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In this episode, CardioNerds Dr. Colin Blumenthal, Dr. Kelly Arps, and Dr. Yong Hao Yeo are joined by electrophysiology expert Dr. Bradley Knight to discuss atrial fibrillation (AF) management in challenging clinical scenarios. We explore arrhythmias in patients with pre-excitation syndromes, particularly Wolff-Parkinson-White (WPW) syndrome, and strategies for rhythm control. We also discuss AF management in pregnancy, adult congenital heart disease, and patients with tachycardia-bradycardia (tach-brady) syndrome. This episode provides essential insights into nuanced decision-making for the care of patients with complex arrhythmia profiles. Audio editing by CardioNerds academy intern, Grace Qiu.

Enjoy this Circulation 2022 Paths to Discovery article to learn about the CardioNerds story, mission, and values.

PEARLS

1. AF in WPW is a true emergency—AV nodal blocking agents can be deadly. In patients with WPW syndrome, AF can rapidly conduct through the accessory pathway, risking ventricular fibrillation and sudden death. Avoid AV nodal blockers like beta-blockers and calcium channel blockers.
2. Catheter ablation is the first-line rhythm control strategy in WPW. Catheter ablation carries a Class I recommendation and offers >90% success. If antiarrhythmic drugs are needed, sodium channel blockers like flecainide or propafenone are preferred in patients without structural heart disease.
3. In pregnancy, protecting the mother is protecting the fetus. An unstable mother means an unstable fetus. Rate control is the first step in AF with rapid ventricular responses and electrical cardioversion is safe when needed. Multidisciplinary care is essential.
4. AF in congenital heart disease is often outside the pulmonary veins. Surgical scars and chamber remodeling in ACHD patients often lead to AF from non-pulmonary vein foci. Electrogram-based mapping and targeted ablation strategies are essential to increase success rate of durable rhythm control.
5. Tachy-brady syndrome may require pacing to unlock therapy. AF may cause atrial myopathy and sinus node dysfunction. These patients often require permanent pacing to allow safe use of rate-controlling medications like beta-blockers and to prevent syncope or chronotropic incompetence.

Notes: Notes drafted by Dr. Yong Hao Yeo

Why is atrial tachycardia in patients with WPW syndrome dangerous?

• Patients with WPW commonly present with supraventricular tachycardia (SVT) due to atrioventricular reentrant circuits, either orthodromic or antidromic. This SVT can degenerate into AF.
• In the absence of AV nodal as the governor between the atrium and ventricles, the accessory pathway may conduct impulses rapidly and frequently. This can lead to dangerously high ventricular rates, predisposing patients to ventricular fibrillation and sudden cardiac arrest.

What are some strategies for rhythm control in patients with WPW and atrial tachycardia?

• Catheter ablation is the first-line therapy (Class I recommendation), with a success rate of over 90%.
• Ablation reduces the risk of sudden cardiac arrest, though some patients may remain prone to AF.
• If ablation is not feasible/ contraindicated, sodium channel blockers such as flecainide and propafenone are good options in patients without ischemia or structural heart disease (Class IIa recommendation).
• Amiodarone should be avoided because it has a long half-life, can accumulate in the system, and may delay definitive treatment with catheter ablation.
• AV nodal blocking agents like beta blockers and calcium channel blockers should be avoided, as they are less effective at controlling ventricular rate in WPW and can increase conduction over the accessory pathway. These agents can also exacerbate the risk of rapid ventricular rates during AF and worsen left ventricular function.

What are some special considerations in managing AF in pregnant patients?

