ABOUT 'BEAT YOUR A-FIB'...


"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

"Your book [Beat Your A-Fib] is the quintessential most important guide not only for the individual experiencing atrial fibrillation and his family, but also for primary physicians, and cardiologists."

Jane-Alexandra Krehbiel, nurse, blogger and author "Rational Preparedness: A Primer to Preparedness"



ABOUT A-FIB.COM...


"Steve Ryan's summaries of the Boston A-Fib Symposium are terrific. Steve has the ability to synthesize and communicate accurately in clear and simple terms the essence of complex subjects. This is an exceptional skill and a great service to patients with atrial fibrillation."

Dr. Jeremy Ruskin of Mass. General Hospital and Harvard Medical School

"I love your [A-fib.com] website, Patti and Steve! An excellent resource for anybody seeking credible science on atrial fibrillation plus compelling real-life stories from others living with A-Fib. Congratulations…"

Carolyn Thomas, blogger and heart attack survivor; MyHeartSisters.org

"Steve, your website was so helpful. Thank you! After two ablations I am now A-fib free. You are a great help to a lot of people, keep up the good work."

Terry Traver, former A-Fib patient

"If you want to do some research on AF go to A-Fib.com by Steve Ryan, this site was a big help to me, and helped me be free of AF."

Roy Salmon Patient, A-Fib Free; pacemakerclub.com, Sept. 2013


Paroxysmal

A-Fib Non-PV Triggers Predict Need for Multiple Ablations

Could the necessity for multiple ablation procedures be predicted? According to a new research study, the answer is YES!

In a study of patients who had catheter ablation of the Pulmonary Veins (PVs) for paroxysmal (occasional) A-Fib, 8% had to have more than two ablations to be A-Fib free.

The only independent predictor of the need for multiple procedures was the presence of non-PV triggers. According to this research, EPs should check for non-PV triggers such as at the ligament of Marshall.

This 2015 published study was done before the widespread use of Contact Force sensing catheters which seem to have reduced recurrence and the need for multiple ablation procedures.

What This Means to Patients

The lesson to be learned from this study: When having an ablation, make sure your Electrophysiologist (EP) is experienced at tracking down (mapping) and ablating (isolating) non-PV triggers.

For example, I recently read an O.R. (Operating Room) report of a patient who, after isolating the PVs, was still in A-Fib. Instead of looking for non-PV triggers, the EP just electrocardioverted the patient back into sinus rhythm. This does sometimes work. But not in this case. The ablation failed.

This is particularly important for EPs doing CryoBalloon ablations.

Arctic Cryoballoon Catheter

Arctic Cryoballoon Catheter

Find EPs Experienced at Ablating Non-PV Triggers

When getting a CryoBalloon ablation, you need to find an EP who is willing to do more than just isolate your PVs—someone who will put out the extra effort to find and ablate non-PV triggers such as at the ligament of Marshall.

To do this, your EP may have to replace the CryoBalloon catheter with an RF catheter to ablate these non-PV triggers. This may require mapping and ablation skills not all EPs have.

What to Ask Prospective EPs

To find the right EP for your CryoBalloon ablation ask:

What do you do if I’m still in A-Fib after you do the CryoBalloon ablation?

(You want to hear they’ll search for and ablate non-PV triggers.)

For more about Ablating Non-PV Triggers, see my article: CryoBalloon Ablation Study: 30% of Patients Required RF to Achieve Isolation

See the glossary for Ligament of Marshall.

References for this article

New FAQ: Is Having an ablation Better Than Living in Paroxysmal A-Fib?

“In one of your articles it said that having an ablation was better than living in A-Fib. I’ve been taking 75 mg of propafenone 3X/day for seven years and have only had 5 A-Fib attacks in 7 years. If your article means Paroxysmal too, then I will consider an ablation.”

Five A-Fib attacks in seven years is very few. With paroxysmal A-Fib like yours, most doctors would say to continue on propafenone till you start having more or longer A-Fib attacks. (As a point of reference, about 54% of those in paroxysmal A-Fib will go into permanent A-Fib within one year. You’ve made it 7 years!) You aren’t really “living in A-Fib.” The antiarrhythmic drug you’re taking is fairly successful in keeping you out of A-Fib.

