Abstract
Background
The novel Polarx™ cryoablation system is currently being studied for atrial fibrillation (AF) ablation. To the best of our knowledge, no study comparing the novel cryoablation system with the standard Arctic Front™ cryoballoon is available in today’s literature. This study aims to compare Polarx™ and Arctic Front™ cryoballoon in terms of safety and efficacy.
Methods
From a total cohort of 202 patients who underwent pulmonary vein (PV) isolation for paroxysmal AF through cryoablation, a population of 30 patients who used Polarx™ were compared with 30 propensity-score matched patients who used Arctic Front™.
Results
Pulmonary vein occlusion and electrical isolation were achieved in all (100%) veins with a mean number of 1.09 ± 0.3 occlusion per vein using Polarx™ and 1.19 ± 0.5 occlusion per vein using Arctic Front™ (p = 0.6). Shorter procedure and fluoroscopy time were observed with Polarx™ group (60.5 ± 14.23 vs 73.43 ± 13.26 mins, p = 0.001; 12.83 ± 6.03 vs 17.23 ± 7.17 mins, p = 0.01, respectively). Lower cumulative freeze duration per vein was also observed with Polarx™ (203.38 ± 72.03 vs 224.9 ± 79.35 mins, p = 0.02). There was no significant difference in isolation time between the two groups (34.47 ± 21.23 vs 34.18 ± 26.79 secs, p = 0.9).
Conclusions
The novel Polarx™ cryoablation system showed similar efficacy in vein occlusion and isolation and safety profile when compared to Arctic Front™ cryoablation system. Procedure time, fluoroscopy time, and cumulative freeze duration were significantly lower with Polarx™ cryoablation system.
Keywords: Atrial fibrillation, Cryoballoon, Arctic Front, Polarx
Introduction
The pulmonary veins (PV) play a key role in the pathogenesis of atrial fibrillation (AF) and their isolation is associated with freedom from AF 1. PV isolation using catheter ablation is achieved through different sources (laser, radiofrequency, cryoenergy) and is being increasingly performed worldwide. Cryoablation has high efficacy in isolating PVs, low rate of complications, more reproducible and less operator dependent outcomes, and is proven superior to antiarrhythmic drugs (AADs) in preventing AF recurrence 2-4, making it standard of care for numerous institutions for AF management. Over the years, Arctic Front™ cryoballoon (Medtronic, USA) has been paving the way for the science of AF cryoablation 5-9. The Polarx™ cryoablation system (Boston Scientific, USA) has been very recently released on the market, with modifications designed to potentially improve workflow for PV isolation. The present study aimed to compare the safety and efficacy of the new Polarx™ cryoablation system with the standard Arctic Front™ cryoablation system.
Aim of the study
The aim of the study was to compare the new Polarx™ cryoablation system with the standard Arctic Front™ cryoballoon in terms of safety and efficacy during PV isolation for AF.
Methods
Study Population. All patients who underwent PV isolation for paroxysmal AF using Polarx™ cryoablation system and Arctic Front™ cryoablation system from March 2 to October 16, 2020 were included in this study. The study was retrospective in nature and approved by the local ethics committee of our institution. All patients underwent cryoablation procedure with standard protocol in our institution.
Preprocedural management. All patients provided written informed consent to the ablation. A transthoracic echocardiogram (TTE) was performed one week prior to ablation for assessment of structural heart disease. To exclude the presence of thrombi, transesophageal echocardiography (TEE) was performed on the day of the procedure. All patients underwent pre-procedural cardiac computed tomography (CT) scan to assess left atrium (LA) and PV anatomy. The LA anteroposterior diameter was assessed by TTE on parasternal long-axis M mode and indexed to body surface area. Antiarrhythmic drugs (AAD) were discontinued at least 3 days before the scheduled ablation.
Polarx™ cryoablation system. The novel cryoablation system is composed of a Polarx™ cryoballoon (Boston Scientific, USA) that is maneuvered in the left atrium through a steerable sheath (PolarSheath™, Boston Scientific, USA). An inner-lumen mapping catheter (ILMC) (PolarMap™, Boston Scientific, USA) is placed inside the cryoballoon inner lumen and positioned in the ostium of each PV. The system is connected to a console (SmartFreeze™, Boston Scientific, USA) which controls, monitors, and records the different phases of cryoablation (inflation, freezing, deflation). For this study, we used the short-tip Polarx™ cryoballoon catheter. See [Figure 1] for Polarx™ cryoablation system.
Figure 1. Cross section of the novel POLARx™ cryoballoon catheter, showing integral parts of the balloon catheter. Image courtesy of Boston Scientific.
Arctic Front™ cryoablation system. The standard cryoablation system is composed of the Arctic Front Advance Pro™ cryoballoon catheter (Medtronic, USA) that is maneuvered in the left atrium through a steerable sheath (FlexCath Advance™, Medtronic, USA). An ILMC (Achieve™ mapping catheter, Medtronic, USA) is placed inside the cryoballoon inner lumen and positioned in the ostium of each PV. The system is connected to a console (CryoConsole™, Medtronic, USA) which controls, monitors, and records the different phases of cryoablation. See [Table 1] for description and difference between the 2 cryoablation systems. See [Figure 2] for Arctic Front™ cryoablation system.
