To Fib or Not To Fib: Atrial Fibrillation Definition, Causes, Presentation

This podcast series aims to highlight the prevention, diagnosis, and treatment of patients with diseases commonly seen in internal medicine. Host, Anil Harrison, MD, discusses patient cases with residents and with prominent experts to help educate clinicians in treating patients using a multidisciplinary approach.

In this podcast episode, Dr Harrison discusses atrial fibrillation, including its definition, causes, presentation, physical examination findings, and consequences. He also discusses six case presentations, including rate vs rhythm control, whether to anticoagulate, which anticoagulant to use, whether to bridge, and the WATCHMAN procedure. 

For more atrial fibrillation content, visit the resource center. 

Anil Harrison, MD, is the Program Director and Chair of the Internal Medicine Residency Program at the University of Central Florida and HCA Florida West Hospital (Pensacola, FL). Dr Harrison is board certified in India and the United States.

TRANSCRIPTION:

Jessica Bard:

Hello everyone, and welcome to Multidisciplinary Dialogue: Clinical Rounds and Case Reviews with your host, Dr Anil Harrison, who is the Program Director and Chair of the Internal Medicine Residency Program at the University of Central Florida and HCA Florida West Hospital in Pensacola, Florida. 

Today’s episode is titled To Fib or Not to Fib. We’ll discuss atrial fibrillation and related case presentations. The views of the speakers are their own and do not reflect the views of their respective institutions or the views of Consultant360. 

Good morning, Dr. Harrison. How are you today?

Dr Anil Harrison:

Good morning, Jessica. I'm doing very well, thank you. How about yourself?

Jessica Bard:

Good. I'm doing great. Thank you. Our podcast today is on atrial fibrillation. We'll call it "To Fib, or Not To Fib?"

Dr Anil Harrison:

That's a good one.

Jessica Bard:

Yeah, it's good, right? So we'll talk about what is atrial fibrillation, its causes, its presentation, physical exam findings, and its consequences, before we go into more specific scenarios such as rate versus rhythm control, to anticoagulate or not to anticoagulate, which anticoagulant to use, to bridge or not to bridge. And lastly, the Watchman's procedure. We also have six short case presentations and scenarios that we'd like to discuss with you, but are you ready to get started?

Dr Anil Harrison:

Absolutely, Jessica.

Jessica Bard:

Well, let's start with this. What is atrial fibrillation and what are some of its causes?

Dr Anil Harrison:

Sure. So atrial fibrillation, as you said, fibbing, is an irregular and often very rapid heart rate that can lead to blood clots in the heart, putting it very simply. Atrial fibrillation increases the risk of stroke, heart failure, and other heart-related complications. During atrial fibrillation, the heart's upper chambers, they're called the atria, beat chaotically and irregularly. And they're out of sync with the lower chambers called the ventricles of the heart. For many people, atrial fibrillation may have no symptoms at all. However, atrial fibrillation may cause a fast, pounding heartbeat, called palpitations, shortness of breath, and weakness.

So some of the causes, Jessica, could be alcohol-related, especially binge drinking. It could be related to coronary artery disease, heart attacks or bypass surgeries, heart failure, or if somebody has an enlarged heart. And of course, it also can be related to heart valve disease, most often the mitral valve, which sits between the left atrium and the left ventricle. Another etiology would be hypertension. Certain medications can do that. An overactive thyroid gland called hyperthyroidism can do that. Pericarditis can do that. And of course, a sick sinus syndrome can also do that. So some of the symptoms, as I said, a person might be absolutely asymptomatic, but sometimes you feel a pulse that feels rapid, it's racing, it's pounding, it's fluttering, it's irregular or it's too slow. And the sensation of heart beat is very prominent in some people. They're called palpitations. And because of a lack of blood supply to the brain, one can have dizziness, lightheadedness, confusion, feeling faint, and feeling fatigued. There's a loss of ability to exercise. And people can get short of breath as well.

Jessica Bard:

What are some of the physical examination findings in atrial fibrillation?