A-Fib is a progressive disease that tends to get worse over time. So, consider this. By the time propafenone loses its effectiveness (which is probably inevitable), how permanently damaged will your heart be? How much will your A-Fib have progressed? Will your A-Fib be harder to cure than if you had had a catheter ablation earlier? …. Read the two steps Steve recommends to this reader->

 

FAQs Coping with A-Fib: Living in A-Fib vs. Ablation

 FAQs Coping with A-Fib: Living in A-Fib

FAQs A-Fib afib20. “In one of your articles it said that having an ablation was better than living in A-Fib.  I’m 73 years old and have Paroxysmal A-Fib. I’ve been taking 75 mg of propafenone 3X/day for seven years and have only had 5 A-Fib attacks in 7 years. If your article means all types of A-Fib including Paroxysmal, then I will consider an ablation.”

You really aren’t living in A-Fib. You’re taking an antiarrhythmic treatment meant to stop or limit your A-Fib. (Unlike rate-control drugs which only try to limit or control heart rate while leaving you in A-Fib.) For now it’s working fairly well for you.

Drug therapy tends to become ineffective or stop working over time.

Five A-Fib attacks in seven years is very few. With paroxysmal A-Fib like yours, most doctors would say to continue on propafenone till you start having more or longer A-Fib attacks.

(As a point of reference, about 54% of those in paroxysmal A-Fib will go into permanent A-Fib within one year. You’ve made it 7 years!)

A-Fib is a progressive disease that tends to get worse over time.

Consider this. By the time propafenone loses its effectiveness (which is probably inevitable), how permanently damaged will your heart be? How much will your A-Fib have progressed? Will your A-Fib be harder to cure than if you had had a catheter ablation earlier? 

For future reference, you need to know the physical diameter or stretching of your left atrium.

What to Do Now

You need to know the physical diameter or stretching of your left atrium. Electrophysiologists normally perform this measurement when giving patients a stress and Echo test.

For your own records, you should get the actual physical diameter measurement in mm or cm and/or the volume of your left atrium. Don’t settle for words like “mildly dilated” or “normal.” You want a benchmark measurement to compare to in the future.

Check for “silent” no-symptom A-Fib which you aren’t aware of. ‘Silent A-Fib’ is common. Up to 30%−50% of A-Fib patients are unaware they have A-Fib, often only learning about their Atrial Fibrillation during a routine EKG in their doctor’s office. 

Ask your doctor to check for ‘Silent A-Fib’ because it puts you at risk for blood clots and stroke.

Any type of longer-term monitoring (such as a Zio patch which you wear like a Band-Aid for 1-2 weeks or the Reveal Insertable Cardiac Monitor which is inserted just under your skin) could give you this info.

It’s important to know if you have ‘Silent A-Fib’ because it puts you at risk for blood clots and stroke.

The Bottom Line. Propafenone may be just prolonging the inevitable. Since you now have very few A-Fib attacks, you would probably be a relatively easy fix with a catheter ablation.

On the other hand, you may be one of the fortunate few who will never progress into more serious A-Fib. Everybody’s A-Fib is unique.

See 2015 AF Symposium: Living in A-Fib More Dangerous Than Having an Ablation. Thanks to Thomas Scheben for this question.

Last updated: Friday, August 7, 2015

Back to FAQs: Coping with Your A-Fib

FAQs A-Fib Treatments: Catheter Ablation Procedures

Catheter ablation illustration at A-Fib.com

Catheter ablation

Atrial Fibrillation patients seeking a cure and relief from their symptoms often have many questions about catheter ablation procedures. Here are answers to the most frequently asked questions by patients and their families. (Click on the question to jump to the answer)

1. “I have a defective Mitral Valve? Is it causing my A-Fib? Should I have my Mitral Valve fixed first before I have a PVA?

2. “With the recent improvements in Pulmonary Vein ablation techniques, should I wait for a better technique? I’m getting by with my Atrial Fibrillation.”

3. “Are there different types of “Pulmonary Vein Ablation”? Are they different from “Pulmonary Vein Isolation?

4. I’’ve heard of Cryo (freezing) catheters for PVA(I) ablations. Are they good or better than the RF (Radio Frequency) catheters for ablations?

5. “How dangerous is a Pulmonary Vein Ablation procedure? What are my risks?