Table 1. Description and difference between Polarx™ and Arctic Front™ cryoablation system.
| Polarx™ | Arctic Front™ | |
|---|---|---|
| Cryoballoon | Polarx™ Diameter: 28mm | Arctic Front Advance Pro™ Diameter: 28mm |
| Steerable sheath | PolarSheath™ 155º deflection | FlexCath™ 135º deflection |
| Mapping Catheter | Polarmap™ Diameter: 20mm Electrode: 8 | Achieve Advance™ Diameter: 25mm Electrodes: 10 |
| console | SmartFreeze™ Foot pedal option Diaphragm movement sensor | CryoConsole™ |
Figure 2. Cross section of the Arctic Front™ cryoballoon catheter, showing integral parts of the balloon catheter. Image courtesy of Medtronic.
Cryoballoon ablation procedure. All procedures were done by two primary operators who both performed more than 1,000 Arctic Front cryoballoon each. Procedures were performed under general anesthesia. Under TEE guidance, an 8.5-Fr transeptal sheath (SL-0, Abbott) with a Brockenbrough needle (BRK-1, Medtronic) was advanced to the LA and exchanged for the cryoballoon steerable sheath. The cryoballoon and ILMC were advanced in each PV ostium to obtain baseline electrical information. The cryoballoon was inflated and gently advanced to occlude each PV. Pulmonary vein occlusion was assessed with contrast injection. Optimal vessel occlusion is when contrast injection showed total contrast retention inside the PV with no backflow to the LA. Activated clotting time was maintained at 250 seconds by an initial intravenous bolus of heparin with supplemental heparin boluses as required. Protamine was administered after the procedure and manual pressure was applied on the access site after removal of sheath and catheters.
Assessment of electrical isolation. Pulmonary vein electrical isolation was recorded with the ILMC positioned at the proximal site in the ostium before cryoablation of each PV. If PV potentials were visible during cryoablation, time to isolation (TTI) was recorded when PV potentials disappear or were dissociated from LA electrical activity. If PV potentials were not visible during ablation due to a distal positioning of the ILMC, the latter was retracted after completion of the cryoablation to a more proximal position to examine the PV potentials.
Duration of cryoenergy application. A single 180-second application was delivered for each vein with TTI or temperature of less than -40 ºC within one minute of cryoablation, otherwise a bonus freeze was delivered. Cryoablation was immediately terminated if there was weakening of diaphragmatic contraction.
Phrenic nerve monitoring. Right phrenic nerve function was monitored during right-sided PV cryoablation by locating and pacing the right phrenic nerve with a 1200-ms cycle and 20-mA output. The diaphragmatic capture was monitored by the operator’s hand on the patient’s abdomen for both Arctic Front™ and Polarx™ cryoablation and through the diaphragmatic movement sensor (DMS) accelerometer attached on the patient’s right upper abdomen for the Polarx™ cryoablation. Cryoablation was terminated when weakness of diaphragmatic movement was noted.
Post ablation management. Patients were admitted in the intensive care unit and continuously monitored with electrocardiogram (ECG) telemetry for at least 18 hours. Post-procedure lower extremity ultrasound and TTE were performed the day after the procedure to assess complications such as pseudoaneurysm, hematoma, cardiac structural damage, or pericardial effusion. If without complication, patients were discharged the day after the procedure. Oral anticoagulation was resumed on the evening of the procedure and continued for at least 3 months.
Statistical Analysis
Continuous variables were expressed as mean ± standard deviation (SD) and significant differences were analyzed by Student t-test. Categorical data were expressed as number and percentages and compared by Chi square test. Propensity-score matching was performed in order to compare the outcome between Arctic Front™ group and Polarx™ group. Patients were matched in a 1:1 ratio based on propensity scores calculated for each patient using multivariable logistic regression based on age, gender, CHA2DS2VASc score, and presence of LA dilatation (LAVi >34 ml/m2) as covariates. A 2-tailed probability value of <0.05 was deemed significant. Statistical analyses were conducted using SPSS software (SPSS version 27, Armonk, NY, USA).
Results
Baseline characteristics. A total of 202 consecutive patients with paroxysmal AF underwent cryoablation and were included in our study. Thirty patients who underwent cryoablation using Polarx™ and 172 using Arctic Front™ were included in the matching process. Of that cohort, all the 30 Polarx™ patients were matched to 30 Arctic Front™ patients in a 1:1 ratio based on propensity scores which resulted in two balanced groups. [Table 2] shows baseline characteristics of the matched patients.
Table 2. Baseline characteristics.
