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Abstract Atrial fibrillation (AF) is the most common sustained cardiac rhythm disturbance, increasing in prevalence with age. Pulmonary vein isolation (PVI) has become the mainstream therapy for patients with drug-refractory paroxysmal AF, since PV foci were discovered as the trigger for its initiation and perpetuation. The efficacy and safety of catheter ablation of paroxysmal AF have been reported by several randomized studies. Although focal RF catheters have been the standard of care for AF ablation, balloon-based technologies were developed to deliver ablative energy in a more continuous pattern without conduction gaps during cardiac tissue isolation. Since the release of the first-generation cryoballoon, data from both single-centre studies and multicentre registries have demonstrated acute PVI and freedom from AF at rates comparable to those of RF. Aim of the study: This study aims to compare between cryoballoon ablation and radiofrequency catheter ablation of the pulmonary veins in patients with paroxysmal atrial fibrillation in terms of safety, efficacy and long term follow up. Methods: The study cohort consisted of 113 patients who underwent catheter ablation for paroxysmal atrial fibrillation (PAF) by either radiofrequency (RF) or cryoballoon (CB). Forty-four consecutive patients (CB, n=20, RF, n=24) were operated at Ain Shams University hospitals, Cairo, Egypt, and a matched group of 69 patients (CB, n=24, RF, n=45) having their procedures at Royal Brompton and Harefield NHS foundation trust, London, UK. Symptomatic patients with failed medical treatment with at least one of class I or III antiarrhythmic drugs (AADs) and AF documented by 12-lead ECG were included. Full history, examination and preoperative investigations were performed. AF ablation as PVI was implemented either by second generation cryoballoon or radiofrequency catheter ablation. Patient follow up was arranged after a 3-month blanking period at 3, 6 and 12 months after the procedure to detect success rate by history taking, surface ECG and ambulatory ECG monitoring. Results: The baseline patient characteristics were similar between CB and RF groups where mean age in years was 53.84 vs 55.78, female patients were 40.9% vs 34.8%, BMI was 28.72 vs 28.08 kg/m2, diabetic patients were 6.8% vs 7.2%, and hypertensives 34.1% vs 30.4% respectively. Other comorbid conditions, and the median CHA2DS2VASc. There was a significant difference between the two groups in the documented duration of AF symptoms which was less in CB group [9 vs 24, p<0.0001]. Regarding echocardiographic parameters, a difference was observed between both groups where CB patients had significantly smaller LA (37.64 vs 40.42, p=0.008) while the mean EF was similar (63.68 vs 61.99, p=0.15) and most of the study population had mild or no mitral regurgitation. All the four classes of antiarrhythmic drugs were used, with at least one drug, to alleviate symptoms before planned procedures in both groups. In most patients (95.5% for CB, 82.6% for RF, p=0.07), the usual anatomical arrangement was found with four pulmonary veins, two on each side (95.5% for CB, 82.6% for RF, p=0.07), with lesser incidence of a common left trunk and a right middle pulmonary vein (RMPV). In both groups, PVI was attained by bilateral circumferential ablation surrounding ipsilateral pulmonary veins, and acute success was confirmed by both exit and entrance block. Neither additional lesions were delivered out of the veins, nor cavo-tricuspid isthmus (CTI) ablation line. The mean procedural times in minutes were significantly less in the CB group (94.37 vs 184.57, p<0.0001), while the median fluoroscopy times were similar [30 (11.04 - 40) vs 37.25 (14.2 - 70), p=0.172]. The length of peri-procedural hospital stay, in days, was significantly less in the CB group (1.59 ± 0.50 vs 2.13 ± 1.08, p=0.003). The incidence of pericardial effusion with tamponade was documented in 1 patient (2.3%) in the CB and 1(1.4%) in the RF group in addition to a minor effusion in 1(1.4%). Long term phrenic nerve paresis occurred only in CB group in 1(2.3%) patient during freezing of the RSPV, despite continuous monitoring of diaphragmatic contractions. There were no cases of mortality, and no significant oesophageal thermal lesions, groin complications, nor complications related to general anaesthesia were reported. An ECG or an ambulatory monitor was used to confirm AF recurrence. The incidence of AF symptoms and documented AF recurrence between CB and RF groups were similar during the first 90 day-blanking period after the procedure (18.2% vs 23.2%, p=0.526), at 6 months (20.5% vs 24.6%, p=0.606), and at 12 months (27.3% vs 30.4%, p=0.719). The scheduling of redo procedures was also comparable (6.8% vs. 17.4%; p=0.106). After an initial 90-day blanking period, the Kaplan Meier estimates of arrhythmia-free survival for a period of 1 year were comparable between both groups (log rank test, p=0.606). Among the patients undergoing RF ablation procedure, 32(46%) were operated by the conventional RF ablation catheter compared to 37(54%) by the contact-force catheter. The force-sensing catheter was used in older patients (62.38 vs. 48.16, p<0.001), females (18 (48.6%) vs. 6 (18.8%), p<0.001) with higher mean CHA2DS2VASc score [0 (0 - 1) vs. 2 (0 - 3); p=0.010], history of ischaemia (0 vs. 3(8.1%); p=0.10), and with longer AF duration [42 (24 - 86) vs.16 (10 - 40); p=0.003], and the above values were significant. BMI and associated comorbidities, like Diabetes, hypertension, and previous thromboembolic events, were similar between the two groups. The procedural time was significantly less in the contactforce group (235.22 vs. 140.76; p<0.0001) compared to the conventional group, so was the fluoroscopy time [74 (56 - 95) vs. 15.09 (11.6 - 23.42); p<0.0001]. The arrhythmia-free survival over 1 year was represented by Kaplan-Meier curves between both groups showed similar outcomes with a trend to less recurrences in the contact-force group (log rank test, p=0.612). On looking at patient characteristics and procedural data of patients with or without recurrences, no significant differences were observed in age, gender, AF duration, LA anteroposterior diameter, LV ejection fraction and associated comorbidities like hypertension. However, in comparison to the no-recurrence group, the recurrence group showed more occurrences of AF during blanking (54.5% vs 7.5%; p<0.0001), a longer hospital stay (2.31 vs 1.77; p=0.006), presence of Diabetes Mellitus (15.2% vs. 3.8%; p=0.032), and a higher BMI (29.69 vs. 27.77;p=0.044) |