6. “During the ablation procedure A-Fib doctors actually burn within the heart with RF energy. How does this burning and scarring affect how the heart functions? Should athletes, for example, be concerned that their heart won’t function as well after an ablation?

7. “How dangerous is the fluoroscopy radiation during an ablation? I know I need a Pulmonary Vein Ablation (Isolation) procedure to stop my A-Fib—A-Fib destroys my life. I can’t work or exercise, and live in fear of the next attack. Antiarrhythmic meds cause me bad side effects. But I’m worried about being exposed to radiation during the ablation.

8. “I have serious heart problems and chronic heart disease along with Atrial Fibrillation. Would a Pulmonary Vein Ablation help me? Should I get one?

9. “What is an enlarged heart? Does it cause A-Fib?. I was told I can’t have a Pulmonary Vein Ablation (Isolation) procedure because I have an enlarged heart. Why is that?”

10. “I am 82 years old. Am I too old to have a successful Pulmonary Vein Ablation? What doctors or medical centers perform PVAs on patients my age?

11. “Since my PVI, I have been A-Fib free with no symptoms for 32 months. What do you think my chances of staying A-Fib free are?”

12. “How long before you know a Pulmonary Vein Ablation procedure is a success? I just had a PVA(I). I’ve got bruising on my leg, my chest hurts, and I have a fever at night. I still don’t feel quite right. Is this normal?”

13. I want to read exactly what was done during my Pulmonary Vein Ablation. Where can I get the specifics? What records are kept?

14. “What is the typical length of a catheter ablation today versus when you had your catheter ablation in 1998 in Bordeaux, France? What makes it possible?

15. “After my successful Pulmonary Vein Ablation, do I still need to be on blood thinners like Coumadin or aspirin?

16. “I’ve had a successful ablation. For protection against potential stroke risk if my A-Fib re-occurs, which if better—81 mg baby aspirin or 325 mg?

17. Since my ablation, my A-Fib feels worse and is more frequent than before, though I do seem to be improving each week. My doctor said I shouldn’t worry, that this is normal. Is my ablation a failure?

18. “I love to exercise and I’m having a PVA. Everything I read says ‘You can resume normal activity in a few days.’ Can I return to what’s ‘normal’ exercise for me?

19. I have Chronic Atrial Fibrillation (the heart remains in A-Fib all the time). Am I a candidate for a Pulmonary Vein Ablation? Will it cure me? What are my chances of being cured compared to someone with Paroxysmal (occasional) A-Fib?

20. “I’m 80 and have been in Chronic (persistent/permanent) A-Fib for 3 years. I actually feel somewhat better now than when I had occasional (Paroxysmal) A-Fib. Is it worth trying to get an ablation?

21.“Will an ablation take care of both A-Fib and Flutter? Does one cause the other? Which comes first A-Fib or Flutter?

22. Are there other areas besides the pulmonary veins with the potential to turn into A-Fib hot spots? I had a successful catheter ablation and feel great. Could they eventually be turned on and put me back into A-Fib

23. “During an ablation, how much danger is there of developing a clot? What are the odds? How can these clots be prevented?

24. “I was told that I will have to take an anticoagulant for about 2-3 months after my ablation. After all, if fibrillation episodes are reduced or eliminated after an ablation, shouldn’t there be even less need for a prescription anticoagulant rather than more?

25. “I’m six months post CryoBalloon ablation and very pleased. But my resting heart rate remains higher in the low 80s. Why? I’ve been told it’s not a problem. I’m 64 and exercise okay, but I’ve had to drop interval training.”

26. “I’ve heard good things about the French Bordeaux group. Didn’t Prof. Michel Häissaguerre invent catheter ablation for A-Fib? Where can I get more info about them? How much does it cost to go there?

27. “I’m a life-long runner. I recently got intermittent A-Fib. Does ablation (whether RF or Cryo) affect the heart’s blood pumping output potential because of the destruction of cardiac tissue? And if so, how much? One doc said it does.

Last updated: Thursday, September 8, 2016

Return to FAQs

FAQs Understanding A-Fib: Questions from Patients

FAQs Understanding Your A-Fib A-Fib.comFAQs: Understanding Atrial Fibrillation

Atrial Fibrillation patients often have loads of “Why?” and “How?” questions. Here are answers to the most frequently asked questions by patients and their families. (Click on the question to jump to the answer.)

