the emergency room (ER).

The Good News: This study from the University of Monastir, Tunisia, found Magnesium IV is the fastest way to improve Magnesium levels and is very effective in restoring A-Fib patients to normal sinus rhythm.

The Bad News: In U.S. emergency rooms, Magnesium IV is not a standard treatment for A-Fib patients (though it may be used prior to cardioversion). (Dr. Julian Whitaker in Newport Beach, CA performs this therapy (www.drwhitaker.com).)

One of our Advisory Board members wrote me about his large facility’s experience with Magnesium IVs, “A few years ago we tried and stopped because of futility.”

Bottom Line: So it’s an interesting research study, but don’t look for a Magnesium IV if you end up in the ER with an A-Fib episode.

Resource for this article
Bouida, W. et al. Low-dose Magnesium Sulfate versus High Dose in the Early Management of Rapid Atrial Fibrillation: randomized controlled double-blind study. (LOMAGHI Study). Acad Emerg Medi. 2019;26(2):183-191. https://www.onlinelibrary.wiley.com/doi/full/10.1111/acem.13522 doi.org/10.1111/acem.13522

Original Medicare or Medicare Advantage Plans? Which is Better If You have A-Fib?

An A-Fib.com reader emailed me that he has A-Fib and is turning 65. He has to decide whether to sign up for Original Medicare or a Medicare Advantage plan. (Open Enrollment is between October and December each year). This decision will affect how much he pays for coverage, what services he gets, what doctors he can use, and his overall quality of care.

Medicare coverage options is a complicated business. I’m not qualified to give you advice. My intent is to point out areas of interest to A-Fib patients. Remember these comments are only my opinion.

Choice of Doctors?

Which is better if you have A-Fib?

With the Medicare Advantage plans, your choice of doctors is limited. Usually you can only use doctors in the plan’s network. This may be fine for a primary care doctor or family doctor.

What if you need a specialist? To see a specialist, you’ll need a referral from your primary care doctor. These referrals are often hard to obtain. You also need prior approval for most services.

Choice of Electrophysiologists (EPs)?

If you have A-Fib, your choice of EPs in Medicare Advantage plans is severely limited. All too often Medicare Advantage plan administrators seem more motivated to reduce your choices.

In one instance, I found only a single EP listed as available for someone I was trying to advise.

Referrals Out of Network. And it’s nearly impossible to get a referral to an industry leader, no matter how good a doctor is or how great a reputation they have. The administrators make it incredibly difficult. And there is usually no appeal.

Not All EPS Are Equal. Most EPs in Medicare Advantage plans would not be considered world beaters (i.e., best in their field). Though most of my experience with Advantage Plans is anecdotal, I’ve never seen an EP industry leader listed in these types of plans.

Not all EPs are equal. Some are low volume operators with high complication rates. You want to avoid these types of EPs at all costs.

When You Need the Best: If your A-Fib is difficult to treat or you have comorbidities (i.e., hypertension, obesity, diabetes) that complicate your treatment, your choice of EP is vital. You need an EP with a track record in successfully treating difficult A-Fib cases.

Shameful: I know of one person who was diagnosed with A-Fib under a Medicare Advantage plan. She was never told about Electrophysiologists who are specialists in arrhythmias, and she was never told about treatments like catheter ablation. This is all despite her facility having well-respected EPs and an active catheter ablation lab. The staff knew but didn’t discuss it with her.

In the end, she had to visit our website to learn about Electrophysiologists and catheter ablation options.

Medicare Gives You Real Choices

Compared to Medicare Advantage plans, with Original Medicare you can use any doctor or hospital that takes Medicare, anywhere in the US.

This is really important if you have A-Fib. You want to be able to go to the best EP you can find.

Fees or Fines for Seeing an EP in Medicare Advantage Plans

Another factor to be considered in Medicare Advantage plans is you pay a fee or fine for every time, for example, when you see an EP. One person told me his fee was $45.00 for one visit to an EP. Those fines or fees can add up pretty fast, especially when you have comorbidities and see multiple doctors for specialized tests.