• The primary goal in managing cardiovascular disease during pregnancy is to protect the mother, as fetal outcomes depend on maternal well-being. Therefore, while caution is necessary, we should avoid undertreating pregnant patients with AF.
• In cases of AF with rapid ventricular response (RVR), rate control is usually the first-line strategy, with beta blockers preferred over digoxin or non-dihydropyridine calcium channel blockers. It is then reasonable to initially observe for spontaneous conversion in stable patients.
• Antiarrhythmic drugs (AADs) are generally avoided during the first trimester, but clinical judgment on a case-by-case basis is essential.
• Evidence for the safety of AADs in pregnancy is limited, often derived from their use in other conditions such as fetal SVT. Flecainide and sotalol are reasonable options for rhythm control (Class IIa recommendation).
• Electrical cardioversion is considered safe in pregnancy and should be utilized when indicated (Do not forget!).
• There is no pregnancy-specific thromboembolic risk stratification tool. CHA₂DS₂-VASc scoring and the presence of risk factors like mitral stenosis can help guide anticoagulation decisions, though the magnitude of thromboembolic risk during pregnancy remains unclear.
• Rate control agents are typically continued during delivery due to the increased physiologic stress of labor and delivery.
• Multidisciplinary care is crucial and should involve obstetrics, maternal-fetal medicine, cardiology, and electrophysiology specialists.

What are some key considerations for AF management in patients with adult congenital heart disease (ACHD)?

• Patients with repaired congenital heart disease are at increased risk for arrhythmias due to two main factors: surgical scars that create arrhythmogenic foci and mechanical remodeling of the atria or ventricles resulting from the underlying disease.
  • In these patients with structural heart disease, sodium channel blockers may not be ideal antiarrhythmic options.
• When selecting an antiarrhythmic drug, clinicians must consider the nature of structural or surgical impairments, such as right bundle branch block or prolonged QT interval.
• It is also essential to assess renal and hepatic function (often impaired in patients with ACHD) to ensure appropriate metabolism and clearance of antiarrhythmic medications.
• Electrogram-based ablation strategies (those leveraging artificial intelligence are developing!) may help identify effective ablation targets, which are often outside the pulmonary veins in patients with ACHD. These individualized approaches can improve ablation success rates in this complex patient population.

What makes tachycardia-bradycardia (tach-brady) syndrome a unique challenge in arrhythmia management?

• Patients who present with both AF and bradycardia, especially with syncope, require a thoughtful diagnostic approach to identify the underlying rhythm disturbance.
• Extended cardiac monitoring, including event monitors or implantable loop recorders, can help capture intermittent arrhythmias and correlate them with symptoms.
• AF may lead to atrial myopathy, and since the sinus node resides within the atrium, this can result in sinus node dysfunction—a hallmark of tachy-brady syndrome.
• Following spontaneous conversion from AF to sinus rhythm, sinus node dysfunction may persist, leading to prolonged pauses or chronotropic incompetence.
• Management becomes more complex when beta-blockers are needed for AF with RVR, as they can exacerbate bradycardia. Permanent pacemaker implantation is often the next step to consider.
• Permanent pacemaker implantation is often considered to facilitate safe rate control in these cases.
• In younger patients, aggressive AF burden reduction may prevent atrial remodeling and the development of true atrial myopathy, potentially avoiding pacemaker implantation.

References

1. Joglar JA, Chung MK, Armbruster AL, et al. 2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2023;149(1). doi:https://doi.org/10.1161/CIR.0000000000001193 ‌
2. Van IC, Rienstra M, Bunting KV, et al. 2024 ESC Guidelines for the management of atrial fibrillation developed in collaboration with the European Association for Cardio-Thoracic Surgery (EACTS). European Heart Journal. 2024;45(36). doi:https://doi.org/10.1093/eurheartj/ehae176 ‌
3. Joglar JA, Kapa S, Saarel EV, et al. 2023 HRS expert consensus statement on the management of arrhythmias during pregnancy. Heart Rhythm. Published online May 1, 2023. doi:https://doi.org/10.1016/j.hrthm.2023.05.017 ‌
4. Stout KK, Daniels CJ, Aboulhosn JA, et al. 2018 AHA/ACC Guideline for the Management of Adults With Congenital Heart Disease: Executive Summary. Journal of the American College of Cardiology. 2019;73(12):1494-1563. doi:https://doi.org/10.1016/j.jacc.2018.08.1028 ‌