Dr Anil Harrison:

Sure, so an irregularly irregular pulse. Also, when one osculates the heart, besides the irregularity, one may also detect a discrepancy between the heartbeat while osculating and the pulse rate when palpating the radial artery. On auscultation, one might hear a varying intensity of S1. Besides, one wants to know if there are any murmurs, gallops, or pericardial rubs. The JVD might also be elevated, and one might hear crackles at the basis of the lungs, signs of heart failure. An EKG, which is a test that records the electrical activity of the heart, may show atrial fibrillation or flutter. If your abnormal heart rhythm comes and goes, you may need to wear a special monitor to diagnose the problem, depending on the frequency of the problem. The monitor records the heart's rhythm over a period.

So for example, if you're having symptoms every one to two days, a halter monitor would be the way to go, but you always start off with an EKG first. If your symptoms occur, let's say, every few days or in a couple of weeks, then a patch recorder would be the way to go. If your symptoms were to occur once every three to four weeks, then an event monitor would be the thing to go with. But if you have symptoms once in a while, let's say once or twice or twice or thrice a year, then an implanted loop recorder for events occurring occasionally would be the way to go. So some of the tests to find heart disease may include an echocardiogram, which is an ultrasound of the heart, and tests to examine the blood supply of the heart muscle, which is a cardiac cath, or a CT angiogram. And of course, very importantly, tests to find the heart's electrical system, called EPS, or electrophysiological studies are also important.

Jessica Bard:

How does one treat a patient with atrial fibrillation?

Dr Anil Harrison:

So the treatment depends on the stability of the patient, Jessica. If the patient is hemodynamically unstable, one would attempt to give electric shocks to the heart, called cardioversion, along with drugs given intravenously to try and revert the abnormal rhythm back to normal. If the patient is hemodynamically stable, one thing to consider is do you want to go with rate control or rhythm control, which means do you want to slow the ventricular rate or do you want to convert the atrial fibrillation to normal sinus rhythm? Having said that, some of the greatest risks with atrial fibrillation are systemic embolization, which can result in a stroke or complications secondary to an embolus elsewhere. It also can result in heart failure, and coronary events, and in certain cases, dementia is also associated with longstanding atrial fibrillation.

You see, the problem with atrial fibrillation is atrial fibrillation begets atrial fibrillation; just as you mentioned, fibbing begets fibbing. What this means is that atrial fibrillation results in chronic remodeling structurally, electrically, and autonomically. So some of the terminologies used with atrial fibrillation are, number one, subclinical atrial fibrillation, also termed as AHRE, or atrial high rate events, where during cardiac monitoring in asymptomatic patients, atrial fibrillation is discovered happening for about five to six minutes at a rate of 175 beats per minute or more. These folks eventually do develop atrial fibrillation.

The second one is paroxysmal atrial fibrillation, which lasts for less than seven days, whereas persistent atrial fibrillation, which lasts for more than seven days or with treatment becomes sinus rhythm. On the other hand, persistent atrial fibrillation is atrial fibrillation, which lasts for a year. And longstanding persistence is anything more than that. There's a term called chronic atrial fibrillation, which is a term determined by the physician and the patient. Another categorization for atrial fibrillation is valvular and non-valvular atrial fibrillation. Atrial fibrillation may be related to valvular heart disease, especially moderate to severe mitral stenosis. Non-valvular atrial fibrillation is related to either normal valves or anything else, considering the etiologies that I mentioned.

While addressing atrial fibrillation and the complications which can result if untreated, the questions that come to one's mind are, should one be anticoagulated? Which anticoagulant should one use? Are all anticoagulants the same? Should one focus on rate control or rhythm control? And if it is rhythm control, should one use drugs or should one use radiofrequency ablation? You see, the problem with atrial fibrillation is that the atrium is in a tizzy and chaos, with the blood within being churned, producing clumps called clots, which can then travel to the brain or elsewhere systemically, causing neural or tissue ischemia, which can be devastating at times.

Jessica Bard:

Could you speak about the 48-hour rule with atrial fibrillation?