1. Why does so much Atrial Fibrillation come from the Pulmonary Vein openings?

2. Is my Atrial Fibrillation genetic? Will my children get A-Fib too? Updated!

3. Why do older people get Atrial Fibrillation more than younger people?

4. Is Atrial Fibrillation (A-Fib) different from what doctors call Paroxysmal Supraventricular Tachycardia?

5. What is the difference between “Adrenergic” and “Vagal” Atrial Fibrillation? How can I tell if I have one or the other? Does it really matter? Does Pulmonary Vein Ablation (Isolation) work for Adrenergic and/or Vagal A-Fib?

6. What causes Paroxysmal (occasional) A-Fib to turn into Persistent (Chronic) A-Fib?

7. I’ve heard about ‘stiff heart’ or diastolic dysfunction. When you have A-Fib, do you automatically have diastolic heart failure? What exactly is diastolic dysfunction?

8. A-Fib and Flutter—I have both. Does one cause the other?” 

9. “My surgeon wants to close off my LAA during my Mini-Maze surgery. Should I agree? What’s the role of the Left Atrial Appendage?” 

10. “I’ve read about stem cells research to regenerate damaged heart tissue. Could this help cure A-Fib patients?”

11. What is the heart’s ejection fraction? As an A-Fib patient, is it important to know my EF? 

12. “I read that the local anesthesia my dentist uses may trigger my A-Fib. Why is that?”

13. “How can I determine or measure how much fibrosis I have? Can something non-invasive like a CT scan measure fibrosis?

14. “I have paroxysmal A-Fib with “pauses” at the end of an event. Will they stop if my A-Fib is cured? My cardiologist recommends a pacemaker. I am willing, but want to learn more about these pauses first.” NEW!

15. I have paroxysmal A-Fib and would like to know your opinion on which procedure has the best cure rate. NEW!

Last updated: Monday, August 8, 2016

Return to Frequently Asked Questions: Coping with A-Fib

FAQs Understanding A-Fib: Supraventricular Tachycardia

 FAQs Understanding A-Fib: Supraventricular Tachcardia

FAQs Understanding Your A-Fib A-Fib.com4. “Is Atrial Fibrillation different from what doctors call Paroxysmal Supraventricular Tachycardia?”

‘Supraventricular’ refers to the upper part of the heart, the atria. “Tachycardia” means the upper part of your heart is beating faster than normal. “Paroxysmal” means occasional.

“Supraventricular Tachycardia” in clinical practice commonly refers to atrial tachycardia, atrioventricular nodal reentrant tachycardia (AVNRT). Atrioventricular reciprocating tachycardia (AVRT), an entity that includes Wolff-Parkinson-White syndrome. While Atrial Fibrillation is a distinct entity classified separately.

The term “Supraventricular Arrhythmia” most often is used to refer to Supraventricular Tachycardias and Atrial Flutter. In practice, “Supraventricular Tachycardia” is often used loosely to include all arrhythmias in the Atria, including A-Fib.

Thanks to Sol Yuyitung for this question.

Go back to FAQ Understanding A-Fib

FAQs Understanding A-Fib: Paroxysmal to Persistent A-Fib, What Causes the Progression?

 FAQs Understanding A-Fib: Paroxysmal to Chronic

FAQs Understanding Your A-Fib A-Fib.com6. What causes Paroxysmal (occasional) A-Fib to turn into Persistent (chronic) A-Fib?

Researchers are still working to find the answer(s) to this question. We do know that some patients remain paroxysmal (usually with anti-arrhythmic therapy), while a large proportion progress to persistent A-Fib. (In a study of 5,000+ A-Fib patients, 54% of those on rate control meds went into permanent A-Fib in one year.)

The main trigger seems to be increased pressures in the left atrium that causes the muscle fibers around the pulmonary vein openings to start beating on their own.

Uncontrolled blood pressure, untreated sleep apnea and diabetes, or a worsening cardiomyopathy seem to be key factors that make people progress from Paroxysmal to Persistent A-Fib. Research tells us that even after a successful ablation for Persistent A-Fib, “the long term success rates depend mostly on treatment of hypertension and obstructive sleep apnea.”