In contrast, Original Medicare covers routine doctors’ visits. They send payment to the doctor, and the doctor cannot charge the person more than the plan allows. (Check your coverage before making any coverage decision.)

Be Prepared to Fight Advantage Plan Administrators

Having to interact with a Medicare Advantage plan administrator can be a very frustrating experience. Knowing you’re not being taken care of properly can be very depressing.

You often have to be very assertive and fight them ‘tooth and nail’ to get the care and treatment you need. It can take weeks, months, even years until you finally see the right doctors and receive the treatment you need.

Medicare: More Choices and Better for Psychological Health

The bottom line for most A-Fib patients is that Original Medicare not only gives you more choices but is also better for your psychological health. Also, with Original Medicare if you disagree with a coverage or payment decision, you have the right to appeal. (See Your Medicare Benefits booklet.)

Under Original Medicare, it’s tremendously liberating to know you can go to any doctor or facility you want. The last thing you want in your life is some bureaucrat dictating to you what treatments or doctors you can access.

Though obviously many personal and individual factors may influence your choice of Medicare plans, in general, Original Medicare is probably a better choice for many patients with A-Fib.

Medicare coverage options is a complicated business. To learn more, see the downloadable booklet, Your Medicare Benefits.

Are My Comments Too Negative?

Your choice of health coverage is a tricky subject. People tend to email me when they have negative experiences. So, my anecdotally-based comments may be more negative than warranted. There are many different Medicare Advantage plans. Some may be better than others.

If anyone has any clinical studies on this subject or more positive experiences, please let me know.

Cloud graphic - Michele Straube, A-Fib-free after 30 years - A=Fib.com

Side Effects of Flecainide: An A-Fib Patient’s Perspective

Carol, from Salem, Oregon, wrote me to share how taking the antiarrhythmic drug, flecainide, affected her.
Flecainide, an antiarrhythmic medication, works by slowing electrical signals in the heart to stabilize the heart rhythm.

“When I initially started taking flecainide for my A-Fib, I experienced annoying visual disturbances, especially when there was a difference between a light and dark environment such as a stage or when going from a light to a dark room. I would see afterimages, many of them. For example, in a theater I’d see my hands clapping, but I’d see many of them as if in a time lapse still photo. Over time that effect got better.

But other side effects developed.

…Here it goes again. I plan to call the Cardiologist as soon as the office opens. I have the following symptoms:

Irregular heartbeat
stomach discomfort (bloating)
rash and hives
hair loss
anxiety (my shoulders are practically making contact with my ears)
sleep problems
increased sweating
annoying visual disturbances

These are all listed on the package insert as possible side effects. 

Flecainide is pronounced as (flek’ a nide)

However, I am not ready to say they were caused by flecainide as I have had lifelong problems with allergies and digestive issues. Except for the visual disturbances…

I was on flecainide for 12 years―and it mostly worked well―until it didn’t anymore.”

Carol Baumann,
Salem, Oregon

Editor’s Comments

Editor's Comments about Cecelia's A-Fib story
One of the most frequently prescribed antiarrhythmic drugs is flecainide acetate (Tambocor). Flecainide has been around a long time (1985) and is only available as a generic drug.
Instead of a daily dose, fecainide can be used as a “Pill-In-The-Pocket” treatment i.e., taking an antiarrhythmic med at the time of an A-Fib attack.
Flecainide carries an FDA “Black Box Warning” which is the most serious the FDA issues. A Black Box Warning alerts doctors and patients that a drug has potentially dangerous effects.

Lookup fecainide at MedlinePlus.gov

As with almost all antiarrhythmic drugs, flecainide is known for bad side effects.
To read a detailed description of flecainide, its uses and side effects, see fecainide at MedlinePlus/Drugs, Herbs and Supplements (U.S. National Library of Medicine).

Don’t Want to Take Anticoagulants? Three Alternatives for A-Fib Patients

With Atrial Fibrillation, you are 4–5 times more likely to have an A-Fib (ischemic) stroke. Taking an anticoagulant helps prevent an A-Fib stroke and may give you peace of mind.

