#159 Atrial Fibrillation Review and Update

July 8, 2019 | By Cyrus Askin

afib Wisdom That Will Give You Palpitations from Cardiologist James Furgerson MD!

Take control of atrial fibrillation with expert insights and pearls from cardiologist, Dr. James Furgerson, in this jam-packed episode! You’ll learn why atrial fibrillation is such a big deal, how to diagnose it, how to treat it and when to call in for reinforcements. Dr. James Furgerson, MD  is a cardiologist from San Antonio, Texas with over 20 years in academics. Buckle up – This episode is going to send your heart racing! You might even skip a beat!

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Credits

• Writer and Producer: Cyrus Askin MD
• Infographic: Cyrus Askin MD
• Cover Art: Cyrus Askin MD
• Hosts: Matthew Watto MD, Paul Williams MD, Cyrus Askin MD
• Editors: Matthew Watto MD
• Guest: James Furgerson MD

Time Stamps

• 00:00 Intro, disclaimer and guest bio
• 03:45 Guest one liner, a bit on physician well-being and some other randomness
• 08:15 A case of palpitations; risk factors for atrial fibrillation
• 12:17 Subclinical atrial fibrillation, overdiagnosis of atrial fibrillation; How much afib burden matters? 
• 15:08 Case summary and next steps in initial work up
• 18:48 Counseling patient about atrial fibrillation and its consequences
• 21:40 Ischemic heart disease and atrial fibrillation
• 24:17 Recap of diagnosis, initial work up and risk stratification in atrial fibrillation
• 25:25 Rate versus rhythm control; AFFIRM trial
• 30:50 Strict versus lenient rate control;  RACE trial
• 33:30 Deciding on rate versus rhythm control; Downside of antiarrhythmic therapies; When to switch from rate to rhythm control strategy
• 36:52 Ablation for atrial fibrillation; CASTLE-AF, CABANA trials
• 40:40 When to refer to cardiology and electrophysiology
• 42:42 Choice of agent for anticoagulation and latest guidelines for atrial fibrillation; New definition for valvular atrial fibrillation
• 45:22 DOACs in CKD and some other nuances in choice of agent
• 52:27 Bleeding and anticoagulation
• 58:38 Cardioversion for atrial fibrillation (initial versus delayed)
• 63:32 Anticoagulation before and after cardioversion
• 67:48 Lifestyles measures for atrial fibrillation
• 70:45 Atrial fibrillation during critical illness, after CABG and in hyperthyroidism
• 74:12 Aspirin monotherapy is not appropriate for atrial fibrillation
• 76:42 Take home points
• 78:50 Outro

Top 5 expert insights from Dr. Furgerson:

1. The keys to prevention are held by the primary care provider.

The power of the relationship between a patient and their primary care provider cannot be overstated! In this case, modifiable risk factors for atrial fibrillation: obesity, obstructive sleep apnea, hypertension and alcohol use disorder – to name a few – can and should be addressed early and often! 

2. Atrial fibrillation is generally a function of structural heart disease that causes elevation of left atrial pressure, especially hypertension.

Long standing hypertension leads to left ventricular hypertrophy and elevated pressure in the left atrium (Note: it’s probably more complicated than that —listen to #150 HFpEF). This in turn causes dilation of the left atrium which disrupts the physiologic electrical conduction of the heart, setting the stage for atrial fibrillation. Less commonly, atrial fibrillation occurs in the setting of a structurally normal heart.

3. Rate control, in most cases of atrial fibrillation, is the preferred approach to therapy.

Symptomatic tachycardia and stroke risk are the major issues seen in patients with atrial fibrillation. Most patients with paroxysmal atrial fibrillation (i.e. suddenly starts and terminates spontaneously or with intervention within 7 days) respond well to rate control alone, typically with a beta-blocker such as metoprolol. Some patients may need two agents. 

Other patients, such as those with concomitant heart failure may benefit from early rhythm control strategies, even though antiarrhythmic agents can be more difficult to manage. These patients may also be candidates for early ablation. 

On the other end of the spectrum, young, highly-athletic patients may develop paroxysmal atrial fibrillation as a function of exercise-induced cardiac remodeling. These patients may be great candidates for an early ablation strategy for persistent symptoms.

4. … speaking of stroke risk, what about anticoagulation?

The decision to initiate or defer anticoagulation is a complicated one, best handled through shared decision making via a patient centered approach.

Remember the CHA2DS2VASc score for calculating stroke risk in a patient (see this calculator from MDCalc). 

The other side of the coin is bleeding risk which also must be considered and may be more nuanced than stroke risk. One place to start is the HAS-BLED score, an accepted risk calculator cited in the JACC’s ACC/AHA/HRS 2019 Update on Atrial Fibrillation (again, see this calculator from MDCalc). 

Generally speaking, if a patient’s bleeding risk is not markedly elevated, a CHA2DS2VASc score ≥ 2 for men or ≥ 3 for women, indicated a patient who would benefit from anticoagulation. 