Data presented as N (%) or mean ± SD; AF, atrial fibrillation
| Polarx™ (N, 30) | Arctic Front™ (N, 30) | P value | |
|---|---|---|---|
| Gender, male | 20 (66) | 18 (60) | 0.5 |
| Age, years | 57.47 ± 15.24 | 53.53 ± 16.24 | 0.3 |
| Hypertension | 10 (33) | 9 (30) | 0.7 |
| Dyslipidemia | 9 (30) | 8 (26) | 0.7 |
| Diabetes | 1 (3) | 2 (6) | 0.5 |
| Heart failure | 3 (10) | 1 (3) | 0.3 |
| Coronary artery disease | 1 (3) | 3 (10) | 0.3 |
| Prior embolic event | 0 | 1 (3) | 0.3 |
| Left atrium volume index | 31.5 ± 8.23 | 31.87 ± 7.31 | 0.8 |
| CHA2DS2VASc score | 1.27 ± 1.33 | 1.13 ± 1.40 | 0.7 |
Procedural characteristics. The matched 60 patients underwent PV isolation by cryoablation using either Arctic Front™ cryoablation system or Polarx™ cryoablation system. Acute PV isolation was achieved in all veins (100%) without the need for additional focal catheter application. No significant difference was found in total cryoballoon applications with Polarx™ and Arctic Front™ (1.09 ± 0.3 vs 1.19 ± 0.5, p = 0.6). Significant differences were found in procedure and fluoroscopy time when comparing Polarx™ and Arctic Front™ (60.5 ± 14.23 vs 73.4 ± 13.26 mins, p = 0.001; 12.83 ± 6.03 vs 17.23 ± 7.17 mins, p = 0.01). There was no significant difference in amount of contrast used with Polarx™ and Arctic Front™ (62.17 ± 7.84 vs 60.17 ± 8.03 mL, p = 0.9). There was also significant difference in cumulative freeze duration in both groups (203.38 ± 72.03 vs 224.9 ± 79.35, p = 0.02). For all PVs that underwent cryoballoon applications between Polarx™ and Arctic Front™, there were significant differences in time to reach 0 ºC (13.76 ± 2.11 vs 10.69 ± 1.66 secs, p < 0.001), time to reach -40ºC (30.43 ± 12.53 vs 47.96 ± 16.91 secs, p < 0.001), temperature at 60 seconds (-51.57 ± 5.09 vs -42.87 ± 4.41 ºC, p < 0.001), nadir temperature (-58.13 ± 6.26 vs -49.63 ± 6.19 ºC, p < 0.001), thaw time to 0 ºC (19.31 ± 7.9 vs 10.0 ± 4.13 secs, p < 0.001) and isolation temperature (-35.5 ± 13.36 vs -29.58 ± 11.27 ºC, p < 0.002). There was no significant difference in isolation time between the two groups (34.47 ± 21.23 vs 34.18 ± 26.79 secs, p = 0.9). When performing head-to-head analysis using Student t-test, comparing the Polarx™ and Arctic Front™ for each vein, no significant differences were found for isolation temperature of the left inferior pulmonary vein (LIPV) (-29.52 ± 11.83 vs -25.28 ± 11.17 ºC, p = 0.2), right superior pulmonary vein (RSPV) (-31.71 ± 12.07 vs -26.75 ± 10.65 ºC, p = 0.1) and right inferior pulmonary vein (RIPV) (-35.64 ± 14.21 vs -30.35 ± 7.88 ºC, p = 0.1). Electrical activity visualization enabling real time isolation was significantly different between Polarx™ and Arctic Front™ (84% vs 70%, p = 0.009). [Table 3] and [Table 4] show procedural and cryoablation characteristics of the matched patients.
Table 3. Procedural characteristics.
Data presented as N (%) or mean ± SD
| Polarx™ (N, 30) | Arctic Front™ (N, 30) | P value | |
|---|---|---|---|
| Procedure duration, minutes | 60.50 ± 14.23 | 73.43 ± 13.26 | 0.001 |
| Fluoroscopy duration, minutes | 12.83 ± 6.03 | 17.23 ± 7.17 | 0.01 |
| Contrast used, mL | 62.17 ± 7.84 | 60.17 ± 8.03 | 0.9 |
| Phrenic Nerve Injury | 1 (3) | 1 (3) | 1.0 |
Table 4. Cryoablation characteristics.
Data presented as N (%) or mean ± SD. LSPV, left superior pulmonary vein; LIPV, left inferior pulmonary vein; RSPV, right superior pulmonary vein; RIPV, right inferior pulmonary vein
| Polarx™ (N, 30) | Arctic Front™ (N, 30) | P value | |
|---|---|---|---|
| LSPV | |||
| Number of occlusion | 1.17 ± 0.46 | 1.07 ± 0.25 | 0.3 |
| Cumulative freeze duration | 225.13 ± 112.86 | 214.0 ± 78.28 | 0.65 |
| Time to 0ºC, seconds | 15.0 ± 1.53 | 11.93 ± 1.68 | < 0.001 |