Dr Anil Harrison:

Absolutely, Jessica. Since time does have relevance to atrial fibrillation, let us first address the 48-hour rule. If we are certain that the atrial fibrillation has been present for less than 48 hours, the patient does not need to be anticoagulated. One can go ahead and cardiovert the heart rhythm to normal sinus rhythm. Although if one is uncertain with regards to the actual timing, getting a TEE, transesophageal echocardiogram, before proceeding with cardioversion is reasonable. The reason for this is the CHA2DS2-VASC is less than two, and hence the risk for a stroke, is 0 to 0.4. Therefore, this is a class IIb recommendation to offer no anticoagulation after cardioversion. On the contrary, if the atrial fibrillation has been present for more than 48 hours, one must anticoagulate for three weeks prior to cardioverting, followed by at least four weeks of anticoagulation, with decisions on the length of anticoagulation beyond this, be determined by doing a CHA2DS2-VASC scoring.

Jessica Bard:

How does one balance the purpose of anticoagulation versus the chances of having a major bleed secondary to the anticoagulant?

Dr Anil Harrison:

That's a great question, Jessica. Should one anticoagulate? That's a question. It depends on what is the risk of a person developing a clot and therefore treating it with anticoagulants, versus what are the risks of the person having a major bleed, which again, can be significantly detrimental. To address this, the CHA2DS2-VASC score is used to determine the risk of clotting/thrombosis, whereas the pneumonic HAS‐BLED is used towards the chances of a person bleeding from being on anticoagulants. The risk of embolization of stroke secondary to atrial fibrillation uses the CHADS2VaSc scoring.

The CHADS2, a clinical prediction rule formula for estimating the risk of stroke in patients where the non-rheumatic atrial fibrillation comprises C, which is for congestive heart failure, H for hypertension, which means blood pressure greater than 140 over 90, A for age greater than 75, D for diabetes, and S for prior TIA or stroke. With an age greater than 75 and a prior history of TIA or stroke, you get two points, while the others get one point each. By points directly, for example, six points, which is a maximum, relates to an 18.2% risk per year if no coumadin is given, which is a high risk, as opposed to having zero points, the risk is just 1.9% per year if no coumadin is given.

The other one, the CHA2DS2-VASC score, where A and S, which is age and a history of stroke and TIA, get two points each again, which is similar, though the CHA2DS2-VASC score has a maximum of 10, where again, C stands for congestive heart failure; H, hypertension; A, capital A, age greater than 75; D for diabetes; S for stroke or TIA or systemic embolization; V for vascular disease; a, the small A, for age between 65 to 74; and capital S and small C for the female sex. Again, one gets two points for age greater than 75 and for stroke or TIA, or systemic embolization. The higher the risk, the higher the risk of thromboembolic phenomenon.

And conversely, the smaller the score, the smaller is the risk. With zero points, the stroke/systemic embolization risk was about 0.2% to 0.3% per year. A score of one for men and two for women is low to moderate risk. And one might consider anti-platelet or anticoagulation. A score of two or more in men and a score of three or more in women is moderate to high risk, and they should be on anticoagulants.

This, of course, must be balanced with what is the risk of major bleed while being on anticoagulants, for which the pneumonic HAS‐BLED, which calculates the risk of major bleed from zero to nine. The higher the number, the higher the chances of bleeding, where H stands for hypertension, a systolic blood pressure of more than 160; A for abnormal liver and/or kidney functions; S for a history of stroke; B for major prior bleeding or predisposition to bleeding; L for a labile INR; E for elderly, which means person greater than age 65; and D for drugs or alcohol.

With this scoring, the HAS‐BLED scoring, with zero points, the risks of a major bleed are 0.9 to 1.13 per year, which is low risk. And up to two points, anticoagulation can be considered, though the risk is moderate, which means two per 100 patient-years. Three and above are at high risk for a major bleed, 5.8%. And alternatives to anticoagulation should be considered. Scores greater than five are rare to determine, but the risk for a major bleed is likely more than 10%. So, Jessica, it makes sense that if the CHA2DS2-VASC score is much greater than the HAS-BLED score, one should anticoagulant. Besides, when addressing this issue, one must keep in mind that the chances of thrombotic or embolic events are much higher than the chances of bleeding.

Jessica Bard:

We know the names of the anticoagulants. Could you briefly summarize these and help us determine which one to use under which conditions?

Dr Anil Harrison:

Yes, absolutely. So one of the older anticoagulants, which we still on occasion use, is warfarin, which happens to be inexpensive. We also have years of experience with it. And it can be reversed if the patient is over-anticoagulated. The newer ones are called DOACs, which stands for direct oral anticoagulants, implying that, unlike warfarin, which works on factors II, VII, IX, and X, the DOACs act or reverse usually one component only along the coagulation pathway, such as be it factor II or factor X. Some DOACs have better efficacy and superiority when compared to warfarin, while the others are not inferior to warfarin.

