Feature Interview

Taking Efficiency to the Next Level: Advances in Cryoballoon Technology

Interview by Jodie Elrod

Interview by Jodie Elrod

In this feature interview, we speak with Dr. Marcin Kowalski and Dr. Arash Aryana about their use of the new Arctic Front Advance Pro Cryoballoon Catheter (Medtronic). Dr. Kowalski is the Director of Cardiac Electrophysiology and Associate Director of the Cardiology Fellowship Program at Staten Island University Hospital / Northwell Health System in Staten Island, New York. Dr. Aryana is the Medical Director of Cardiovascular Service Line at Mercy General Hospital / Dignity Health Heart and Vascular Institute in Sacramento, California. To date, Dr. Aryana has completed 45 AFA Pro cases and Dr. Kowalski has completed 20.

What is the Arctic Front Advance Pro Cryoballoon Catheter, and how it is different from the Arctic Front Advance Cryoballoon?

Kowalski: The Arctic Front Advance Pro Cryoballoon (AFA Pro) is the fourth generation of the Arctic Front family of cryoballoon catheters. The major improvement to the balloon was shortening of the tip by 40%, which allows the Achieve Mapping Catheter (Medtronic) to more frequently record PV potentials, in my opinion. There were also advancements made in the maneuverability and stability of the balloon.

Aryana: Unike its predecessor, the Arctic Front Advance (AFA) Cryoballoon, this fourth generation cryoballoon has an 8 mm distal tip, which is 5.5 mm shorter than the 13.5 mm tip of the AFA Cryoballoon, affording improved catheter maneuverability. Specifically, this catheter has been designed to greatly improve the ability to assess time to pulmonary vein isolation (PVI). Since the pulmonary vein (PV) potentials are typically recorded only within the proximal segments of the PVs where the sleeves are found, a shorter balloon tip can help markedly enhance the ability to record these PV potentials. A couple of years ago, we reported this finding alongside other investigators in the context of the third-generation cryoballoon and demonstrated that this feature significantly enhanced the procedural efficiency, resulting in shorter total procedure and fluoroscopy times.1 Additionally, time-to-isolation is an important predictor of procedural outcomes. It enables procedural workflow and efficiency, and also serves as the single most powerful predictor of PVI durability, both acutely and long term.2,3 Thus, the catheter’s enhanced ability to record time-to-isolation is very valuable. The internal design of the AFA Pro virtually mirrors that of the AFA Cryoballoon, which means that it likely preserves the biophysical behavior of that catheter. That is also very important, because much of the published literature so far regarding the biophysics of the cryoballoon pertains only to the Arctic Front Advance generation. Based on this, we should be able to assume that the biophysical behavior and performances of this catheter are not significantly altered.

Why is time-to-isolation an important metric, and why it is worth looking for?

Kowalski: Time-to-isolation became the most important factor in determining the dosing of cryo energy in each patient. It was found that time-to-isolation is the best predictor of outcome in numerous studies,3-5 including those performed by Dr. Aryana and myself. Proper dosing of the energy allows for best possible outcomes with least collateral damage to adjacent structures. Time-to-isolation allows us to individualize the energy delivered to each patient, while maximizing outcomes and minimizing collateral damage.

What does time-to-isolation tell us about the long-term quality of the lesion in particular?

Aryana: Not only is time-to-isolation an important predictor of acute PVI, but it’s also an important prognosticator of its long-term durability. Nearly 3 years ago, we conducted a study to investigate the procedural and biophysical characteristics associated with late PV reconnection versus durable PVI after AFA Cryoballoon ablation.3 What we found is that time-to-isolation of ≤60 seconds was the most powerful predictor of PVI durability as compared to all other procedural and biophysical variables. To give an idea: in this study, the area-under-the-ROC curve for predicting PVI durability at 14 months post-index ablation exceeded 0.90, suggesting that this variable is a very powerful predictor of this clinically relevant endpoint. We also found that during ablation, time-to-isolation correlated directly and very well with the magnitude of cryoballoon PV occlusion. Albeit a non-objective variable, as you may know, I consider it the gold standard when assessing the quality of a given cryoapplication.

How does this fit into your procedural usage of the balloon?

Kowalski: As we individualize the energy for each vein, we can minimize the length of the procedure without compromising outcomes, and we can predict durability of the lesion.

Aryana: I like using the AFA Pro Cryoballoon for my atrial fibrillation (AFib) cases, and I typically use this product with the 25 mm Achieve Advance Mapping Catheter (Medtronic), which gives me an excellent ability to record the PV potentials and assess time-to-isolation.

Tell us about your initial experience with the Arctic Front Advance Pro Cryoballoon. Are there any procedural differences (i.e., lab and fluoro times, usage and feel)?

Kowalski: I did not find much difference in the stability of the AFA Pro Cryoballoon during the procedure from the AFA Cryoballoon catheter. I was able to visualize time-to-isolation in 39 out of 40 PVs, and tailor the dose of cryo energy to each PV during the first 10 cases. Consequently, I was able to decrease the fluoro time as well as procedure time.

Aryana: It is important to note that the overall modifications made to the design of the AFA Pro Cryoballoon have not adversely impacted the catheter’s stability and/or maneuverability in the left atrium. In fact, I find this catheter to be quite stable and highly maneuverable in the atrium as a result of its shorter distal tip. In addition, we’ve noticed that the ability to record time-to-isolation is much improved using this catheter. In our experience thus far, it has been associated with a slight trend toward shorter procedure and even fluoroscopy times.