The negative side is that all anticoagulants are high-risk medications and inherently dangerous. You bruise easily, cuts take a long time to stop bleeding. You can’t participate in any contact sports. There is an increased risk of developing a hemorrhagic stroke and gastrointestinal bleeding. See Risks of Life-Long Anticoagulation.

Be advised that no anticoagulant or blood thinner will absolutely guarantee you will never have a stroke. Even warfarin [Coumadin] only reduces the risk of stroke by 55% to 65%.

(Most EPs are well aware of the risks of life-long anticoagulation.)

Don’t want to take anticoagulants? What’s the alternative? Remove the reason you need an anticoagulant!

Three Alternatives to Taking Anticoagulants

Anticoagulants are used with high-risk Atrial Fibrillation patients for the prevention of clots and stroke.

The best way to deal with the increased risk of stroke and side effects of anticoagulants is to no longer need them. Here are three options:

RF Catheter ablation

#1 Alternative: Get rid of your A-Fib.

As electrophysiologist (EP) and prolific blogger Dr. John Mandrola wrote: “…if there is no A-Fib, there is no benefit from anticoagulation.”

Action: Request a catheter ablation procedure. Today, you can have an ablation immediately (called ‘first-line therapy’). You don’t have to waste a year on failed drug therapies. See Catheter Ablation Reduces Stroke Risk Even for Higher Risk Patients

Placing Watchman in LAA

#2 Alternative: Close off your Left Atrial Appendage (LAA).

The Left Atrial Appendage is where 90%-95% of A-Fib clots originate. Closing off the LAA provides similar protection against having an A-Fib (ischemic) stroke as being on an anticoagulant.

Action: Request a Watchman device. The Watchman device is inserted to close off your LAA and keep clots from entering your blood stream. See Watchman Better Than Lifetime on Warfarin

Natural blood thinners

#3 Alternative: Consider non-prescription blood thinners

Perhaps you can benefit from an increase in natural blood thinners such as turmeric, ginger and vitamin E or, especially, the supplement Nattokinase.

Action: Ask your doctor about your CHA2DS2-VASc score (a stroke risk assessor). If your score is a 1 or 2 (out of 10), ask if you could take a non-prescription approach to a blood thinner. See FAQ: “Are natural blood thinners as good as prescription blood thinners?” 

If you decide to take an DOAC, ask your doctor about taking Eliquis. It tested better than the other DOACs and is considered safer. 

Bottom Line

Whether or not to take anticoagulants (and which one) is one of the most difficult decisions you and your doctor must make. To stop taking an anticoagulant, talk to your doctor about alternatives:

• Catheter ablation
• LAA closure (Watchman device)
• Non-prescription blood thinners

These options may help you to no longer need an anticoagulant. As Dr. John Mandrola wrote: “…if there is no A-Fib, there is no benefit from anticoagulation.”

As an A-Fib patient, don’t settle for a lifetime on anticoagulants or blood thinners. Remember: You must be your own best patient advocate.

Resource for this article
Weng Y, et al. Nattokinase: An Oral Antithrombotic Agent for the Prevention of Cardiovascular Disease. Int J Mol Sci. 2017;18(3):523. Published 2017 Feb 28. doi:10.3390/ijms18030523

Who’s at Higher Risk of a Recurrent A-Fib Stroke?

You’ve had an A-Fib stroke—and you survived—hoorah! Now you wonder…am I more prone to a recurrent stroke? The answer may lie with how often your A-Fib episodes occur (i.e., paroxysmal versus persistent/permanent).

A recent observational research study from Japan posed this question:

In patients with a history of ischemic stroke and atrial fibrillation (A-Fib), is there a difference in the risk of future stroke between those with paroxysmal versus permanent atrial fibrillation?

What’s the Risk of a Recurrent A-Fib Stroke?

The SAMURAI-NVAF study included 1,192 A-Fib patients who had suffered an acute or ischemic stroke (where a clot blocks blood flow to the brain) and followed them for around 1.8 years.

