In this feature interview, we speak with Prof. Karl-Heinz Kuck, MD, director of cardiology at Asklepios Klinik St. Georg in Hamburg, Germany, about his first case using the Arctic Front Advance® ST Cryoballoon (Medtronic, Inc.), which recently received FDA approval for the treatment of drug refractory, recurrent, symptomatic paroxysmal atrial fibrillation (AF). It is indicated for the treatment of atrial fibrillation in Europe. This product will be broadly available to physicians in fall 2015 following a limited market release.
Tell us about your program at Asklepios Klinik St. Georg. Approximately how many cryoablation cases do you perform annually?
Undoubtedly with the rapidly growing number of people suffering from atrial fibrillation, we are already in the midst of a silent epidemic. In the cath labs of our clinic, approximately 2,300 patients suffering from heart rhythm disorders are treated each year. By using the latest innovative technologies, the Asklepios Klinik St. Georg in Hamburg is one of the leading and largest centers worldwide. We have had the opportunity to use the cryoballoon technology since its inception a decade ago. We perform over 200 cryoballoon procedures per year.
Tell us about your use of the new third-generation Arctic Front Advance ST Cryoballoon catheter thus far.
Just before the Heart Rhythm 2015 congress, we completed the first Arctic Front Advance ST procedures worldwide in our lab in Hamburg. Our experience with the new cryoballoon ablation system so far has been limited, but I can already say that the third-generation cryoballoon offers the potential for more real-time data and even better maneuverability, which may further enhance the procedure and its outcome for the patients’ benefit.
How does the third-generation Arctic Front Advance ST Cryoballoon catheter differ from its previous generation models?
The Arctic Front Advance ST Cryoballoon builds upon the proven performance of the Arctic Front Advance System. Among the enhancements we see is a shorter distal tip, which is designed in response to physicians’ needs in a real-world, clinical setting. It is too early to say, but the shorter tip could make it easier to visualize pulmonary vein (PV) recordings and individualize ablation strategies.
What are the components of the Arctic Front Advance System?
The main components of the cryoballoon system include the Arctic Front Advance cardiac cryoablation catheter, which is meant to occlude each of the PVs and for the application of cold to isolate the pulmonary veins. The FlexCath Advance steerable sheath has been specifically designed for use with the Arctic Front Advance, and enables the user to approach the PVs with an ease of access and maneuverability. The Achieve mapping catheter provides the operator with valuable real-time data during the procedure. The Cryoconsole acts as the brain of the system, controlling the safe and efficient delivery of nitrous oxide to the catheter.
When did Asklepios Klinik St. Georg begin using the Arctic Front Advance System? What prompted you to start using cryo as an energy source for ablation?
We started using the cryoballoon back in 2006 when point-by-point RF ablation was the gold standard in AF ablation. RF ablation was technically challenging and associated with a long learning curve — it is still a challenge to create transmural, contiguous and durable lesions. The cryoballoon is a minimally invasive, anatomically designed catheter made specifically to simplify pulmonary vein isolation (PVI). Already with the development of the Arctic Front, the first-generation cryoballoon, I saw the potential this single shot technology presented in terms of efficiency and reproducibility of outcomes. Today, cryoballoon ablation is used worldwide as a standard in catheter AF ablation, as recognized by the latest 2012 EHRA/HRS consensus document.
Describe the cases in which you are using the Arctic Front Advance ST Cryoballoon catheter.
For our index procedures, PVI is the key element for paroxysmal as well as for persistent AF. We do not use pre-procedural imaging such as cardiac MRI or cardiac CT to guide technology use. On the first day, we treated three patients with the Arctic Front Advance ST: two suffering from paroxysmal, and one from persistent AF. We were able to isolate all pulmonary veins with only 1.45 applications on average. The average procedure and fluoroscopy times were 71 minutes and 18 minutes, respectively. Real-time PV potential registration was possible in 72% of the veins; in these cases, time-to-isolation averaged 46 seconds.
How does the catheter help gauge ablation success in real-time in the clinical setting?
Assessment of the exact time of PVI may improve the understanding of cryoballoon lesion formation and enhance procedural efficacy. As an outcome, it directly ensures an impressive safety profile using this technology. Published evidence suggests that time to isolation is a predictor of durable PV isolation and predictor of arrhythmia recurrence during follow-up. As a result, this intraprocedural information can be used to optimize the patient outcome and safety profile.
How much of your ablation practice is cryo? What makes cryo an ideal ablation source?
We now use this therapy in about 30% of our index procedures for paroxysmal AF, and increasingly for persistent AF as well. Cryoablation is different, which can be explained by the unique mechanisms of cryothermal injury. Cryoablation lesions are well-circumscribed discrete lesions with sharp borders, dense areas of fibrotic tissue, and contraction band necrosis. From existing clinical data, this appears to be the reason for very limited post-procedural tachycardias. In treating our patients with atrial fibrillation, we need to ensure that we do not move them to other and sometimes more complex tachycardias. Cryoablation leads with a wave of hypothermia, allowing for periprocedural adjustments.
What is your method for follow-up?
Our routine clinical follow-up includes outpatient clinic visits at 1, 3, 6 and 12 months after ablation, followed by 12-month intervals. In case of symptoms suggestive for atrial arrhythmia recurrences, additional outpatient clinic visits are initiated. Additionally, patients can be equipped with an external or internal event recorder if necessary.
Is there anything else you'd like to add?
With the growing epidemic of atrial fibrillation, I think it should be our mission to further develop curative strategies for its treatment through clinical expertise and technological innovations such as the cryoballoon as a contributing factor.
Disclosure: The author has no conflicts of interest to report regarding the content herein. Outside the submitted work, Dr. Kuck reports grants and lecture fees from St. Jude Medical, Medtronic, and Biosense Webster.