| Time to -40ºC, seconds | 30.7 ± 4.35 | 44.17 ± 10.71 | < 0.001 |
| Temperature at 60 secs, ºC | -52.33 ± 4.17 | -45.0 ± 4.25 | < 0.001 |
| Nadir temperature, ºC | -57.7 ± 5.42 | -52.8 ± 4.57 | < 0.001 |
| Real time isolation | 27 (90%) | 22 (73%) | 0.09 |
| Isolation time, seconds | 43.81 ± 19.30 | 48.43 ± 39.98 | 0.6 |
| Isolation temperature, ºC | -44.3 ± 10.6 | -35.50 ± 12.59 | 0.01 |
| Thaw time to 0ºC, seconds | 19.34 ± 6.92 | 11.50 ± 4.01 | < 0.001 |
| LIPV | |||
| Number of occlusion | 1.0 ± 0 | 1.27 ± 0.64 | 0.02 |
| Cumulative freeze duration | 180.43 ± 19.76 | 249.07 ± 91.78 | < 0.001 |
| Time to 0ºC, seconds | 13.27 ± 2.28 | 10.47 ± 1.54 | < 0.001 |
| Time to -40ºC, seconds | 33.30 ± 14.0 | 54.93 ± 22.37 | < 0.001 |
| Temperature at 60 secs, ºC | -49.90 ± 5.24 | -41.0 ± 4.22 | < 0.001 |
| Nadir temperature, ºC | -55.33 ± 5.96 | -45.37 ± 6.86 | < 0.001 |
| Real time isolation | 25 (83%) | 18 (60%) | 0.04 |
| Isolation time, seconds | 26.24 ± 9.65 | 26.11 ± 18.56 | 0.9 |
| Isolation temperature, ºC | -29.52 ± 11.83 | -25.28 ± 11.17 | 0.2 |
| Thaw time to 0ºC, seconds | 17.71 ± 5.99 | 8.63 ± 3.8 | < 0.001 |
| RSPV | |||
| Number of occlusion | 1.13 ± 0.34 | 1.23 ± 0.62 | 0.4 |
| Cumulative freeze duration | 205.9 ± 71.31 | 214.27 ± 78.5 | 0.6 |
| Time to 0ºC, seconds | 13.4 ± 2.41 | 10.07 ± 1.31 | < 0.001 |
| Time to -40ºC, seconds | 30.53 ± 13.7 | 43.74 ± 15.0 | 0.001 |
| Temperature at 60 secs, ºC | -52.47 ± 5.72 | -43.83 ± 4.52 | < 0.001 |
| Nadir temperature, ºC | -59.67 ± 6.83 | -51.77 ± 5.66 | < 0.001 |
| Real time isolation | 24 (80%) | 24 (80%) | 1.0 |
| Isolation time, seconds | 32.83 ± 28.64 | 24.96 ± 13.97 | 0.2 |
| Isolation temperature, ºC | -31.71 ± 12.07 | -26.75 ± 10.65 | 0.1 |
| Thaw time to 0ºC, seconds | 20.81 ± 10.36 | 10.36 ± 4.76 | < 0.001 |
| RIPV | |||
| Number of occlusion | 1.07 ± 0.25 | 1.20 ± 0.4 | 0.1 |
| Cumulative freeze duration | 202.07 ± 45.13 | 222.27 ± 65.38 | 0.1 |
| Time to 0ºC, seconds | 13.37 ± 1.69 | 10.33 ± 1.51 | < 0.001 |
| Time to -40ºC, seconds | 27.2 ± 14.91 | 49.28 ±16.0 | < 0.001 |
| Temperature at 60 secs, ºC | -52.0 ± 4.92 | -41.57 ± 3.62 | < 0.001 |
| Nadir temperature, ºC | -58.83 ± 6.17 | -48.60 ± 4.73 | < 0.001 |
| Real time isolation | 25 (83%) | 20 (66%) | 0.1 |
| Isolation time, seconds | 34.16 ± 20.58 | 36.95 ± 20.38 | 0.6 |
| Isolation temperature, ºC | -35.64 ± 14.21 | -30.35 ± 7.88 | 0.1 |
| Thaw time to 0ºC, seconds | 19.41 ± 7.93 | 9.52 ± 3.52 | < 0.001 |
| Total | |||
| Number of occlusion | 1.09 ± 0.3 | 1.19 ± 0.5 | 0.6 |
| Cumulative freeze duration | 203.38 ± 72.03 | 224.9 ± 79.35 | 0.02 |
| Time to 0ºC, seconds | 13.76 ± 2.11 | 10.69 ± 1.66 | < 0.001 |
| Time to -40ºC, seconds | 30.43 ± 12.53 | 47.96 ± 16.91 | < 0.001 |
| Temperature at 60 secs, ºC | -51.67 ± 5.09 | -42.87 ± 4.41 | < 0.001 |
| Nadir temperature, ºC | -58.13 ± 6.26 | -49.63 ± 6.19 | < 0.001 |
| Real time isolation | 101 (84%) | 84 (70%) | 0.009 |
| Isolation time, seconds | 34.47 ± 21.23 | 34.18 ± 26.79 | 0.9 |
| Isolation temperature, ºC | -35.5 ± 13.36 | -29.58 ± 11.27 | 0.002 |
| Thaw time to 0ºC, seconds | 19.31 ± 7.9 | 10.0 ± 4.13 | < 0.001 |
Complications. There was no significant difference between Polarx™ and Arctic Front™ groups in terms of complications. The most frequent complication noted was transient right-sided phrenic nerve palsy, with incidence of 3% in the Polarx™ group and 3% in the Arctic Front™ group (p = 1.0). Diaphragm weakness was noted in 1 RSPV application in the Polarx™ group, and 1 RSPV application in the Arctic Front™ group. Diaphragm contraction completely recovered during the same procedure. No lower extremity hematoma, pericardial effusion, cerebrovascular accident, or cardiac structural damage were noted.