Study patients were hospitalized within 7 days of stroke between April 2011 and March 2014 at 18 Japanese stroke centers. The average age was 77.7 ± 9.9 years, 44% were women, and 63.6% had persistent A-Fib.

Findings: Patients with Persistent A-Fib at Higher Risk of Recurrent Stroke

The researchers found a higher risk of ischemic stroke (or systemic embolism) in those with persistent A-Fib. Persistent patients also had higher rates of both ischemic strokes and transient ischemic attacks (TIAs).

Comorbidities means presence of two or more diseases or medical conditions in a patient.

Patients with persistent A-Fib were in general less healthy. They were more likely to have comorbidities: congestive heart failure, liver problems, higher alcohol use, and more disability after the first stroke.

Patients with paroxysmal A-Fib were associated with increased odds of “functional independence” 3 months after their A-Fib stroke (i.e., less likely to be disabled after the stroke).

Why More Stroke Risk When Persistent? The researchers noted that patients with persistent A-Fib have larger Left Atrial Appendage (LAA) size and more severe blood flow problems (lower LAA ejection fraction). … Continue reading this report…->

Unsafe Interaction Between Pradaxa and Common Calcium Channel Blockers

An observational study published in 2020 found that people with A-Fib taking two common rate control calcium channel blockers along with the anticoagulant Pradaxa had higher bleeding rates (GI bleeding, minor bleeding, and minor GI bleeding).

The study was an analysis of the potential drug-drug interaction between verapamil or diltiazem and DOACs.

The term DOAC has replaced use of NOAC.

The study was conducted using US population-based data (2010-2015) analyzed between January 1 and July 15, 2019. Data were obtained on 48,442 patients with nonvalvular atrial fibrillation who had received an index prescription of dabigatran, rivaroxaban, or apixaban.

Analysis was restricted to individuals with no history of kidney disease who were receiving standard doses of the DOACs.

Drug-Drug Interactions Found When Co-Administered

Researchers found that taking the drugs Verapamil and Diltiazem (rate control calcium channel blockers) along with the anticoagulant Pradaxa had higher bleeding rates.

Other anticoagulants such as Xarelto and Eliquis didn’t cause more bleeding. (Apixaban [Eliquis] had consistently lower bleeding event rates among all DOACs.)

(For you technical types, Dabigatran functions as a P-glycoprotein inhibitor (P-gp), an important protein that pumps many foreign substances, such as toxins and drugs, out of cells. Verapamil and diltiazem are also P-gp inhibitors.)

Pradaxa Data Compiled and Compared to Four Calcium Channel Blockers

The investigators compiled data from IBM Watson MarketScan Databases.

Comparisons were made between 1,764 Pradaxa (dabigatran etexilate) users taking verapamil or diltiazem versus 3,105 Pradaxa users taking amlodipine (a calcium channel blocker used primarily to lower blood pressure which isn’t a P-gp inhibitor). The overall bleeding rate was 52% higher compared to amlodipine.

In addition, comparisons were made between 1,793 Pradaxa users taking verapamil or diltiazem versus 3,224 Pradaxa users on metoprolol (a beta-blocker which isn’t a P-gp inhibitor). The overall bleeding rate was 43% higher compared to metoprolol.

Avoid Mixing Pradaxa with Verapamil & Diltiazem

The message of this study is clear. “Clinicians and patients may need to consider alternative DOAC therapy other than dabigatran” when using P-gp inhibitors such as verapamil and diltiazem. (Amiodarone is another P-gp inhibitor.) “It is not safe to combine dabigatran (Pradaxa) with P-glycoprotein (P-gp) inhibitors in people with atrial fibrillation (Afib)” regardless of kidney function.

What This Means to Patients

If you are taking the anticoagulant Pradaxa, along with Verapamil and Diltiazem (rate control calcium channel blockers), talk to your doctor about changing to another DOAC (and take a copy of this article with you).

Happily, there are several DOACs, so there’s seldom an overwhelming need to continue on Pradaxa (dabigatran). Eliquis (apixaban), for example, tested the best and is the safest of the DOACs.

