Summary
Background
Systematic use of a 28 mm balloon has been proposed for pulmonary vein cryoisolation in patients with atrial fibrillation.
Objective
To assess the results of a dual balloon size strategy using a 23 or 28 mm cryoballoon catheter for pulmonary vein isolation.
Methods
A total of 118 patients (mean age 56 ± 10 years) with paroxysmal ( n = 85) or persistent atrial fibrillation ( n = 33) were enrolled. Patients with four pulmonary veins < 20 mm in diameter were isolated with a 23 mm cryoballoon ( n = 29); patients with one pulmonary vein diameter ≥ 20 mm were isolated with a 28 mm cryoballoon ( n = 89).
Results
No significant difference in procedural variables was observed between the two groups. AF-free survival, after a mean follow-up of 19.9 ± 5 months, was similar in the two groups (69% vs 62%; p = 0.57 and between patients with paroxysmal atrial fibrillation (68% vs 68%; p = 0.91) or persistent AF (75% vs 48%; p = 0.60). AF duration before the ablation procedure ( p = 0.005) was an independent predictor of AF recurrence. Phrenic nerve palsy rate was not statistically different in the two groups (4 [14%] vs 9 [10%]; p = 0.73). The temperature in the right superior pulmonary vein ( p = 0.008) was an independent predictor of phrenic nerve palsy. Five patients developed left atrial flutter with the 28 mm diameter balloon versus none with the 23 mm balloon.
Conclusions
A dual balloon size strategy was not associated with a lower AF-free survival or a higher procedure-related complication rate in patients in whom the 23 mm balloon was used. Pulmonary vein isolation with a 23 mm cryoballoon catheter appears to be an appropriate option in selected patients with small pulmonary vein diameters.
Résumé
Background
L’utilisation systématique d’un ballon de 28 mm a été proposée pour la cryo-isolation des veines pulmonaires (VP) chez les patients ayant une fibrillation atriale (FA).
Objectif
Évaluer une stratégie utilisant deux tailles de ballon (23 ou 28 mm) pour l’isolation des VP.
Méthode
Cent dix-huit patients (âge moyen 56 ± 10 ans) ayant une FA paroxystique ( n = 85) ou une FA persistante ( n = 33) ont été inclus. Les patients dont le diamètre des quatre VP est inférieur à 20 mm ont été isolé avec un ballon de 23 mm ( n = 29), et ceux dont le diamètre d’une des VP est supérieure ou égale à 20 mm avec un ballon de 28 mm ( n = 89).
Résultats
Les paramètres procéduraux sont similaires dans les deux groupes. À 19,9 ± 5 mois, le maintien du rythme sinusal est comparable dans les deux groupes (69 % versus 62 % ; p = 0,57), chez les patients ayant une FA paroxystique (68 % versus 68 % ; p = 0,91) et une FA persistante (75 % versus 48 % ; p = 0,60). La durée de la FA avant l’ablation ( p = 0,005) est identifié comme facteur prédictif indépendant de la récidive. La paralysie du nerf phrénique est comparable dans les deux groupes (quatre [14 %] versus neuf [10 %] ; p = 0,73). La température dans la VP supérieure droite ( p = 0,008) est un facteur prédictif indépendant de la paralysie du nerf phrénique. Cinq patients développent un flutter atrial dans le groupe traité avec un ballon de 28 mm et aucun dans le groupe traité avec un ballon de 23 mm.
Conclusion
Dans la stratégie utilisant deux tailles de ballons pour la cryo-isolation des VP, le ballon de 23 mm n’est pas associé à mauvais résultat ni à un taux de complication élevé. L’utilisation du ballon de 23 mm paraît être une alternative appropriée pour des patients sélectionnés ayant de petites VP.
Introduction
PV isolation with radiofrequency is an established treatment option for patients with AF. Use of radiofrequency cures AF episodes in 50–70% of patients . Cryoablation is an alternative strategy developed to overcome some of the disadvantages of radiofrequency . Recently, a double-lumen cryoballoon catheter (Arctic Front, Cryocath Technologies, Montreal, Canada) was used for circumferential PV isolation. This catheter is available in two sizes: 23 and 28 mm diameter. Previous clinical studies have demonstrated that cryoablation is a safe and effective method for PV isolation . The major reported complication of a cryoballoon catheter is right phrenic nerve palsy . In one study, this complication was observed mainly with the 23 mm cryoballoon catheter . Other authors have suggested that systematic use of a 28 mm cryoballoon catheter may reduce the incidence of phrenic nerve palsy .
The objective of this study was to assess the results of a dual balloon size strategy with a 23 or a 28 mm cryoballoon catheter for PV isolation and to compare the results according to balloon size.
Methods
Patients
A total of 118 consecutive patients were enrolled prospectively between July 2006 and September 2009, for PV cryoballoon isolation for symptomatic AF. All patients provided written informed consent. Inclusion criteria were: history of highly symptomatic paroxysmal or persistent AF despite treatment with at least one antiarrhythmic drug. Exclusion criteria were the presence of left atrial thrombus and a left atrial surface area > 35 cm 2 . Of the 118 patients, 29 underwent PV isolation with a 23 mm cryoballoon and 89 were treated with a 28 mm cryoballoon.
Preablation
Before ablation, all patients attended a clinical visit with review of medical records including electrocardiograms and Holter electrocardiogram documenting AF. The medical history was obtained and the risks of ablation were discussed in detail with the patient. All patients had received effective anticoagulation for ≥ 1 month, with a weekly assessed international normalized ratio > 2. Oral anticoagulation was stopped 4 days before the procedure and replaced by a daily curative dose of fractionated heparin.