Discussion
To the best of our knowledge, this is the first study comparing the acute efficacy and safety outcome of Polarx™ cryoablation system with Arctic Front™ cryoablation system. The main findings were: (1) PV isolation with either Polarx™ or Arctic Front™ cryoablation system provided acute isolation in 100% of all PVs, (2) Polarx™ was associated with shorter procedure and fluoroscopy time, (3) in all PVs, Polarx™ showed slower time to reach 0º, faster time to reach -40ºC, lower temperature at 60 seconds, lower nadir temperature, longer thaw time to 0 ºC, shorter cumulative freeze duration, and no significant difference in time to isolation, and (4) there were no difference in procedure-related complications between the 2 groups. Optimal placement and contact with the PV ostium are important in creating a well-defined cryothermal lesion. Diminished contact between the cooling zone and PV ostium can lead to gaps and PV electrical reconnection. Several modifications in Arctic Front™‘s cryoballoon design over the years have led to a larger ablation area 10-16. In our study, adequate occlusion during contrast administration and eventual isolation were achieved in all PVs (100%) with no significant difference between the number of cryoballoon applications per vein between Polarx™ and Arctic Front™. While Polarx™ theoretically presents with more stable balloon positioning due to its uniform size and pressure throughout all cryoablation phases (inflation, freezing, thawing), there was no significant difference with the number of occlusions per vein to achieve isolation when using either Polarx™ or Arctic Front™ cryoablation system. In assessing number of occlusions as a measure of learning curve, the nonsignificant difference is probably due to the large experience accumulated during the years by our operators in performing cryoballoon ablation with the Arctic Front™. Duration of procedure and fluoroscopy time was significantly shorter with Polarx™ when compared to Arctic Front™. Shorter procedure time may be partly due to the inherent set-up of the Polarx™ console where the main steps of inflation, freezing, and deflation are all controlled by the primary operator through the foot pedal attached to the console or through the slide switch on the cryoballoon catheter. This precludes the need for the primary operator to instruct a console operator to inflate, freeze, or deflate the cryoballoon. More importantly, the Polarx™ cryoballoon catheter’s body is made of an innovative semi-elastic, thermoplastic material that eases balloon delivery and placement in different PV anatomies, possibly contributing to the shorter procedure and fluoroscopy time as well. Cryothermal energy causes vasoconstriction with a consequent reduction in blood circulation and ischemia. Simultaneously, as the catheter reaches a temperature of -40 ºC, irreversible cell damage is observed due to formation of intracellular and extracellular ice. Furthermore, with subsequent rewarming, endothelial damage occurs which leads to microthrombi formation 17. Cryoballoon temperature during freezing provides reliable information on balloon-tissue contact, highlighting the relationship between low temperatures and ablation efficiency. The study by Ciconte et al 18 and Watanabe et al 19 showed that nadir temperature reached during freezing (< -51 ºC) represents an independent predictor of absence acute PV reconnection. Furthermore, failure to reach -40 ºC in the first minute of application of cryoenergy represents an independent predictor for late reconnection. Scala et al 20 identified that PV reconnection was associated with longer time to -40 ºC and to reach this temperature in the first minute represents an independent predictor for late reconnection. Warmer temperature at 60 seconds and warmer nadir temperature was associated with PV reconnection. Chierchia et al 21 illustrated that early PV reconnection was associated with a significantly longer TTI. Similarly, Chun et al 22 showed that TTI associated with a durable PV isolation was significantly shorter than in those with electrical reconnection. A recent multicenter study has shown that thaw temperature to 0 ºC of >10 seconds significantly predicts PV isolation 23. Ghosh et al showed that predictors of PV reconnection include shorter warming time 24. In the Polarx™ group, the time to reach 0 ºC compared to the Arctic Front™ group was slower, time to reach -40 °C was faster, temperature reached at 60 seconds and the nadir temperature were lower, and thaw time to 0 °C was longer. Also, there was a significant difference in the isolation temperature between Polarx™ and Arctic Front™. In our study, the nadir temperature and thaw time to 0°C in Polarx™ met the most marked predictive criteria for successful PV isolation. Furthermore, there were no significant differences in time to isolation between Polarx™ and Arctic Front™. We could infer that these temperature differences might be due to a number of technical factors. The difference in time to reach 0°C, with Polarx™ being significantly slower than Arctic Front™, is due to the gradual increase in N2O flow over approximately 10 seconds at the start of cryoablation, enabling the cryoballoon to maintain its size and shape (and therefore occlusion) as therapy is delivered. During this period, there is cryoballoon cooling, but no significant temperature drop until the desired N2O flow is reached, after which the temperature drops quickly. We could also infer that these temperature differences might be due to different freezing kinetics of the system. Measuring temperature at probe-tissue interface or impedance drop during cryoablation may enhance assessment on the ability of both cryoballoon catheters to create lesions within the ostium for PV isolation. Despite having shorter time to reach -40 ° C in Polarx™, both groups reached -40 ° C within 60 seconds. This not only represents an acute indicator of PV isolation but also a significant predictor of permanency of PV isolation on the long term. Cumulative freeze duration was also significantly lower with Polarx™. This again might be the result of the adaptable and compliant semi-elastic, thermoplastic material the Polarx™ is made of; therefore facilitating its placement and occlusion in PV ostia despite varying PV drainage patterns. Visualization of PV electrical activity and real time PV isolation was significantly higher in the Polarx™ group than in the Arctic Front™ group. Inner-lumen mapping catheter must be positioned in a proximal portion of the PV in order to maximize the likelihood of visualizing realtime recordings without sacrificing cryoballoon stability. Once more, the very nature and design of the Polarx™ played a pivotal role in this setting. Phrenic nerve (PN) palsy is the most common complication of cryoballoon ablation 25 with an incidence of 0.37 - 1.61% 26. The course of the PN varies from each patient and it is difficult to assess each prior to the procedure. A larger RSPV diameter, a deeper balloon position outside the cardiac silhouette, and rapid temperature drops are known predictors of PN injury 27-30. In our study, there is no significant difference with the rate of PN injury between Polarx™ and Arctic Front™. All patients who had transient PN injury defined by decrease or abrupt cessation of diaphragm muscle contraction during the cryoablation had resolution of PN function after cryoablation was discontinued.
Limitations
This study compares the novel Polarx™ cryoablation system with the standard Arctic Front™ cryoablation system. This study was conducted in a small cohort of patients and was retrospective in nature. Larger studies are needed to compare the safety and efficacy of the Polarx™ cryoballoon catheter on a longer follow-up period.
Conclusions
The novel Polarx™ cryoablation system showed similar efficacy in vein occlusion and isolation and safety profile when compared to Arctic Front™ cryoablation system. Procedure time, fluoroscopy time, and cumulative freeze duration were significantly lower with Polarx™ cryoablation system.