The DOACs cause less bleeding when compared to warfarin, are more convenient because there are no food interactions, and have fewer drug interactions. Their half-lives are about 10 to 12 hours. The disadvantages of warfarin are food interactions with foods containing vitamin K. There are drug interactions through the cytochrome P450 system. The half-life can range from 20 to 60 hours. And the problematic frequent INR measurements that go with warfarin can be cumbersome. The disadvantages of the DOACs are we do not have enough experience, especially with saddle embolism, heparin-induced thrombocytopenia, and folks who have chronic kidney disease. There can be drug interactions with the P-glycoprotein metabolized medications, especially with dabigatran, phenytoin, carbamazepine, et cetera. They are expensive when compared to warfarin.

Jessica Bard:

What would be the instances where one would use warfarin?

Dr Anil Harrison:

One can only use warfarin and not DOACs for valvular atrial fibrillation, especially secondary to moderate to severe mitral stenosis. Also, one can use warfarin if a person has a mechanical heart valve, whereas one cannot use the CHA2DS2-VASC scoring. And warfarin is recommended also in instances where one visualizes a thrombus in the atria or the ventricle. For all others, DOACs can be used.

Jessica Bard:

Now, there are several DOACs. Which one do we choose?

Dr Anil Harrison:

Yeah, that's a good question, Jessica. You see, there are no head-to-head studies comparing all DOACs. But if I had to pick one, it would be apixaban, called Eliquis. In a meta-analysis published in 2017, ACPE, apixaban, or Eliquis, had the best combination of reducing strokes, reducing mortality, less bleeding, and cost-effectiveness. And it can be used in advanced renal failure as well.

Jessica Bard:

What if the patient has significant bleeding while on anticoagulants?

Dr Anil Harrison:

Well, if it is because of warfarin, you can reverse that, or you can try and reverse it with vitamin K or fresh frozen plasma, or with prothrombin complex concentrates. If the bleeding is because of DOACs, remember the pneumonic PAP: prothrombin complex concentrates, Andexanet alfa, or Praxbind, especially if the person is on dabigatran.

Jessica Bard:

We go through dilemmas where a person is on an anticoagulant and needs a procedure conducted, and we are uncertain whether we ought to bridge with unfractionated heparin or low molecular weight heparin to reduce the chances of clotting while also wondering about excessive bleeding during the procedure. How should one proceed?

Dr Anil Harrison:

The answer to this dilemma, Jessica, is if it is an emergent procedure, and there is little time to think, since life is at stake, one proceeds with the emergency, acknowledging the risks involved. On the contrary, if it is an elective procedure, one can once again reason by doing the CHA2DS2-VASC scoring to see what the risks are of the patient developing a clot versus the risks of bleeding, by using the HAS-BLED mnemonic. Remember, studies have revealed that bridging has more risks of thromboembolic phenomenon.

Jessica Bard:

What do you mean by the risk of thromboembolism? And what are the determinants, especially for high-risk?

Dr Anil Harrison:

Yeah, that's a great question again, Jessica. So high risk of a thromboembolic risk is defined as greater than 10% of events per year. 5% to 10% events per year is intermediate risk, whereas low risk is less than 5% event per year. There's a pneumonic that I have created so that I can remember, and this is for high-risk issues, with certain necessity bridging with unfractionated or low molecular weight heparin. And the pneumonic is STREAM. It's something like, one must bridge over this turbulent stream, where S stands for stroke, recent TIA or a stroke in the past three to six months; T for severe thrombophilia, examples being deficiencies of protein C or S, or antithrombin III, if one has antiphospholipid antibodies, multiple abnormalities; R is for rheumatic valvular heart disease; E is for embolism or VTE in the last three months; A is for atrial fibrillation with a CHA2DS2-VASC score of five or six. And M is for mechanical heart valve, which is any mitral valve prosthesis or any cage ball or tilting disc in the aortic valve area.