Resources for this article
• Lou, Nicole. An Unsafe Interaction Between Pradaxa and Common Meds―Study suggests drug-drug interaction regardless of kidney function. Medpage Today, April 24, 2020. https://www.medpagetoday.com/cardiology/prevention/86132

• Pham, P. et al. Association of oral anticoagulants and verapamil or diltiazem with adverse bleeding events in patients with nonvalvular atrial fibrillation and normal kidney function. JAMA Network Open, 2020; 3(4): e203593. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2764843

Book Review: “Restart Your Heart: The Playbook for Thriving with AFib” by Dr. Aseem Desai

Review by Steve S. Ryan, PhD

Restart Your Heart by Dr. Aseem Desai

Dr. Aseem Desai’s book Restart Your Heart: The Playbook for Thriving with AFib is written for Atrial Fibrillation patients by a practicing Electrophysiologist. It will be well received and is long overdue.

Caveat: By advocating living with A-Fib and by not telling patients of the dangers of living in A-Fib, Dr. Desai may be doing lasting harm to many A-Fib patients.

Dr. Desai’s Writing Style

One of the best features of Dr. Desai’s book is his patient-friendly writing style. He avoids “medicalize.” What he writes is easy to read and relatable. And he doesn’t shy away from explaining complicated concepts.

He is particularly good at explaining the scientific basis of A-Fib in a way patients can relate to. In particular, his explanation and illustration of Ion Channel Receptors (p. 21-23) is one of the best parts of his book.

A Dangerous and Deceptive Goal for A-Fib Patients

Atrial Fibrillation (A-Fib) is a progressive disease. The longer you have A-Fib, the greater the risk of your A-Fib episodes becoming more frequent and longer, often leading to continuous (Chronic) A-Fib. The abnormal rhythm in your heart causes changes and enlarges your atria (called remodeling), making it work harder over time.

Leaving patients in A-Fib overworks the heart, leads to fibrosis, stretches/expands the atrial heart walls, weakens the heart, increases the risk of  stroke, develops (congestive) heart failure, and leads to dementia because of reduced blood flow to the brain.

I cannot endorse Dr. Aseem Desai’s book because he encourages patients to live with A-Fib. He writes/advocates the following (location noted):
… Continue reading this book review..->

Gastroparesis: a Rare Complication After A-Fib Ablation

Gastroparesis is a condition in which your stomach empties into your small intestine more slowly than it should. It can be either temporary or chronic. Gastroparesis can occur after surgery or another medical procedure that interrupts your digestion.

Symptoms of Gastroparesis

When you have Gastroparesis, you feel bloated after eating, you may have stomach pain, or you may be vomiting. You may lose weight, your blood sugar levels may fluctuate, you may be dehydrated, your esophagus may be inflamed and you may experience malnutrition because your stomach isn’t absorbing nutrients.

Gastroparesis After Catheter Ablation

Gastroparesis is a rare complication of A-Fib ablation. It’s a condition that affects the stomach muscles and prevents proper stomach emptying. If after your catheter ablation, you experience any of the above symptoms, you may be experiencing Gastroparesis.

The cause can be damage to the vagal nerve which controls the stomach muscles. This can happen when ablation at the right inferior Pulmonary Vein (PV) affects the esophagus. The distance between the right inferior PV (RIPV) and the esophagus is an independent predictor of gastroparesis. … Continue reading this report…->

Are Women at Higher Risk of Dementia? A Rotterdam Observational Study

Background: The Rotterdam Study is a population-based study ongoing since 1990 in the city of Rotterdam in The Netherlands. It was a response to the changing demographics leading to an increase of elderly in most populations. Follow-up studies have been effective in finding causes of heart disease and cancer.

Dementia risk is increasing worldwide. An observational population-based study from Rotterdam found that there was a higher risk of dementia in Dutch women versus men (25.9% vs 13.7%). Rates of stroke were similar between women and men. The women had a higher lifetime risk of developing dementia (1 in 3 for women vs 1 in 5 for men).

