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It’s another session of CardioNerds Rounds! In these rounds, Dr. Stephanie Fuentes (EP FIT at Houston Methodist) joins Dr. Hugh Calkins (Professor of Medicine and Director of the Electrophysiology Laboratory and Arrhythmia Service at Johns Hopkins Hospital) to discuss the nuances of atrial fibrillation (AF) management through challenging cases. As an author of several guideline and expert consensus statements in the management of AF and renowned clinician, educator, and researcher, Dr. Calkins gives us many pearls on the management of AF, so don’t miss these #CardsRounds! 

This episode is supported with unrestricted funding from Zoll LifeVest. A special thank you to Mitzy Applegate and Ivan Chevere for their production skills that help make CardioNerds Rounds such an amazing success. All CardioNerds content is planned, produced, and reviewed solely by CardioNerds. Case details are altered to protect patient health information. CardioNerds Rounds is co-chaired by Dr. Karan Desai and Dr. Natalie Stokes. 

Speaker disclosures: None

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Show notes – Challenging Cases – Atrial Fibrillation with Dr. Hugh Calkins

Case #1 Synopsis:

A woman in her mid-60s presents with symptomatic paroxysmal atrial fibrillation (AF). An echocardiogram has demonstrated that she has a structurally normal heart. Her primary care doctor had started Metoprolol 50 mg twice a day but she has remained symptomatic. In office, an EKG confirms AF, but she converts to sinus while there. She is seeking advice to prevent further episodes and in general wants to avoid additional medications

Case #2 Takeaways

1. We discussed several potential options for treatment. Amongst the first things we discussed was amiodarone. In a patient of this nature without structural heart disease and under the age of 70, Dr. Calkins discussed that he would probably consider amiodarone as a 2^nd line option. While amiodarone may be effective in maintaining sinus rhythm in comparison to other antiarrhythmic medications like sotalol, flecainide, and propafenone, it does have significant toxicity.
2. If antiarrhythmic drugs (AAD) were to be considered, we also discussed the options of dofetilide versus sotalol. Dofetilide typically requires inpatient initiation due to the risk of QT
    prolongation and Torsades. Since women tend to have longer corrected QT (QTc) intervals, high dose dofetilide may be more proarrhythmogenic in women. Though, Dr. Calkins noted that many patients don’t tolerate sotalol due to fatigue and generally dofetilide is well tolerated.
3. When it comes to the “pill in the pocket” approach, Dr. Calkins noted that its utility is more so in patients with persistent AF that is known to not stop on its own. For instance, an individual who has AF a few times a year that is persistent may benefit from flecainide or propafenone (“in the pocket”) instead of being brought in for an electrical cardioversion. In this scenario, the first time one of these agents is used, the patient ought to be closely monitored. For our patient, her episodes were too frequent and self-terminating for a “pill in the pocket” approach to be effective.
4. Current guideline recommendations for catheter ablation include a Class IA recommendation for patients with paroxysmal AF refractory to AADs, and a Class IIA recommendation as first-line therapy for patients with paroxysmal AF.
5. In the 2020 ESC Atrial Fibrillation Guidelines, catheter ablation is given a Class IA recommendation to improve symptoms of AF recurrences in patients who have failed or are intolerant of one Class I or III AADs. For patients who have failed or have been intolerant of beta blocker alone for rhythm control, catheter ablation is given a Class IIA recommendation. As first-line therapy in paroxysmal AF, catheter ablation is given a Class IIA recommendation as well.
6. Of note, three recent trials have demonstrated catheter ablation as first line therapy is reasonable and newer guidelines will reflect this. Specifically, EARLY-AF compared ablation (cryoablation) vs AAD (mainly with flecainide/propafenone) as a first line therapy. The cryoablation arm showed significantly less recurrence of AF at one year
   • The guidelines clearly state that aligning the treatment plan with the patient’s goals and risk tolerance are paramount. Catheter ablation does have potential complications such as pericardial effusion or access-related issues, though these are rare. Furthermore, as time has passed, catheter ablation success rates have improved.
   • Up and coming techniques such as electroporation may be game-changing with regards to success rate and safety. Waiting times for a procedure may be an issue, so one could consider an AAD, such as flecainide, as a standing dose awaiting the procedure.
7. Regarding predictors of success for catheter ablation, Dr. Calkins noted that the key factor was type of AF. With paroxysmal AF there is roughly 70-80% success rate with the 1^st procedure, 50-70% with persistent AF, and 30-50% with longstanding persistent AF. Other predictors of success include BMI (higher BMI associated with a lower success rate and a higher rate of complications), left atrial size (with a linear dimension of ≥ 5.5 cm indicating less likelihood of success), age, and obstructive sleep apnea.
8. One of the questions that was raised was screening for structural heart disease before starting flecainide/propafenone. Typically, an EKG and TTE are done, and if they are not suggestive of structural heart disease, Dr. Calkins noted it would be reasonable to use these agents. With increasing age, there’s increased risk of subclinical CAD, though it is not in the guidelines to perform functional testing or anatomic imaging prior to starting these agents.
9. Finally, Dr. Calkins noted as an aside that in patients with sick sinus syndrome, management in the past has involved placing a permanent pacemaker (PPM) followed by AAD agents. However, catheter ablation may be a better option because it treats AF and improves the sinus rate because of its effect on the autonomic system, eliminating pauses that would have otherwise warranted a pacemaker. After ablation, the resting HR can improve 10-30 bpm and this can be a marker of successful catheter ablation.

