Novel ablation technique shows promise
SHANGHAI, CHINA. Prof. Haissaguerre and colleagues in Bordeaux, France discovered in 1998 that paroxysmal atrial fibrillation (PAF) was triggered by ectopic activity in the pulmonary veins. Since then catheter ablation aimed at isolating the pulmonary veins from the left atrium has been the preferred non-drug approach for dealing with PAF. Pulmonary vein isolation (PVI) may be performed using electrophysiological mapping (using a multipolar Lasso catheter) or anatomical mapping (CARTO) to establish the exact location of the pulmonary veins.

More recently procedures have emerged that target the atrium walls (substrate) where the aberrant impulses from the pulmonary veins (PVs) organize themselves to initiate and sustain atrial fibrillation. Chief among these are the strategy targeting complex fractionated atrial electrograms developed by Dr. Koonlawee Nademanee and the FIRM procedure targeting electric rotors and focal impulses developed by Dr. Sanjiv M. Narayan.

A group of researchers from the Second Military Medical University in Shanghai now reports preliminary results of a new ablation procedure which, rather than encircling the pulmonary veins, creates three short radial lines of lesion emanating from each pulmonary vein and extending into the left atrium (to the point where no PV potentials are present).

The clinical trial of the new procedure involved 86 patients with PAF who were randomized to receive the new pulmonary antrum radial-linear (PAR) ablation procedure (42 patients) or a standard PVI procedure (44 patients) at one of 4 ablation centers in Shanghai. The average total procedure time in the PAR group was 161 minutes vs. 199 minutes in the PVI group. Fluoroscopy time was 25 and 32 minutes respectively. NOTE: PVI was not performed in the PAR patients and none of them demonstrated complete isolation of the PVs. The average age of the patients was 64 years and 63% were men. None of the patients had heart disease, but 45% had hypertension and 17% had diabetes. Left atrium diameter varied from 43 mm to 49 mm (those having a left atrium diameter greater than 50 mm were excluded from the trial) and average left ventricular ejection fraction was 71%.

Follow-up included electrocardiograms, 3-day event recording every 3 months, and 24-hour Holter monitoring 6 months after the procedure and at the final follow-up visit. At 14 months following a single ablation procedure, 74% of the patients in the PAR group were free of atrial fibrillation, atrial flutter, and atrial tachycardia (no episodes lasting longer than 30 seconds) without the use of antiarrhythmic drugs (86% AF-free with the use of drugs). Corresponding percentages for patients in the PVI group were 50% and 59%. No major adverse events were observed during the trial. The researchers noted a significant post-procedural decrease in left atrium diameter in the PAR group. They conclude that the PAR procedure is simple, safe and effective in patients with paroxysmal AF and warrants further large scale trials.
Zhao, X, et al. Pulmonary antrum radial-linear ablation for paroxysmal atrial fibrillation. Circulation Arrhythmia and Electrophysiology, Vol. 6, April 2013, pp. 310-17
Calkins, H. Has the time come to abandon the concept that "pulmonary vein isolation is the cornerstone of atrial fibrillation ablation"? Circulation Arrhythmia and Electrophysiology, Vol. 6, April 2013, pp. 241-42