Is Greater Life Expectancy a Factor?

One can’t help but wonder why these Dutch women had an increased risk of developing dementia as compared to risk of stroke.

The authors of this study speculated that this discrepancy may be due to the fact that women in the Rotterdam study had a higher life-expectancy than men (83.5 years vs 81.7 years for men).

“With longer life-expectancy, individuals (women) in this study simply had more time to develop (dementia) in a timeframe with high age-specific incidence rates.”

The authors also pointed out that the women in this study “were substantially lower educated compared to men, which may have led to a lower dementia resilience in women.”

Gender-Specific Interventions to Reduce Risk of Dementia

Unfortunately, there aren’t any medicines that can cure dementia or slow it down. But there are treatments to help ease some of its symptoms.

The good news: In high income countries, there is a declining number of people developing dementia. This may be due to preventive strategies such as better vascular risk factor management, improved educational attainment, and other public health developments that improve the resilience for dementia.

The authors recommend gender-specific interventions to help reduce the risk of dementia. For example, support for women suffering from loneliness and depression and dietary counseling for men.

Editor’s Comments
Editor's Comments about Cecelia's A-Fib story
Developing Dementia is Related to Aging Not Gender: This observational study does not imply that women are genetically inferior to men with regard to the risk of developing dementia. Developing dementia is related to aging, and women, in general, do live longer than men.
Loneliness and Depression Risk Factors for Dementia: I correspond with a woman with A-Fib who recently lost her husband. He died way too young. She is still devastated by the loss.
It happens all too often. Women out living their husband/life companion of many years.

Though a non-genetic factor, loneliness and depression certainly are risk factors for dementia. As a society we need to recognize what many older women experience and offer support.

Resources for this article
• Licher, S. et al. Lifetime risk of common neurological diseases in the elderly population. J Neurol Neurosung Psychiatry. 2019;90:148-156. https://jnnp.bmj.com/content/90/2/148 . doi: 10.1136/jnnp-2018-318650.

• Bunch, T. Jared. Cognitive Decline and Dementia in Patients with Atrial Fibrillation: Update on the CAF and PLUG Dementia Trials. EP Lab Digest. January 2020, vol. 20, no 1. P. 1.

How Long Does It Take for an A-Fib Clot to Form? The ASSERT Clinical Trial

Background: Of A-Fib stroke patients, 23% die and 44% suffer significant neurologic damage. This compares to only an 8% mortality rate from other causes of stroke.

How Long Does It Take for a Clot to Form? Some doctors say it only takes around 5 minutes for an A-Fib clot to form and cause a stroke that kills you.

This is generally not accepted thinking among Cardiologists and Electrophysiologists (EPs). The ASSERT clinical trial gives us some insights.

How Do Clots Form and Cause Strokes?

Clots aren’t formed instantaneously. It takes a while for blood to pool and form a clot of significant size. If you have a ten-minute attack of A-Fib, for example, it’s unlikely a clot/stroke will develop.

When someone is in A-Fib, blood is not being effectively pumped out of the left atrium. There are spots where blood can pool such in as the Left Atrial Appendage (LAA). This pooled blood can form a clot.

When the left atrium again beats normally, it can push this clot downstream into the left ventricle and into the bloodstream. From there, the clot can travel into the brain causing an ischemic (blocking) stroke.

Patients in permanent A-Fib are at higher risk of clots and stroke. But not in just a few minutes.

(Another risk of A-Fib is a hemorrhagic stroke when a blood vessel bursts, causing bleeding in the brain.)

ASSERT stands for “Asymptomatic Atrial Fibrillation and Stroke Evaluation in Pacemaker Patients and the Atrial Fibrillation Reduction Atrial Pacing Trial”.

The ASSERT Study

The ASSERT clinical trial is a fascinating study with data collected by pacemakers and defibrillators (ICDs). Researchers looked at pacemaker patients and their risks of developing Silent A-Fib and stroke. Their primary question was: Do Pacemakers Prevent A-Fib?