What does this mean to you? The longer you have Atrial Fibrillation, the harder it can be to cure it. Consider working aggressively to stop your A-Fib as with antiarrhythmic meds or with a minimally-invasive Pulmonary Vein Ablation or a Mini-maze surgery. You don’t want to be part of the 54% whose A-Fib becomes permanent.

Go back to FAQ Understanding A-Fib

Catheter Ablation as Recommended First Choice – 2014 Boston AF Symposium

Dr. Hugh Calkins, Johns Hopkins Medical Center

Dr. Hugh Calkins

2014 Boston AF Symposium

Catheter Ablation as Recommended First Choice

Report by Dr. Steve S. Ryan, PhD, August 26, 2014

Dr. Hugh Calkins from Johns Hopkins gave a presentation entitled “Indications for AF Ablation: Guidelines vs. Clinical Reality.”

To begin his presentation, Dr. Calkins asked the Symposium attendees:

“Which statement correctly reflects your current approach to AF ablation as first line therapy in patients with symptomatic paroxysmal AF?”

•  I rarely recommend AF ablation as first line therapy in this patient group.

•  I routinely recommend AF ablation as first line therapy in this patient group.

Response: 79% of the attendees selected choice #1 {They used an electronic polling system placed at each seat.]

CURRENT GUIDELINES

According to the 2012 Guidelines (ESC Focused Update)1:

“Symptomatic AF refractory or intolerant to at least one Class 2 or 3 antiarrhythmic medication, catheter ablation is recommended.” With the following footnote: “Catheter ablation of symptomatic AF is considered a Class 1 indication only when performed by an electrophysiologist who has received appropriate training and is performing the procedure in an experienced center.”

“Symptomatic AF prior to initiation of antiarrhythmic drug therapy with a class 2 or 3 antiarrhythmic, Catheter ablation is reasonable.”

[If a paroxysmal patient has no or minimal structural heart disease, their first line choice can be catheter ablation or the antiarrhythmic meds dronedarone, flecainide, propafenone, or sotalol. Should these antiarrhythmics fail, the patient can choose catheter ablation or amiodarone.]

Dr. Calkins also asked “And What About Ablation in Patients with Asymptomatic AF?”

He notes that the indications listed in all guidelines refer only to patients with symptomatic atrial fibrillation. No mention is made of asymptomatic AF. In rare circumstances, it may be reasonable to perform AF ablation in a truly asymptomatic patient with the aim of reducing long term consequences of AF including increased risk of stroke, heart failure, and dementia.

But patients need to be aware of the immediate risks of AF ablation and also that AF ablation has not been shown to reduce the risks of stroke, heart failure, or dementia. [But see my article Live Longer—Have a Catheter Ablation’. In this research (published after Dr. Calkins’ presentation) they found that a successful PVI reduces by 60% the risk of death from stroke and other cardiovascular events. Though some consider this study flawed saying it does not correct for important differences in those who do and those who do not undergo A-Fib ablation.]

ABLATION VS ANTIARRHYTHMIC meds

Dr. Calkins cited a study comparing Radiofrequency Ablation vs. Antiarrhythmic Drugs as First-line Treatment of Symptomatic Atrial Fibrillation. The A-Fib free success rate was significantly higher for catheter ablation. The study concluded “Pulmonary vein isolation appears to be a feasible first-line approach for treating patients with symptomatic AF.”2

But what about possible complications from catheter ablation? [For a more extensive discussion of this topic, see Dr. Keane’s earlier Symposium presentation Risk of Complications from a Catheter Ablation.] Dr. Calkins discussed the RAAFT 2 randomized clinical trial. The CA study found a 7.7% complication rate compared to 19% for patients on antiarrhythmics (AADs). The success rate for CA was 45% [low compared to other studies], while the success rate for AADs was only 28%. In the AAQD study, 59% had to stop at least one drug and nearly half did choose to have a catheter ablation.

In another study, the overall complication rate was 6.9% in patients undergoing AF ablation. But more importantly, the study concluded “there was a significant association between operator and hospital volume and adverse outcomes.”3

DR. CALKINS’ CONCLUSIONS

•  The guidelines have gotten it right.