References
- 1.Cheniti Ghassen, Vlachos Konstantinos, Pambrun Thomas, Hooks Darren, Frontera Antonio, Takigawa Masateru, Bourier Felix, Kitamura Takeshi, Lam Anna, Martin Claire, Dumas-Pommier Carole, Puyo Stephane, Pillois Xavier, Duchateau Josselin, Klotz Nicolas, Denis Arnaud, Derval Nicolas, Jais Pierre, Cochet Hubert, Hocini Meleze, Haissaguerre Michel, Sacher Frederic. Atrial Fibrillation Mechanisms and Implications for Catheter Ablation. Front Physiol. 2018;9 () doi: 10.3389/fphys.2018.01458. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Klein Gunnar, Oswald Hanno, Gardiwal Ajmal, Lüsebrink Ulrich, Lissel Christoph, Yu Hong, Drexler Helmut. Efficacy of pulmonary vein isolation by cryoballoon ablation in patients with paroxysmal atrial fibrillation. Heart Rhythm. 2008 Jun;5 (6):802–6. doi: 10.1016/j.hrthm.2008.02.014. [DOI] [PubMed] [Google Scholar]
- 3.Defaye Pascal, Kane Adama, Chaib Ali, Jacon Peggy. Efficacy and safety of pulmonary veins isolation by cryoablation for the treatment of paroxysmal and persistent atrial fibrillation. Europace. 2011 Jun;13 (6):789–95. doi: 10.1093/europace/eur036. [DOI] [PubMed] [Google Scholar]
- 4.Ciconte Giuseppe, Baltogiannis Giannis, de Asmundis Carlo, Sieira Juan, Conte Giulio, Di Giovanni Giacomo, Saitoh Yukio, Irfan Ghazala, Mugnai Giacomo, Hunuk Burak, Chierchia Gian-Battista, Brugada Pedro. Circumferential pulmonary vein isolation as index procedure for persistent atrial fibrillation: a comparison between radiofrequency catheter ablation and second-generation cryoballoon ablation. Europace. 2015 Apr;17 (4):559–65. doi: 10.1093/europace/euu350. [DOI] [PubMed] [Google Scholar]
- 5.Martins Raphaël P, Hamon David, Césari Olivier, Behaghel Albin, Behar Nathalie, Sellal Jean-Marc, Daubert Jean-Claude, Mabo Philippe, Pavin Dominique. Safety and efficacy of a second-generation cryoballoon in the ablation of paroxysmal atrial fibrillation. Heart Rhythm. 2014 Mar;11 (3):386–93. doi: 10.1016/j.hrthm.2014.01.002. [DOI] [PubMed] [Google Scholar]
- 6.Fürnkranz Alexander, Bordignon Stefano, Schmidt Boris, Gunawardene Melanie, Schulte-Hahn Britta, Urban Verena, Bode Frank, Nowak Bernd, Chun Julian K R. Improved procedural efficacy of pulmonary vein isolation using the novel second-generation cryoballoon. J Cardiovasc Electrophysiol. 2013 May;24 (5):492–7. doi: 10.1111/jce.12082. [DOI] [PubMed] [Google Scholar]
- 7.Abugattas Juan-Pablo, Iacopino Saverio, Moran Darragh, De Regibus Valentina, Takarada Ken, Mugnai Giacomo, Ströker Erwin, Coutiño-Moreno Hugo Enrique, Choudhury Rajin, Storti Cesare, De Greef Yves, Paparella Gaetano, Brugada Pedro, de Asmundis Carlo, Chierchia Gian-Battista. Efficacy and safety of the second generation cryoballoon ablation for the treatment of paroxysmal atrial fibrillation in patients over 75 years: a comparison with a younger cohort. Europace. 2017 Nov 01;19 (11):1798–1803. doi: 10.1093/europace/eux023. [DOI] [PubMed] [Google Scholar]
- 8.Knight Bradley P, Novak Paul G, Sangrigoli Robert, Champagne Jean, Dubuc Marc, Adler Stuart W, Svinarich J Thomas, Essebag Vidal, Hokanson Robert, Kueffer Fred, Jain Sandeep K, John Roy M, Mansour Moussa. Long-Term Outcomes After Ablation for Paroxysmal Atrial Fibrillation Using the Second-Generation Cryoballoon: Final Results From STOP AF Post-Approval Study. JACC Clin Electrophysiol. 2019 Mar;5 (3):306–314. doi: 10.1016/j.jacep.2018.11.006. [DOI] [PubMed] [Google Scholar]
- 9.Hermida Jean Sylvain, Chen Jian, Meyer Christian, Iacopino Saverio, Arena Giuseppe, Pavlovic Nikola, Velagic Vedran, Healey Stewart, Packer Douglas L, Pitschner Heinz-Friedrich, de Asmundis Carlo, Kuniss Malte, Chierchia Gian Battista. Cryoballoon catheter ablation versus antiarrhythmic drugs as a first-line therapy for patients with paroxysmal atrial fibrillation: Rationale and design of the international Cryo-FIRST study. Am Heart J. 2020 Apr;222 ():64–72. doi: 10.1016/j.ahj.2019.12.006. [DOI] [PubMed] [Google Scholar]
- 10.Ciconte Giuseppe, Chierchia Gian-Battista, DE Asmundis Carlo, Sieira Juan, Conte Giulio, Juliá Justo, DI Giovanni Giacomo, Wauters Kristel, Baltogiannis Giannis, Saitoh Yukio, Mugnai Giacomo, Catanzariti Domenico, Tondo Claudio, Brugada Pedro. Spontaneous and adenosine-induced pulmonary vein reconnection after cryoballoon ablation with the second-generation device. J Cardiovasc Electrophysiol. 2014 Aug;25 (8):845–851. doi: 10.1111/jce.12421. [DOI] [PubMed] [Google Scholar]