A secondary benefit of the study is the A-Fib patient data collected. In particular, when and how long it takes for A-Fib patients to develop a serious risk of stroke.

The study gives us insight into when and how long it takes for A-Fib patients to develop a serious risk of stroke.

Study Description: The ASSERT study enrolled 2,580 patients, 65 years of age or older, with hypertension and no history of A-Fib, in whom a pacemaker or defibrillator (ICD) had recently been installed.

The pacemaker and ICD devices were programmed to detect silent A-Fib (i.e., Subclinical Atrial Tachycardia [SCAF]) when the heart rate reached 190 beats or more per minute lasting more than 6 minutes. The devices were checked at a clinical visit 3 months later. These patients were then followed up for around 2.5 years.

How Long in Silent A-Fib to Significantly Increase Clot/Stroke Risk

In the ASSERT study they found that it took more than 17.72 hours to significantly increase the annual stroke risk. The results of all patients are divided into four quartiles:

Duration Quartile: Time in Silent A-FibAnnual Stroke Risk
≥ 0.86 Hours1.23 %
0.87-3.63 Hours0 %
3.64-17.72 Hours1.18 %
˃ 17.72 Hours4.89 %

Researchers found the annual stroke risks are similar to the stroke risk for healthy people (which is considered to be 1%).

The ASSERT study basically said that it takes around 24 hours of silent A-Fib to develop a serious clot/risk of stroke (on average 3.1%).

Contrary Interpretation: In a later analysis of the same ASSERT study by Van Gelder (2017), patients with lengths of Subclinical Atrial Tachycardia (SCAF) from 6hrs to 24hrs were not significantly different from patients without SCAF.

Similar Trial Results: The TRENDS study, a prospective, observational study, also used implanted devices and found similar results as the ASSERT study.

Do Pacemakers Work to Prevent A-Fib?

The primary question of the ASSERT study was: Do Pacemakers Prevent A-Fib?
Finding: Pacemakers (continuous overdrive pacing) “does not prevent clinical atrial fibrillation.”

Editor’s Comments

Editor's Comments about Cecelia's A-Fib storyShorter Episodes of A-Fib Not Generally Dangerous: Despite studies such and ASSERT and TRENDS, we still need many more studies on how long it takes for a clot/stroke to form. Probably the most useful data to date does come from the ASSERT study where it took around 24 hours of silent A-Fib before clot/stroke risk was significantly increased.
People with shorter episodes of A-Fib or silent A-Fib, such as may occur after a successful catheter ablation, may not need to be on anticoagulants at all. Remember that anticoagulants are high risk drugs that shouldn’t be taken unless there is a real risk of stroke.

The general consensus is that A-Fib clots/strokes take around 24 hours to develop. In a popular article in Bottom Line Health, Dr. Antonio Gotto, cardiovascular disease specialist at Weill Cornell Medical College in New York City, says it takes one day for a clot to form.

Resources for this article

• Healey, J.S. et al. Subclinical Atrial Fibrillation and the Risk of Stroke. The New England Journal of Medicine 2012; 366:120-129. http://www.nejm.org/doi/full/10.1056/NEJMoa1105575?viewType=Print&viewClass=Print# DOI: 10.1056/NEJMoa1105575

• Glotzer, T. V. et al. The Relationship Between Daily Atrial Tachyarrhythmia Burden From Implantable Device Diagnostics and Stroke Risk―The TRENDS Study. Circulation: Arrhythmia and Electrophysiology, August 4, 2009. 2009;2:474-480. https://www.ncbi.nlm.nih.gov/pubmed/19843914 doi: 10.1161/CIRCEP.109.849638

• Gotto, Jr., Antonio M. Bottom Line Health, Vol 26, November 2012, p. 4.

• Van Gelder, I.C. et al. Duration of device-detected subclinical atrial fibrillation and occurrence of stroke in ASSERT. European Heart Journal, Volume 38, Issue 17. 1 May 2017, Pages 1339-1344, https://academic.oup.com/eurheartj/article/38/17/1339/3059370. doi.org/10.1093/eurheartj/ehx042

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