With this high risk, the patient must be bridged with unfractionated or low molecular weight heparin. On the contrary, one should not bridge if the scores of CHA2DS2-VASC is low, such as two or less. For the in-between, which means between two and five, one should determine the risk of thromboembolic phenomenon versus bleeding risk and make a calculated cohesive decision with the patient while doing this.

Jessica Bard:

The next question is rate control versus rhythm control in folks with atrial fibrillation. Which does one choose?

Dr Anil Harrison:

Yeah, the pendulum has been swinging. When I was training a million years ago, we focused on rhythm control. And this then was followed by studies, which revealed rate control was better, and so we switched to controlling the ventricular rate. And now recently, again, in certain scenarios, we are going back to rhythm control, though the new trials are disparate. Factors to consider when contemplating rhythm control, the earlier on one does it in atrial fibrillation, the better. It can also certainly be considered in cases of heart failure with reduced ejection fraction, and with patients who have symptomatic significant palpitations. Whenever rhythm is a consideration, one considers radiofrequency ablation versus antiarrhythmics. We have good experience controlling the ventricular rate in atrial fibrillation by using beta blockers or digoxin or non-dihydropyridine calcium channel blockers such as Cardizem and verapamil.

Jessica Bard:

Could you talk a little bit about rhythm control?

Dr Anil Harrison:

Yeah, sure. So early catheter ablation in atrial fibrillation led to improved quality of life, better exercise tolerance, and fewer palpitations. Studies such as CABANA, CASTLE-AF, and EAST studies suggest perhaps better mortality and stroke outcomes with rhythm control. Of note, remember, we still need to anticoagulate two months after ablation. And additionally, this might be extended based on the patient's CHA2DS2-VASC scoring.

Some of the medications for rhythm control are the class IC, flecainide and propafenone; class III, amiodarone, dronedarone, sotalol, dofetilide, and ibutilide. Vernakalant is available in Europe only and is a sodium- and potassium-channel blocker. So, on the class I antiarrhythmics, which are the sodium channel blockers, flecainide, and propafenone, flecainide should be avoided in structural heart disease involving left ventricular hypertrophy, and should always be used with a beta-blocker. Propafenone should be avoided in NYHA III and IV heart failures, along with patients who have hypotension.

Amiodarone, which is a sodium, potassium, calcium-channel blocker and a beta blocker, the half-life is an issue. It's 60 days. It has minimal QTC effects. Its side effects include involving the thyroid, the lungs, the cornea, and the liver. Dronedarone, which is a modified amiodarone, is not as good as amiodarone. The half-life, though, is less than a day. Mortality is increased with stroke, heart failure, and atrial fibrillation. Dofetilide is the oral form, and ibutilide is the intravenous form. Dofetilide needs a special certification, which must be initiated in the hospital for closed QT monitoring. Ibutilide can cause prolonged QT and torsades, though it can be used concomitantly with electrical cardioversion.

Jessica Bard:

Could you tell us about the Watchman's procedure, and where it has a role?

Dr Anil Harrison:

The PREVAIL study recommends warfarin aspirin for 45 days post-procedure, following which a TEE needs to be done. If the left atrial appendage opening, or the LAAC, is less than five millimeters, warfarin can be discontinued, but Plavix and aspirin need to be instituted for six months. And after six months, the Plavix can be stopped and aspirin has to be continued indefinitely. The Watchman meta-analysis was non-inferior to warfarin for the composite endpoint, which is stroke and embolization as well as death. Of note, ischemic CVA is worse with the device, hemorrhagic CVA is worse with warfarin. So with the above, according to the PROTECT atrial fibrillation trial, with the procedure, there was an 85% relative risk reduction in hemorrhagic stroke, 60% in cardiovascular mortality, 1.4% absolute annual risk reduction in cardiovascular mortality, and a 34% relative risk reduction mortality, and 1.6% absolute reduction all-cause mortality.

Jessica Bard:

Are there any problems with the Watchman's procedure? When should one consider the Watchman's procedure?

Dr Anil Harrison:

Yeah, there are problems with the procedure, such as concerns for developing a pericardial effusion requiring intervention in 5%, and ischemic stroke in 1.1%. 1% can develop ... need a device removal, due to device migration. And 2.2% led to cardiovascular surgery. And confounding, there's also this confounding use of Plavix for seven days prior to the procedure. Making it simple, Jessica, the above procedure can be done in folks who cannot or will not take warfarin, though 45 days of warfarin is required after the procedure.