- 11.Knecht Sven, Kühne Michael, Osswald Stefan, Sticherling Christian. Quantitative assessment of a second-generation cryoballoon ablation catheter with new cooling technology-a perspective on potential implications on outcome. J Interv Card Electrophysiol. 2014 Jun;40 (1):17–21. doi: 10.1007/s10840-014-9883-1. [DOI] [PubMed] [Google Scholar]
- 12.Metzner Andreas, Reissmann Bruno, Rausch Peter, Mathew Shibu, Wohlmuth Peter, Tilz Roland, Rillig Andreas, Lemes Christine, Deiss Sebastian, Heeger Christian, Kamioka Masashi, Lin Tina, Ouyang Feifan, Kuck Karl-Heinz, Wissner Erik. One-year clinical outcome after pulmonary vein isolation using the second-generation 28-mm cryoballoon. Circ Arrhythm Electrophysiol. 2014 Apr;7 (2):288–92. doi: 10.1161/CIRCEP.114.001473. [DOI] [PubMed] [Google Scholar]
- 13.Chierchia Gian-Battista, Di Giovanni Giacomo, Ciconte Giuseppe, de Asmundis Carlo, Conte Giulio, Sieira-Moret Juan, Rodriguez-Mañero Moises, Casado Ruben, Baltogiannis Giannis, Namdar Mehdi, Saitoh Yukio, Paparella Gaetano, Mugnai Giacomo, Brugada Pedro. Second-generation cryoballoon ablation for paroxysmal atrial fibrillation: 1-year follow-up. Europace. 2014 May;16 (5):639–44. doi: 10.1093/europace/eut417. [DOI] [PubMed] [Google Scholar]
- 14.Bordignon Stefano, Fürnkranz Alexander, Dugo Daniela, Perrotta Laura, Gunawardene Melanie, Bode Frank, Klemt Anne, Nowak Bernd, Schulte-Hahn Britta, Schmidt Boris, Chun K R Julian. Improved lesion formation using the novel 28 mm cryoballoon in atrial fibrillation ablation: analysis of biomarker release. Europace. 2014 Jul;16 (7):987–93. doi: 10.1093/europace/eut400. [DOI] [PubMed] [Google Scholar]
- 15.Metzner Andreas, Rausch Peter, Lemes Christine, Reissmann Bruno, Bardyszewski Alexander, Tilz Roland, Rillig Andreas, Mathew Shibu, Deiss Sebastian, Kamioka Masashi, Toennis Tobias, Lin Tina, Ouyang Feifan, Kuck Karl-Heinz, Wissner Erik. The incidence of phrenic nerve injury during pulmonary vein isolation using the second-generation 28 mm cryoballoon. J Cardiovasc Electrophysiol. 2014 May;25 (5):466–470. doi: 10.1111/jce.12358. [DOI] [PubMed] [Google Scholar]
- 16.Aryana Arash, Morkoch Shemsa, Bailey Sean, Lim Hae W, Sara Rahmani, d'Avila André, O'Neill P Gearoid. Acute procedural and cryoballoon characteristics from cryoablation of atrial fibrillation using the first- and second-generation cryoballoon: a retrospective comparative study with follow-up outcomes. J Interv Card Electrophysiol. 2014 Nov;41 (2):177–86. doi: 10.1007/s10840-014-9942-7. [DOI] [PubMed] [Google Scholar]
- 17.Osório Thiago Guimarães, Coutiño Hugo-Enrique, Brugada Pedro, Chierchia Gian-Battista, De Asmundis Carlo. Recent advances in cryoballoon ablation for atrial fibrillation. Expert Rev Med Devices. 2019 Sep;16 (9):799–808. doi: 10.1080/17434440.2019.1653181. [DOI] [PubMed] [Google Scholar]
- 18.Ciconte Giuseppe, Mugnai Giacomo, Sieira Juan, Velagić Vedran, Saitoh Yukio, Irfan Ghazala, Hunuk Burak, Ströker Erwin, Conte Giulio, Di Giovanni Giacomo, Baltogiannis Giannis, Wauters Kristel, Brugada Pedro, de Asmundis Carlo, Chierchia Gian-Battista. On the Quest for the Best Freeze: Predictors of Late Pulmonary Vein Reconnections After Second-Generation Cryoballoon Ablation. Circ Arrhythm Electrophysiol. 2015 Dec;8 (6):1359–65. doi: 10.1161/CIRCEP.115.002966. [DOI] [PubMed] [Google Scholar]
- 19.Watanabe Ryuta, Okumura Yasuo, Nagashima Koichi, Iso Kazuki, Takahashi Keiko, Arai Masaru, Wakamatsu Yuji, Kurokawa Sayaka, Ohkubo Kimie, Nakai Toshiko, Yoda Shunichi, Watanabe Ichiro, Hirayama Atsushi, Sonoda Kazumasa, Tosaka Toshimasa. Influence of balloon temperature and time to pulmonary vein isolation on acute pulmonary vein reconnection and clinical outcomes after cryoballoon ablation of atrial fibrillation. J Arrhythm. 2018 Oct;34 (5):511–519. doi: 10.1002/joa3.12108. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Scala Oriana, Borio Gianluca, Paparella Gaetano, Varnavas Varnavas, Ströker Erwin, Guimaraes Osorio Thiago, Terasawa Muryo, Sieira Juan, Maj Riccardo, Rizzo Alessandro, Al-Hosari Maysam M, Galli Alessio, Brugada Pedro, de Asmundis Carlo, Chierchia Gian-Battista. Predictors of durable electrical isolation in the setting of second-generation cryoballoon ablation: A comparison between left superior, left inferior, right superior, and right inferior pulmonary veins. J Cardiovasc Electrophysiol. 2020 Jan;31 (1):128–136. doi: 10.1111/jce.14286. [DOI] [PubMed] [Google Scholar]