•  It is difficult to advise that all patients undergo AF ablation as first line therapy given that AF ablation is associated with a significant risk of major complications including death.

•  Clearly a patient’s values and preferences play a big role.

•  But of equal importance is the operator’s own data on success and complications.

•  There is increasing evidence that experience matters when it comes to the outcomes of AF ablation. Most experienced operators have waiting lists.

•  While waiting for an experienced operator, you might as well try an AA drug.

•  It is my impression that the Guidelines are being adhered to. Most patients undergoing ablation today have failed at least one antiarrhythmic medication and have symptomatic AF.

•  Consistent with the guidelines, in rare situations select patients are undergoing ablation as first line therapy.

•  Some asymptomatic or minimally symptomatic patients are undergoing ablation for “theoretical reasons”. “In my mind, this is acceptable provided adequate informed consent has been obtained and patients are aware that the only proven benefit of AF ablation is to improve quality of life.”

Editor’s Comments:
Problems With Today’s Antiarrhythmic Meds
Doctors know all too well that today’s antiarrhythmic meds don’t work very well, or they have bad side effects, or they lose their effectiveness over time. They also tend to cause more and more lasting adverse events than catheter ablation. It’s often safer to have an ablation than to not have one. And the complications from a catheter ablation are most often temporary as compared to living a life in A-Fib or on A-Fib meds.
Also, one of the main reasons people have a catheter ablation is so that they don’t have to take antiarrhythmic meds and anticoagulants for the rest of their lives.
Catheter Ablation First-Line Choice
Today’s guidelines happily take into account these realities. According to current guidelines, you don’t have to spend months or a year trying various antiarrhythmic meds while your A-Fib gets worse, your heart develops more fibrosis, “remodels” itself, and your quality of life is in the toilet.
Then why did 79% of the attendees not recommend A-Fib ablation as first-line therapy? Because, even though catheter ablation is a low risk procedure, it isn’t risk free. The risk is similar to having your tubes tied, i.e. 1-2%. (By comparison, the risks of an appendectomy are around 18%.)
Know Your Rights—Be Assertive
As an A-Fib patient, you should know your rights and be assertive—that according to the guidelines, you have a right to choose catheter ablation as your first choice. Your doctor may try to talk you into first trying antiarrhythmic meds before offering you the option of a catheter ablation.
(The author frequently hears of Cardiologists who refuse to refer patients for a catheter ablation, who tell patients a catheter ablation is unproven and dangerous. When you hear something like that, it’s time to get a second opinion and/or change doctors.)
Current guidelines “recommend” catheter ablation or say it is a “reasonable” option.
Catheter Ablation for Patients Without Symptoms
Dr. Calkins, who headed the committee which drafted the guidelines, goes even further. Patients without symptoms or with minimum symptoms can get a catheter ablation.
”In my mind this is acceptable provided adequate informed consent has been obtained and patients are aware that the only proven benefit of AF ablation is to improve quality of life.”
Side note: It’s questionable whether anyone with A-Fib is really symptom-free. If you have A-Fib, the upper parts of your heart (the atria) aren’t pumping properly. Your body and brain are losing 15% or more of their normal blood flow. People get used to it or they write off the increased fatigue, tiredness, mental slowness, etc. as old age. But anyone with A-Fib is affected by it to some extent.
If you have A-Fib and are symptom-free, you have the option of simply living out the rest of your life in A-Fib. But some people may not be able to do this without worrying about it, e.g., “How is A-Fib affecting my heart, how much fibrosis am I developing, how is my heart remodeling over time?” Realize that you can choose to have a catheter ablation for what Dr. Calkins terms “theoretical reasons”.

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Last updated: Wednesday, September 2, 2015 

 

References    (↵ returns to text)
  1. Epstein AE, et al. 2012 ACCF/AHA/HRS Focused Update Incorporated Into the ACCF/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. Circulation. 2013; 127: e283-e352 doi: 10.1161/CIR.0b013e318276ce9b
  2. Wazni OM, et al. Radiofrequency ablation vs antiarrhythmic drugs as first-line treatment of symptomatic atrial fibrillation: a randomized trial. JAMA. 2005 Jun 1;293(21):2634-40. doi:10.1001/jama.293.21.2634.
  3. Abhishek, D. et al. In-Hospital Complications Associated With Catheter Ablation of Atrial Fibrillation in the US between 2000 and 2010: Analysis of 937,810 Procedures. Circulation. 2013;128:2104-2112. http://circ.ahajournals.org/content/128/19/2104.abstract doi: 10.1161/CIRCULATIONAHA.113.003862