Case #2 Synopsis:

A man in his mid-60s with a history of surgically placed bioprosthetic AVR, CAD with prior CABG, newly diagnosed ischemic cardiomyopathy with LVEF 20-25% with imaging revealing reversible ischemia in multiple coronary territories, presented to the clinic with dyspnea in the setting of persistent AF now 6 weeks after multi-vessel PCI. Other relevant information is that he appears congested in clinic and his EKG demonstrates a left bundle branck block (LBBB) with QRS at 172 ms. He seeks your opinion for management options.

Case #2 Takeaways

1. Dr. Calkins discussed that the only safe AAD in this circumstance would be Amiodarone, and that the risk of developing complete heart block (CHB) in a patient with LBBB placed on amiodarone is not high enough to preclude its use. One strategy would be to give this patient an amiodarone load followed by direct current cardioversion (DCCV). Following DCCV, if the patient maintains sinus rhythm, one could consider continuing with amiodarone at a lower dose or pursuing catheter ablation as a next strategy.
2. Dr. Calkins emphasized understanding the temporal relationship between AF and HF in patients with reduced ejection fraction. In patients with new-onset AF and reduced EF, aggressive rhythm control with catheter ablation would be warranted because there is a higher likelihood of improving the cardiomyopathy.
3. Another option to consider in patients with HFrEF and permanent atrial fibrillation that remain symptomatic or who have had hospitalizations with HF is AV node ablation with cardiac resynchronization therapy, though for a patient like this other viable treatment options remain to be tested. Regarding an ICD, the patient may recover their EF post-revascularization and implementation of guideline-directed therapy. Thus, with ischemic cardiomyopathy post revascularization, the decision to place an ICD should wait 90 days. Furthermore, the EF may improve with control of the AF.

Case #3 Synopsis:

A woman in her mid-80s with hypertension and recent COVID-19 pneumonia is admitted to the hospital with hypoxia, reduced LVEF and found to have AF with rapid ventricular response. The patient’s underlying conditions were treated and attempts at ventricular rate control were attempted but limited by blood pressure. A DCCV with amiodarone loading was also attempted but failed to maintain sinus rhythm. 

Case #3 Takeaways

1. Some feasible options in this circumstance include further loading with amiodarone and reconsidering another DCCV versus an AV node ablation with permanent pacemaker implantation if medical therapies are limited or failing.
2. Digoxin use for rate control alone in critically ill patients is typically discouraged. This is because we now know that its mechanism of action involves raising vagal tone and acutely ill patients typically have low vagal tone so it may not be helpful. However, in patients with rapid AF and HF, it is reasonable to use it. When used in combination with amiodarone, one may reduce the dose of digoxin in half given its drug-drug interaction

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