Management of Arrhythmias after Ablation of Atrial Fibrillation

Joseph Akar, MD, MRCP, FACC, Division of Cardiology, Yale University School of Medicine; Mithilesh K Das, Associate Professor of Clinical Medicine, Krannert Institute of Cardiology, Chief, Cardiac Electrophysiology, Roudebush VA Medical Center, Indiana University School of Medicine; Bradley P Knight, MD, FACC, Professor of Internal Medicine-Cardiology, University of Chicago

Dr. Knight explained before this session that it was intended to be as informal as possible; he told attendees to feel free to interrupt with the supplied microphones, which only a couple people took advantage of, one perhaps a bit too aggressively.

Dr. Das began with a review of post-atrial fibrillation (AF) ablation for atrial tachycardia (AT). He explained that the prevalence of AT/AF is based on initial AF ablation therapy, and that the recurrent of AT/AF after catheter ablation jumps from 15% to 45% within days. Moving very quickly through his presentation, the speaker next noted that structural heart disease patients have a higher recurrence (74%) of these conditions. Other key points he made were as follows:

• Class IC and Class III anti-arrhythmic drugs (AADs) are typically used in first 6 weeks of treatment with these patients. In the 5A study, AAD use during the 6 weeks after ablation reduces AT/AF by 50%. Withdrawal of AAD therapy may lead to recurrence; if it does, reinitiate ADD therapy or consider catheter ablation.
• Repeat procedures should be delayed for at least 3 months after initial ablation or if the patient is "very symptomatic."
• In AT after catheter ablation, there is a 10% incidence of recurrent arrhythmias, with most originating in the left atrium (LA).
• When looking at sites of arrhythmias, the following most often holds true: they are focal mostly after PAF ablation and of the reentry type when occurring in the pulmonary vein, left atrium roof, posterior wall, septum, and coronary sinus.
• An isoelectric line between P waves favors Focal AT, as does a >15% cycle length variation.
• Always start from the right side when looking at entrainment from the superior vena cava-right atrium junction.
• You can ablate from anywhere and still detect tachycardia within the circuit.
• If AT is focal, map the earliest activation.
• It is easier to ablate when the central line is stable; this has a 90% success rate.
• It is of critical importance to distinguish between focal and reentrant AT.
• Entrainment helps, but there is a risk of termination of AT or initiation of another AT.

Knight continued the session, saying to approach cases of these conditions by paying careful attention to what was done before-what techniques were used in a previous ablation and if the patient has had cardiac surgery. He focused first on a case of a 61-year-old woman with atrial fibrillation 5 months after pulmonary vein isolation (PVI) and cavotricuspid isthmus (CTI) ablation. The cardiology team on the case excluded the right atrium first. He explained that "once you're in the left atrium, inspect all pulmonary veins and exclude those that can be, exclude the left atrial appendage, and exclude the roof."

In this case study, after several lesions along the roof and no slowing of termination, the cardiologists had to re-isolate PVs. "If you're not making progress," said Knight, "re-evaluate the mechanism of the tachycardia." In this case, the proposed mechanism was a figure of 8 reentry around the mitral annulus and left PVs.

Knight next showed a video clip that displayed the effect of manual color scale adjustment. He advised to always adjust the color to expand them. In the case study, they were able to see what appeared as micro-reentry as opposed to what they thought was focal with a limited color scale.

Knight closed his section of the session with a case of atrial tachycardias after RFA ablation for AF. He explained that it is more practical to bring a patient into the lab when they are having a tachycardia, even if it means having them sit in the hospital for a day.

Dr. Akar, quite possibly the fastest speaker on the planet (maybe because he only had 12 minutes to speak), closed the session. Blazing through, he made the following key points:

• The LA structure lends itself to arrhythmias, with more veins with muscular sleeves, two isthmuses, and wider and thicker isthmus tissue.
• Features consistent with LA origin include: Distal to proximal activation in the CSEarliest activation < 30 ms pre P wave.Early activation along Bachman's bundle, septum or CS ostium with fusion of wavfronts on the later wall.
• Features of the macrorentrant circuits include: Entraiment from multiple regions.An ability to map > 90% tachycardia cycle length. Insensitivity to adenosine

In closing, Akar advies to perform entrainment mapping from multiple sites but be mindful of its limitations, use entrainment mapping to define macroreentrant circuits, consider other circuits if the cycle length changes, Don't learn as you burn by always defining the circuits, target the site of earliest activation for focal AT, and target the critical isthmus for macroreentrant circuits.