Atrial Remodeling and the Transition From Paroxysmal to Persistent AF by Dr Jose Jalife-2014 Boston AF Symposium

Jose Jalife, MD

Jose Jalife, MD

2014 Boston AF Symposium

Experiments in Atrial Remodeling in Sheep and the Transition From Paroxysmal to Persistent A-Fib

By Steve S. Ryan, PhD

Dr. Jose Jalife of the Center for Arrhythmia Research of the University of Michigan described his experiments inducing A-Fib in sheep by pacing their hearts. He is trying to discover the mechanisms underlying the transition from paroxysmal to persistent A-Fib.

Background: Some patients remain paroxysmal (usually with anti-arrhythmic therapy), while a large proportion progress to persistent A-Fib. (In a study of 5,000+ A-Fib patients, 54% of those on rate control meds went into permanent A-Fib in one year.)1
Previous presentation summary: This talk was a continuation of Dr. Jalife’s 2013 Boston A-Fib Symposium presentation on his experimental studies with sheep. (See A-Fib Produces Fibrosis—Experimental and Real-World Data.) He implanted pacemakers in the hearts of sheep; then induced A-Fib by pacing for 6-30 seconds, then stopped, then paced again, etc. He continued this sequence until the sheep were in persistent A-Fib. He left them in A-Fib for about a year. Dr. Jalife also had a control group of sheep who were monitored but not paced into A-Fib.

Pacing Sheep into A-Fib

Once pacing started in the sheep, it took around 5.5 days to produce the first A-Fib episode. It took around 7-9 weeks of pacing for the sheep to move from Paroxysmal to Persistent A-Fib. At that point the sheep stayed in Persistent A-Fib without any further need of pacing. Dr. Jalife’s sheep developed two major types of atrial remodeling:

  • Structural Remodeling (Fibrosis)
  • Electrical Remodeling (ion channel expression changes)
(In humans, remodeling usually also results in atrial dilation. Dr. Jalife’s sheep once in A-Fib also developed significant Atrial Dilation compared to a control group of sheep.)

Unlike humans, the sheep didn’t develop heart failure, left ventricle dilation and dysfunction, or tachycardia-induced cardiomyopathy despite being in A-Fib for more than a year. This is possibly because sheep have a very good AV Node (unlike most humans) which filters the A-Fib pulses from affecting the ventricles and keeps the ventricular rate low.

Genetic Differences in Sheep

But there were differences in the sheep. Some sheep transitioned into persistent A-Fib fast (<40 days) while others needed more pacing to transition into persistent A-Fib (>40 days). Sheep from the same herd would have the same diet, environment, etc. But genetically they must have been different in their ability to hold out from transitioning into persistent A-Fib.)

Structural Remodeling

All ventricular parameters remained normal in the paced sheep, except for atrial dilation and the markers of fibrosis which increased progressively as the sheep went from paroxysmal to persistent A-Fib. Fibrosis appeared in the right atrium, left atrium and the posterior left atrium. This fibrosis was the result of collagen deposition in the atria which is a permanent remodeling effect of A-Fib.

Dr. Jalife showed slides of a normal pig’s heart compared to a pig in persistent A-Fib. Well over ½ the atria seemed fibrotic.

Mechanisms of Electrical Remodeling

As expected, sustained A-Fib shortened the atrial action potential duration and refractory period. Also, rotor frequencies were increased. For example, in one sheep the dominant frequency of the first episode of paroxysmal A-Fib was 7.3 Hz, but increased progressively to 10.3 Hz during the transition to persistent AF. When AF in that sheep became persistent, the dominant frequent had stabilized at 11.3 Hz and remained constant for up to a year.

Dr. Jose Jalife 2014 Boston AFib Symposium

Graphic used with permission

In perhaps the most important findings of Dr. Jalife’s experiments, the rate of increase in dominant frequency correlated strongly with the time at which AF stabilized. In other words, although the progression from paroxysmal to persistent A-Fib varied from one animal to another, the rate of dominant frequency increase could be used to forecast the time at which AF became persistent.