What agent to start? Again, requires shared decision making via a patient centered approach. The non-vitamin K  oral anticoagulants (NOACs) are excellent options for non-valvular (afib WITHOUT mod-to-severe mitral stenosis or a mechanical heart valve) but dosing must be done based on renal function. Vitamin-K antagonists (VKAs, warfarin in the U.S.) are the drug-of-choice for valvular atrial fibrillation. 

5. To Cardiovert or Not To Cardiovert… 

Synchronized cardioversion (a shock delivered in synchrony with the patient’s native QRS complex) can be used to electrically convert a patient in atrial fibrillation to normal sinus rhythm in certain circumstances.

Patients with hypotension/hemodynamic instability, or those with pre-excitation on their EKG are good candidates for cardioversion which should be done without hesitation (i.e. TEE to check for mural thrombus is NOT required for emergency cardioversion).

Acute, ongoing ischemia with new-onset atrial fibrillation and rapid ventricular response – Class 1c recommendation for urgent cardioversion per 2014 ACC/AHA/HRS guideline

Highly symptomatic patients: Consider cardioversion. May defer TEE in patients with a known long-standing history of atrial fibrillation, adherent to chronic anticoagulation.

What are the options for cardioversion for new-onset atrial fibrillation or atrial fibrillation of uncertain duration? 

1. TEE prior to cardioversion while on effective anticoagulation with at least 4 weeks of therapeutic anticoagulation to follow (continue indefinitely if suggested by stroke risk)
2. Alternatively, may therapeutically anticoagulate for at least 3 weeks prior to cardioversion and continue for at least 4 weeks afterwards, in lieu of TEE.

Atrial Fibrillation Studies, Guidelines & Insights From The Show

2014 ACC/AHA/HRS Guideline on Atrial Fibrillation

In some ways, this comprehensive reference discussing the pathophysiology, diagnosis and management of atrial fibrillation in numerous populations was the cornerstone for our discussion. We specifically examined  the interplay between heart failure and atrial fibrillation with Dr. Furgerson. He mentioned the preferential use of rhythm control in atrial fibrillation when a patient is thought to develop heart failure secondary to their atrial fibrillation (see page e46 in the above document for more).  Additionally, with respect to atrial fibrillation and heart failure in general,  there is a IIa recommendation to combine digoxin (a rate and rhythm control agent) with a beta-blocker, if necessary to improve symptoms (see section 7.9). 

2019 ACC/AHA/HRS Focused Updated to the Guideline on Atrial Fibrillation:

This is an important update to the aforementioned guideline which we discussed during our show. Dr. Furgerson specifically pointed out the following:

• Class 1a indication for NOACs over VKAs in most cases of atrial fibrillation
• Class 1b indiciation for weight loss in obese patients – evidence suggests weight loss “reduced symptom burden and severity and reduced the number of AF episodes and their cumulative duration  ( see Abed, 2013)
• Both warfarin and apixaban, are acceptable for patients with CKD-5/ESRD (class 2b)
• Class 2b indication for catheter ablation for atrial fibrillation in HFrEF due to “New evidence, including data on improved mortality rate, has been published for atrial fibrillation catheter ablation compared with medical therapy in patients with heart failure.”

AFFIRM Trial

In this 2002 landmark randomized controlled trial of > 4000 patients published in the New England Journal of Medicine, the investigators found no difference in survival benefit when comparing rate versus rhythm control in atrial fibrillation. Specifically, there was no statistically significant difference in 5-year mortality. However, there were statistically significant differences (favoring rate control) regarding rate of hospitalization, incidence of torsades and PEA/bradycardia. Dr. Furgerson discusses that, as a function of AFFIRM the 2014 ACC/AHA/HRS Guideline on Atrial Fibrillation states “routine use of a rhythm control strategy is not warranted for some patients” and that “an initial rate-control strategy is reasonable for many patients.” In Dr. Furgerson’s practice, he prioritizes addressing any reversible/modifiable conditions that may be associated with atrial fibrillation and then attempting a rate-control strategy with a beta blocker or calcium channel blocker. 

RACE II

This 2010 study was briefly discussed by Dr. Furgerson during our show.  It was a randomized non-inferiority study of around 600 individuals with permanent or persistent atrial fibrillation, split into a lenient rate control group (<110 bpm) vs. a more strict rate control group (<80 bpm). The goal was to identify differences between the groups with respect to cardiovascular outcomes. To this end, the study focused on a composite CV end-point which included things like CV mortality, CHF, stroke, VTE and development of life-threatening arrhythmias.  The researchers found lenient rate control was non-inferior to strict rate control & easier to achieve (not surprisingly!). Furthermore, there was a signal suggestive of fewer complications! Dr. Furgerson uses this study to support a lenient strategy in his patients…but only when the lenient strategy is sufficient to mitigate their symptoms. 