Jessica Bard:

All right, and we made it to the case presentations. We've got six case presentations that we'd like to go over with you, Dr. Harrison. In our first case scenario, a healthy 40-year-old presented with palpitations for two days and was found to have fibbing. What do you do, Dr. Harrison?

Dr Anil Harrison:

Okay. So a 40-year-old presents with palpitations for two days and is found to have atrial fibrillation. Okay, so if confirmed that this is less than 48 hours, the CHA2DS2-VASC score is less than two, this patient does not need to be anticoagulated and therefore can be cardioverted.

Jessica Bard:

Next, a 65-year-old with diabetes, hypertension, coronary artery disease, heart failure with low EF, and atrial fibrillation for years, on maximum-tolerated beta blockers and on an anticoagulant, presents with disabling palpitations. What do you do?

Dr Anil Harrison:

Okay, 65, has diabetes, hypertension, CAD, heart failure ... 1, 2, 3. So this patient, Jessica, has a CHA2DS2-VASC of four and has disabling palpitations with heart failure and reduced ejection fraction. This patient might benefit from rhythm control, given the disabling palpitations.

Jessica Bard:

A 50-year-old with hypertension, sleep apnea, and atrial fibrillation, on a DOAC, requires an elective endoscopy in five days to evaluate guaiac-positive stools. Would you bridge?

Dr Anil Harrison:

So 50-year-old with hypertension has atrial fibrillation and is on a DOAC. This patient's CHA2DS2-VASC is one, therefore, he does not require bridging. No.

Jessica Bard:

All right. It's like rapid fire here, Dr. Harrison. A 75-year-old with chronic atrial fibrillation on warfarin presents with multiple evaluations with endoscopies for anemia and atrial venous malformations discovered in the small bowel. What will you do?

Dr Anil Harrison:

Okay, a 75-year-old with chronic atrial fibrillation, on warfarin with multiple evaluations for anemia, is found to have arterial venous malformations in the small bowel. What will you do? So long-term, warfarin and AVMs found repeatedly in endoscopies when evaluating for anemia and guaiac-positive stools, this patient might benefit from a Watchman's procedure. At the most, he's going to require, as we mentioned, six weeks of warfarin. But after that, hopefully, he'll be off Warfarin, and his guaiac-positive stools and his anemia should resolve.

Jessica Bard:

Next, a 65-year-old with diabetes, hypertension, and a history of transient ischemic attack three months ago, who also has peripheral artery disease, presents with shortness of breath for two weeks and is found to have atrial fibrillation. What will you do, Dr. Harrison?

Dr Anil Harrison:

Okay, Jessica. So this patient presents with new-onset atrial fibrillation. Even though his EKG may not have revealed ischemic changes, this patient has several risk factors for coronary artery disease. He's 65, he has diabetes and hypertension. He's had a TIA three months ago, and he also has a PAD. So coronary artery disease will need to be evaluated in this patient, but he will need an echo; as well as with a CHA2DS2-VASC score, which I think is six in this case, he will need to be anticoagulated as well.

Jessica Bard:

Lastly, in our rapid-fire case presentations, a 25-year-old presents with gradually progressing shortness of breath. On auscultation, she has an opening snap and a mid-diastolic rumble at the apex. An EKG reveals atrial fibrillation. What will you do?

Dr Anil Harrison:

So this patient seemingly has mitral stenosis, along with atrial fibrillation. She will require an echocardiogram and will need to be placed on warfarin, besides, of course, considering mitral valve repair.

Jessica Bard:

Well, that concludes our episode for today, Dr. Harrison. Thank you so much for walking us through all of that and for even being a good sport during our rapid-fire around there of case presentations. I think we learned a lot and probably reinforced some things we already knew. How do you feel about the episode today? Was it a good one?

Dr Anil Harrison:

I think so. We'll leave it to the listeners to see if they feel it's worthwhile, but thank you so much, Jessica.

Jessica Bard:

Thank you. Well, tune in next time for our next episode of Multidisciplinary Dialogue, Clinical Rounds, and Case Reviews. Have a great day.