Can you be more specific about lab and fluoro times with this catheter?

Kowalski: Medtronic data from the European centers compares the AFA Cryoballoon to the AFA Pro Cryoballoon, and shows that the average procedure time was decreased by 13% and average fluoroscopy time was decreased by 15%. The decrease in fluoro and lab time is likely due to the ability of the new balloon to visualize time-to-isolation more often, as well as tailor the length and number of cryo application per vein. Many studies have shown that using time-to-isolation as a guide shortens the procedure time without sacrificing outcomes.2,5

Has there been a learning curve from your initial experience to more recent cases?

Kowalski: The learning curve, especially for new users, is not as steep as for AFib ablation performed using radiofrequency. The shorter tip may also allow for more flexibility of the balloon to obtain more antral occlusion.

Aryana: Yes, the learning curve is rather gentle. I should point out that some users in the past have suggested that the absence of a longer catheter tip might interfere with the balloon positioning and possibly even hinder its stability at the PV antra, particularly when used in conjunction with the softer Achieve Advance. In our experience, this is rarely encountered. However, the operator should certainly remain cognizant of this issue. Overall, I would say we have found the AFA Pro Cryoballoon to be better and superior to the AFA Cryoballoon for the previously stated reasons.

What should a new user to the Arctic Front Advance Pro Cryoballoon understand about handling, usage, and maneuvers, to have immediate success with this balloon?

Kowalski: There are a few things that are very important to remember when using the AFA Pro Cryoballoon. First, contact is most important — no matter what generation of the cryoballoon they are using. It’s imperative to obtain complete occlusion of the PV and adequate contact of the balloon to the cardiac tissue. When occlusive PVI is the goal, circumferential contact is key to delivering an effective lesion. In case of large common ostium or ovoid vein, the balloon can effectively segment the vein to create PVI. Second, it is important to pull back the Achieve catheter to the PV ostium and record PV potential. Once the potentials are visualized, the operator should base their dosing protocol on time-to-isolation. Third, it is also important to pull the entire balloon inside the sheath and extend the Achieve Catheter outside the sheath while moving the cryoballoon from the left- to right-sided PV to prevent perforation. In addition, it is imperative to prevent ablating inside the PV and keep the cryoballoon as antral as possible, thereby achieving a lesion set with closer resemblance to the typical wide area circumferential ablation. The proximal seal technique is a useful method to assess the location of the balloon in relation to the PV ostium.

What feedback have you received from your staff?

Aryana: They too have noticed the improved time-to-isolation visualization ability. We are also seeing a clear trend toward shorter procedure and fluoroscopy times, which are likely a direct consequence of it.

Kowalski: My staff appreciates the predictable procedure time associated with cryoballoon ablation. The reduction of procedure duration variability is an important factor in determining workflow in the EP lab. Multicenter studies have also translated the economic value of shorter procedure times and reduced variability of procedure duration associated with the cryoballoon procedure.6,7 The benefits of the cryoballoon procedure demonstrated in the studies included more days where staff overtime is avoided, less cumulative overtime hours, and more days with time left for additional EP lab usage. 

Disclosures: Dr. Aryana reports consulting fees from Medtronic specific to AFA Pro; outside the submitted work, he reports a research grant, consulting, and speaker honoraria from Medtronic. Dr. Kowalski reports consulting fees from Medtronic specific to AFA Pro. The views expressed in this article are representative of those held by the physicians interviewed, and not of Medtronic.

This article is published with support from Medtronic.

References
  1. Aryana A, Kowalski M, O’Neill PG, et al. Catheter ablation using the third-generation cryoballoon provides an enhanced ability to assess time to pulmonary vein isolation facilitating the ablation strategy: short- and long-term results of a multicenter study. Heart Rhythm. 2016;13:2306-2313.
  2. Aryana A, Kenigsberg DN, Kowalski M, et al. Verification of a novel atrial fibrillation cryoablation dosing algorithm guided by time-to-pulmonary vein isolation: results from the Cryo-DOSING Study (Cryoballoon-ablation DOSING Based on the Assessment of Time-to-Effect and Pulmonary Vein Isolation Guidance). Heart Rhythm. 2017;14:1319-1325.
  3. Aryana A, Mugnai G, Singh SM, et al. Procedural and biophysical indicators of durable pulmonary vein isolation during cryoballoon ablation of atrial fibrillation. Heart Rhythm. 2016;13:424-432.
  4. Ciconte G, de Asmundis C, Sieira J, et al. Single 3-minute freeze for second-generation cryoballoon ablation: one-year follow-up after pulmonary vein isolation. Heart Rhythm. 2015;12:673-680.
  5. Chun JK, Stich M, Fürnkranz A, et al. Individualized cryoballoon energy pulmonary vein isolation guided by real-time pulmonary vein recordings, the randomized ICE-T trial. Heart Rhythm. 2017;14:495-500.
  6. Kowalski M, DeVille JB, Svinarich JT, et al. Using discrete event simulation to model the economic value of shorter procedure times on EP lab efficiency in the Value PVI Study. J Invasive Cardiol. 2016;28:176-182.
  7. DeVille JB, Svinarich JT, Dan D, et al. Comparison of resource utilization of pulmonary vein isolation: cryoablation versus RF ablation with three-dimensional mapping in the Value PVI Study. J Invasive Cardiol. 2014;26:268-272.
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