PIONEER AF-PCI

While not a major point of discussion during our show PIONEER AF-PCI is an important study as it pertains to anticoagulation in patients with atrial fibrillation and CAD who require PCI. Traditionally, these patients have been placed on dual-antiplatelet therapy (DAPT) and warfarin. Dr. Furgerson, discussed the rise of NOACs and waning use of  warfarin. Specifically, the PIONEER AF-PCI study placed patients into three basic groups: a full dose rivaroxaban + P2Y12 inhibitor group x 12 months (group 1), reduced-dose rivaroxaban + DAPT x 1, 6 or 12 months (group 2) or DAPT + warfarin x 1, 6 or 12 months (group 3). While the findings are a bit nuanced, the overall findings suggest greater risk of bleeding in those on warfarin than those not placed on warfarin. Furthermore, those that were spared warfarin did not have more in-stent thrombosis events, nor did they suffer from more strokes, MIs, or greater rates of CV mortality, although the study was limited in its ability to assess the efficacy of these agents on outcomes other than bleeding. 

CASTLE-AF

During the episode, we discussed catheter ablation and populations for which it can be beneficial. Dr. Furgerson cited some of the data from this 2018 study as it pertains to the potential benefits of early atrial fibrillation ablation in patients with HFrEF vs. medical therapy. The pathophysiologic underpinning is the thought that patient’s with HFrEF and thus, already compromised cardiac output, are even further compromised when in atrial fibrillation. Thus, the researchers postulated that getting these patients out of atrial fibrillation while reducing their pill burden & polypharmacy, could prove beneficial. The primary outcome was death or hospitalization for heart failure. Those randomized to the early ablation group had significantly fewer heart failure hospitalizations than those placed on medical therapy. It is important to note that this study had significant industry involvement in addition to very specific inclusion  & exclusion criteria (ex. EF ≤ 35%, no prior ablation attempts) which impacts the generalizability of these findings.

CABANA

Dr. Furgerson compared the findings of CASTLE-AF to the 2019 CABANA trial. In this study, there were many more patients enrolled with fewer inclusion criteria, as compared to CASTLE-AF. Therefore, the findings of this study also looking at catheter ablation vs. medical management in atrial fibrillation, are more generalizable in comparison. The primary outcome for this study was also a composite, looking at the incidence of death, disabling CVA, major bleeding or cardiac arrest. No statistically significant difference was found, although there was a high cross-over rate which may impact the results to some degree. During our discussion, this study along with CASTLE-AF frame Dr. Furgerson’s practice to consider referral for early antiarrhythmic use and early ablation in HFrEF patients, but generally not taking this approach with all-comers. Of course, there are other populations that may benefit from early ablation (such as young athletes, discussed in the show) but these folks generally fall outside the scope of either CASTLE-AF or CABANA (average age 68) .

RACE 7 ACWAS

While not discussed specifically, Dr. Furgerson wanted to include this study in the show notes as it pertains to our chat about cardioversion in atrial fibrillation. This study, published in 2019, looked at whether restoration of sinus rhythm by pharmacologic or electrical cardioversion within 48 hours of onset of atrial fibrillation was beneficial for return to sinus rhythm at 30 days. They concluded that a “wait-and-see” approach to cardioversion in new-onset atrial fibrillation was non-inferior to early cardioversion. The results can be explained by a spontaneous conversion to normal sinus rhythm that occurs in patients while receiving rate control. 

Goals

Listeners will appreciate the significance of early diagnosis and management of atrial fibrillation, to include rate versus rhythm control, control of risk factors and need for anticoagulation. 

Learning objectives

After listening to this episode listeners will…  

1. Respect the importance of atrial fibrillation, specifically as it relates to the increased risk of stroke and tachycardia-induced cardiomyopathy
2. Develop a basic understanding of the pathophysiology and risk-factors associated with atrial fibrillation
3. Order the appropriate labs and studies while attempting to diagnose atrial fibrillation.
4. Counsel patients once they are diagnosed with atrial fibrillation
5. Be introduced to common management conundrums: rate versus rhythm control and need for anticoagulation
6. Confidently identify patients who may benefit from more advanced therapies (antiarrhythmics, ablation)
7. Appreciate the approach to cardioversion, to include patient selection and pre/post care

Links

Provided in text above.

Recommended Reading 

1. Annals in the Clinic – Atrial Fibrillation (https://annals.org/aim/fullarticle/2607807/atrial-fibrillation?searchresult=1)
2. AAFP & ACP Guideline for NEW atrial fibrillation (https://annals.org/aim/fullarticle/716992/managemet-newly-detected-atrial-fibrillation-clinical-practice-guideline-from-american)
3. 2018 – Efficacy and safety of reduced-dose non-vitamin K antagonist oral anticoagulants in patients with atrial fibrillation (https://www.ncbi.nlm.nih.gov/pubmed/30590440/)
4. 2019 – HRS Manuscript – Patient Reported Triggers for Paroxysmal Atrial Fibrillation (https://www.heartrhythmjournal.com/article/S1547-5271(19)30099-2/fulltext)
5. 2018 – Caffeine Intake Inversely Associated with Incident afib? (https://journals.sagepub.com/doi/full/10.1177/2047487318772945?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub%3Dpubmed)

Disclosures

Dr . Furgerson  reports no relevant financial disclosures. The Curbsiders report no relevant financial disclosures. 

Citation

Furgerson, James. Guest expert. “#159 Atrial Fibrillation”. The Curbsiders Internal Medicine Podcast. http://thecurbsiders.com/episode-list. July 8, 2019.