Ablation procedure
Before the procedure, detailed information on left atrial anatomy was obtained by computed tomography and PV diameters were measured in order to select the more appropriate cryoballoon (Arctic Front, Cryocath) size. Two balloon catheter sizes are available (23 mm and 28 mm diameters). A 23 mm cryoballoon catheter was preferred when the maximum diameter of all four PVs was < 20 mm and a 28 mm was used when the diameter of one of the PVs was ≥ 20 mm. All procedures were performed with the patient under deep sedation.
A 6F decapolar catheter was placed in the coronary sinus via the right jugular vein, and a 6F quadripolar catheter was placed in the His bundle region via the right femoral vein. A single transseptal puncture was performed under fluoroscopic guidance via a right femoral vein approach. A 70–100 IU/kg intravenous heparin bolus was given and a continuous infusion was administered to maintain the activated clotting time > 300 s. The transseptal sheath was exchanged for the 12 F transseptal sheath (FlexCath, Montreal, Canada) in order to introduce the cryoballoon catheter into the left atrium. Before PV isolation, a circular mapping catheter (Lasso, Biosense Webster Inc., Diamond Bar, CA, USA) was advanced into each PV ostium to obtain the baseline electrical pattern. The transseptal sheath was flushed constantly with heparinized saline. After withdrawing the mapping catheter, a 23 or 28 mm cryoballoon was advanced over the wire in the left atrium, inflated and positioned at the ostium of each PV. Vessel occlusion was assessed by a selective contrast injection and graded on a semiquantitative scale from 1 to 4. An occlusion was considered to be grade 4 when selective contrast injection showed total contrast retention with no backflow into the atrium, grade 3 when contrast injection showed minimal backflow into the atrium, grade 2 when contrast injection showed mild backflow into the atrium and grade 1 when contrast injection showed immediate rapid outflow from the PV. Cryoenergy was given for 240 s per application and consisted of a minimum of two applications for each vein. During the freezing cycle, local temperature from a sensor at the proximal part of the cryoballoon, and oesophageal temperature from an oesophageal probe were monitored continuously. Before right superior PV ablation, a quadripolar catheter was positioned in the superior vena cava for continuous phrenic nerve stimulation during cryoablation. The application was terminated on loss of stimulation. After targeting all PVs, the cryocatheter was exchanged for the mapping catheter to check for any remaining electrical activity. PV isolation was considered to be complete when the loss of all PV potentials was recorded, and partial when residual PV potentials were recorded. If the recording showed partial isolation, the cryoballoon was repositioned.
Follow-up
After ablation, patients were treated with intravenous heparin. Oral anticoagulation was started on the day after the procedure. All patients were reviewed in the outpatient clinic after 3 months. Follow-up included physical examination, telephone contact, electrocardiographic and Holter monitoring at 3 months and 6 months. In December 2009 recent data (Holter and medical records < 2 months) or telephone contact were obtained for all patients. AF recurrence was defined as documented AF episodes lasting > 30 s.
Statistical analysis
Statistical analysis was performed with SPSS 11.0 (SPSS Inc., Chicago, Illinois, USA). Quantitative variables were expressed as mean ± standard deviation and were compared with Student’s t -test. Categorical variables were expressed as percentages and were compared with the Chi 2 test. The cumulative probability of AF-free survival was estimated by the Kaplan–Meier actuarial methods, at 1-month intervals. The log rank test was used to determine any significant difference. A multivariate logistic regression model was used to identify factors predictive of phrenic nerve palsy. Multivariate Cox regression models were used to identify factors predictive of AF-free survival and were systematically adjusted for age and sex. A probability of p < 0.05 was considered statistically significant.
Results
A total of 118 patients (91 men) with a mean age of 56 ± 10 years were included in the study. Indications for PV isolation were symptomatic paroxysmal AF in 85 (72%) patients and persistent AF in 33 (28%) patients. The mean procedure time was 185 min, the mean cryoenergy time was 39 min and the mean fluoroscopy exposure was 509 mGy.
Clinical and procedural characteristics
Tables 1 and 2 , respectively, show the clinical and procedural characteristics for the two groups. Body mass index ( p = 0.04) and left atrial surface area ( p < 0.001) were significantly lower in the 23 mm balloon group. The ratio between PV and balloon sizes was lower in the 28 mm balloon group ( p < 0.001). Procedural characteristics were similar in both groups. When detailed variables of each PV isolation were compared ( Table 2 ), a higher occlusion grade was observed for the left inferior PV ( p = 0.004), right superior PV (RSPV) ( p = 0.03) and right inferior PV ( p = 0.001) in the 23 mm balloon group. A lower cryoenergy temperature of all PVs was significantly associated with PV isolation using a 23 mm balloon.
| Parameters | 23 mm balloon ( n = 29) | 28 mm balloon ( n = 89) | p |
|---|---|---|---|
| Age (years) | 54 ± 13 | 57 ± 9 | 0.15 |
| Men/women ( n ) | 15/14 | 76/13 | < 0.001 |
| Body mass index (kg/m 2 ) | 26 ± 5 | 29 ± 8 | 0.04 |
| High blood pressure, n (%) | 11 (39) | 42 (48) | 0.43 |
| Other heart disease, n (%) | 6 (21) | 21 (18) | 0.27 |
| AF duration (years) | 3.9 ± 4.2 | 3.9 ± 4.0 | 0.99 |
| Paroxysmal AF, n (%) | 25 (86) | 60 (67) | 0.05 |
| Persistent AF, n (%) | 4 (14) | 29 (32) | 0.06 |
| Left atrial surface area (cm 2 ) | 20 ± 4 | 25 ± 6 | < 0.001 |
| Maximal PV diameter (mm) | 19 ± 2 | 20 ± 2 | < 0.001 |
| PV diameter/balloon diameter (mm) | 0.81 | 0.72 | < 0.001 |
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