 In other words, although the progression from paroxysmal to persistent A-Fib varied from one animal to another, the rate of dominant frequency increase could be used to forecast the time at which AF became persistent.

Dr. Jalife and his team also identified the mechanisms of electrical remodeling in sheep, which ion channels in the heart are responsible for transitioning sheep from paroxysmal to persistent A-Fib. Sodium and calcium heart electrical currents were lowered, while potassium and IK1 currents were increased. These electrical changes were associated with gene expression changes “in the alpha subunits of the L-type calcium (CACNA1C) and sodium (SCNSA) channel protein.”

  1. “Sustained AF reduces L-type calcium (Caᵥ1.2) and sodium (Naᵥ1.5) protein expression”
  2. “Sustained AF reduces the rapid sodium inward (INa) and L-type calcium (ICaL) currents”
  3. “Sustained AF reduces the transient outward current (Ito)”
  4. “Sustained AF increases the inward rectifying potassium current (IK1)  and protein expression of the Kir2.3 channel”

Conclusions

The sheep model explains the structural and electrical remodeling that occurs in humans.

As in humans, there is a variable progression in time from paroxysmal to persistent A-Fib.

The rate of dominant frequency increase during such a progression predicts the time at which AF stabilizes and becomes persistent, reflecting changes in Action Potential Duration and densities of ICaL, IK1, INa and Ito.

Predicting the transition from paroxysmal to persistent A-Fib is feasible, at least in some patients, by measuring the increase in dominant frequency over time.

Editor’s Comments:
No one seeing Dr. Jalife’s presentation could doubt that A-Fib produces fibrosis. (Though even among sheep in the same environment, diet, etc. and with a similar gene pool, there were differences in how fast the individual sheep progressed to persistent A-Fib.) As patients with A-Fib, we have to base our medical decisions on the conclusion that A-Fib produces fibrosis; that if we stay in A-Fib over a significant period of time, we will progressively develop fibrosis which is currently irreversible and can lead to a host of other heart problems.

A common strategy today…is to leave you in A-Fib but control your heart rate by the use of beta-blockers, etc. But leaving you in A-Fib produces fibrosis which is irreversible and very damaging to the heart.

A common strategy today for treating A-Fib is to leave you in A-Fib but control your heart rate by the use of beta-blockers, calcium-channel blockers, etc. But leaving you in A-Fib produces fibrosis which is irreversible and very damaging to the heart. If your doctor wants to leave you in A-Fib, Dr. Jalife’s experiments would recommend that you get a second opinion, and ASAP.
One of the major advantages of a successful catheter ablation (and surgery) is it probably reverses the electrical remodeling effect of A-Fib. This makes intuitive sense. A heart beating in normal sinus rhythm (NSR) doesn’t usually produce those weird ion channel currents. But more research needs to be done before we can conclude this. However, a successful catheter ablation does not reverse fibrosis (structural remodeling), though it may reduce atrial dilation.
By identifying the actual mechanisms of electrical remodeling, Dr. Jalife’s ground-breaking experiments may lead to new therapies and drugs to combat not only the transition from paroxysmal to persistent A-Fib, but how to prevent patients from developing A-Fib in the first place. And using dominant frequency to predict when a patient is transitioning to persistent A-Fib, can be an invaluable tool for doctors (and reassuring for patients).
One of the scariest parts of Dr. Jalife’s presentation was how fast he could pace those sheep into persistent A-Fib. Obviously sheep aren’t people. But we know that for most people, there is a relatively short window of time when they progress from paroxysmal to persistent A-Fib (about a year). When you have A-Fib, you can’t count on genetics, diet, life style, environment, etc. to protect you from progressing to persistent A-Fib. Right now we just don’t know why some people stay paroxysmal for years, while most become persistent after a relatively short time. Worst case scenario, you have about a year. Act accordingly.

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Last updated: Wednesday, September 2, 2015 

References    (↵ returns to text)
  1. Peykar, S. Atrial Fibrillation. Cardiac Arrhythmia Institute/Sarasota Memorial Hospital website. Last accessed Jan 5 2013. URL:http://caifl.com/arrhythmia-information/atrial-fibrillation/

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