- 21.Chierchia Gian-Battista, de Asmundis Carlo, Namdar Mehdi, Westra Sjoerd, Kuniss Malte, Sarkozy Andrea, Bayrak Fatih, Ricciardi Danilo, Casado-Arroyo Ruben, Rodriguez Manero Moises, Rao Jayakeerthi Y, Smeets Joep, Brugada Pedro. Pulmonary vein isolation during cryoballoon ablation using the novel Achieve inner lumen mapping catheter: a feasibility study. Europace. 2012 Jul;14 (7):962–7. doi: 10.1093/europace/eus041. [DOI] [PubMed] [Google Scholar]
- 22.Chun Kr Julian, Bordignon Stefano, Gunawardene Melanie, Urban Verena, Kulikoglu Mehmet, Schulte-Hahn Britta, Nowak Bernd, Schmidt Boris. Single transseptal big Cryoballoon pulmonary vein isolation using an inner lumen mapping catheter. Pacing Clin Electrophysiol. 2012 Nov;35 (11):1304–11. doi: 10.1111/j.1540-8159.2012.03475.x. [DOI] [PubMed] [Google Scholar]
- 23.Aryana Arash, Mugnai Giacomo, Singh Sheldon M, Pujara Deep K, de Asmundis Carlo, Singh Steve K, Bowers Mark R, Brugada Pedro, d'Avila André, O'Neill Padraig Gearoid, Chierchia Gian-Battista. Procedural and biophysical indicators of durable pulmonary vein isolation during cryoballoon ablation of atrial fibrillation. Heart Rhythm. 2016 Feb;13 (2):424–32. doi: 10.1016/j.hrthm.2015.10.033. [DOI] [PubMed] [Google Scholar]
- 24.Ghosh Justin, Martin Andrew, Keech Anthony C, Chan Kim H, Gomes Sean, Singarayar Suresh, McGuire Mark A. Balloon warming time is the strongest predictor of late pulmonary vein electrical reconnection following cryoballoon ablation for atrial fibrillation. Heart Rhythm. 2013 Sep;10 (9):1311–7. doi: 10.1016/j.hrthm.2013.06.014. [DOI] [PubMed] [Google Scholar]
- 25.Andrade Jason G, Khairy Paul, Guerra Peter G, Deyell Marc W, Rivard Lena, Macle Laurent, Thibault Bernard, Talajic Mario, Roy Denis, Dubuc Marc. Efficacy and safety of cryoballoon ablation for atrial fibrillation: a systematic review of published studies. Heart Rhythm. 2011 Sep;8 (9):1444–51. doi: 10.1016/j.hrthm.2011.03.050. [DOI] [PubMed] [Google Scholar]
- 26.Sacher Frederic, Jais Pierre, Stephenson Kent, O'Neill Mark D, Hocini Meleze, Clementy Jacques, Stevenson William G, Haissaguerre Michel. Phrenic nerve injury after catheter ablation of atrial fibrillation. Indian Pacing Electrophysiol J. 2007 Jan 01;7 (1):1–6. [PMC free article] [PubMed] [Google Scholar]
- 27.Miyazaki Shinsuke, Kajiyama Takatsugu, Watanabe Tomonori, Hada Masahiro, Yamao Kazuya, Kusa Shigeki, Igarashi Miyako, Nakamura Hiroaki, Hachiya Hitoshi, Tada Hiroshi, Hirao Kenzo, Iesaka Yoshito. Characteristics of Phrenic Nerve Injury During Pulmonary Vein Isolation Using a 28-mm Second-Generation Cryoballoon and Short Freeze Strategy. J Am Heart Assoc. 2018 Mar 24;7 (7) doi: 10.1161/JAHA.117.008249. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28.Saitoh Yukio, Ströker Erwin, Irfan Ghazala, Mugnai Giacomo, Ciconte Giuseppe, Hünük Burak, Velagić Vedran, Overeinder Ingrid, Tanaka Kaoru, Brugada Pedro, de Asmundis Carlo, Chierchia Gian-Battista. Fluoroscopic position of the second-generation cryoballoon during ablation in the right superior pulmonary vein as a predictor of phrenic nerve injury. Europace. 2016 Aug;18 (8):1179–86. doi: 10.1093/europace/euv362. [DOI] [PubMed] [Google Scholar]
- 29.Abugattas Juan-Pablo, de Asmundis Carlo, Iacopino Saverio, Salghetti Francesca, Takarada Ken, Coutiño Hugo-Enrique, Ströker Erwin, De Regibus Valentina, de Greef Yves, Brugada Pedro, Sieira Juan, Chierchia Gian-Battista. Phrenic nerve injury during right inferior pulmonary vein ablation with the second-generation cryoballoon: clinical, procedural, and anatomical characteristics. Europace. 2018 Oct 01;20 (10):e156–e163. doi: 10.1093/europace/eux337. [DOI] [PubMed] [Google Scholar]
- 30.Mugnai Giacomo, de Asmundis Carlo, Velagic Vedran, Hünük Burak, Ströker Erwin, Wauters Kristel, Irfan Ghazala, Overeinder Ingrid, Hacioglu Ebru, Hernandez-Ojeda Jaime, Poelaert Jan, Verborgh Christian, Paparella Gaetano, Brugada Pedro, Chierchia Gian-Battista. Phrenic nerve injury during ablation with the second-generation cryoballoon: analysis of the temperature drop behaviour in a large cohort of patients. Europace. 2016 May;18 (5):702–9. doi: 10.1093/europace/euv346. [DOI] [PubMed] [Google Scholar]