More ischaemic lesions with PVAC than with other techniques

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The incidence of silent cerebral lesions after pulmonary vein isolation is different depending on the technology used, a new study has shown. Atrial fibrillation patients treated with multi-electrode PVAC showed higher incidence of silent cerebral ischaemic events compared to irrigated radiofrequency and cryoballoon ablation.

The paper “AF Ablation Technologies and Silent Cerebral Ischemic Lesions” was published in the 31 March 2011 issue of Journal of Cardiovascular Electrophysiology.

“Silent cerebral ischaemic lesions have recently emerged as the most frequent complications after pulmonary vein isolation. To reduce thromboembolic complications, new types of catheters and energy source have been introduced in clinical practice,” the authors, led by Fiorenzo Gaita and Alessandro Blandino, Cardiology Division, Department of Internal Medicine, San Giovanni Battista Hospital, University of Turin, Italy, wrote.

Symptomatic thromboembolic events following an ablation procedure by non-irrigated radiofrequency catheters have been described in up to 1.8–2%, reduced to 0.3–0.7% by irrigated catheters.

However, recent evidence has demonstrated that symptomatic thromboembolic events (stroke or transient ischaemic attack) are only the tip of the possible thromboembolic sequelae of a catheter ablation, strongly represented by silent cerebral lesions.

With the use of pre- and postablation cerebral magnetic resonance imaging (MRI), it has been shown that despite the use of an open irrigated radiofrequency catheter, the most frequently applied type of catheter and energy source, AF ablation procedure may cause silent ischaemic lesions in up to 11–14% of the cases; and this incidence may be influenced by factors as cardioversion and activated clotting time (ACT) values.

“Recently, an alternative form of energy (cryoenergy), already used in different ablation contexts, and a new catheter (multielectrode nonirrigated catheter, PVAC, associated with duty-cycled RF generator) have been developed with the double aim of facilitating AF ablation and reducing complications,” the authors wrote. “The purpose was to compare the incidence of new silent cerebral ischaemic events in patients with paroxysmal atrial fibrillation undergoing pulmonary vein isolation with different ablation technologies.”

Between January and August 2010, 108 consecutive patients (67% men; age 56 ± 9 years) with a history of paroxysmal AF and refractory to antiarrhythmic drugs underwent pulmonary vein isolation in four centres in Italy, France and Germany. Patients underwent pulmonary vein isolation performed with irrigated radiofrequency catheter (n=36) using the Navistar Thermocool (Biosense Webster), multielectrode catheter (PVAC, Ablation Frontiers/Medtronic) associated with duty-cycled radiofrequency generator (n=36) and cryoballoon (n=36) with the Arctic Front balloon (Cryocath/Medtronic).

Exclusion criteria were age <20 and >80 years, severe valvular heart disease, acute coronary syndrome three months before procedure, previous catheter ablation, previous transient ischaemic attack or stroke, previous pacemaker or implantable cardioverter-defibrillator implant, or any contraindication to perform cerebral MRI.

The protocol included a cerebral magnetic resonance imaging before and after the procedure. After pulmonary vein isolation, the following patients showed new silent cerebral ischaemic lesions at postprocedural cerebral magnetic resonance imaging: three patients in irrigated radiofrequency catheter group (8.3%), 14 patients in the PVAC group (38.9%), and two patients in the cryoablation group (5.6%).

PVAC related to significant higher incidence of silent cerebral ischaemic events compared to irrigated radiofrequency (p=0.002) and cryoballoon (p=0.001), whereas no statistical differences were found between the irrigated radiofrequency catheter and cryoballoon groups (8.3% vs. 5.6%, p=0.5). At the multivariate analysis, the only independent predictor of new ischaemic asymptomatic cerebral lesions after pulmonary vein isolation was ablation performed with PVAC (OR 1.48 95% CI 1.19–1.62, p<0.001).

PVAC increases the risk of 1.48 times compared to irrigated radiofrequency and cryoballoon ablation. 

“Whichever catheter and energy source is used, a risk of postablation new silent cerebral thromboembolic events is always present,” the authors wrote. “The use of PVAC increases the risk of new silent cerebral ischaemic events of 48% compared to irrigated radiofrequency and cryoballoon ablation. When AF ablation is approached, in addition to the well-described ablation complications, physicians must be aware of the not negligible silent thromboembolic risk and must inform the patients that risk may depend on the ablation technology applied,” they concluded.

Medtronic released a statement after the publication of the study:

  • Acute silent cerebral embolism is not a new phenomenon, and rates from 14% to 47% have been previously reported in the literature for AF ablation and selected invasive cardiac procedures. While the study demonstrated a rate of 38.9%, a positive post-procedural DW-MRI was not reported to be associated with clinical events.
  • Medtronic supports the trials currently underway to identify patients who can benefit most from therapies such as Phased RF, including an active research and engineering teams focused on investigating and understanding acute silent cerebral embolism associated with AF ablation. We have actively engaged clinical research scientists, independent AF ablation experts, and physicians who specialise in neurology and neuro-radiology to gain additional perspective and input on this observation.
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