الفهرس 
ATRIAL FIBRILLATION AND CATHETER-BASED TREATMENTOnly 14 pages are availabe for public view
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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)