Randomized Trial of Two Different Strategies to Treat Paroxysmal Atrial Fibrillation

Atrial fibrillation can be cured by elimination of triggering events such as atrial extrasystoles originating from the pulmonary veins (PV) by selective or linear radiofrequency current applications.

Although electrical isolation can be demonstrated by a circumferential mapping catheter positioned at the PV ostium, longterm effect of such EP-guided PV isolation procedures achieve about 60-70% of stable sinus rhythm during follow-up even in experienced centers. Re-investigation of symptomatic patients after initially electrically isolated PVs demonstrated a substantial amount of PV reconduction which might explain the arrhythmia recurrence.

Although it was demonstrated that linear lesions for PV isolation is superior to the selective ablation approach, conflicting data exists on the necessity to achieve complete linear lesions. The groups of Pappone et al and Oral et al both published a success rate of more than 90% of patients in sinusrhythm irrespective of the line completeness, which both groups estimated to be reached in only 30% of cases.

Several advantages and disadvantages could advocate for either the complete versus the incomplete ablation strategy: Performing the complete EP-guided linear PV isolation strategy might take longer (mean duration 4.5 hours vs about 2 hours) and could thereby potentially result in a higher risk of procedure-associated complications (air embolism, thrombus formation, perforation). In addition, three transseptal sheaths might increase the risk of tamponade and might aggravate the ability to safely navigate catheters in the left atrium. Certainly, the procedure costs are higher, since in addition to the 3D mapping system two circular mapping catheters are mandatory to facilitate the lesion deployment and avoidance of intra-PV ablation.

In addition, an ablation strategy that does not depend on complete line deployment may be sufficient to achieve stable sinus rhythm. Although, additional linear lesions between the PV isolation segments and towards the mitral annulus as proposed by several centers with incomplete linear PV isolation approaches might not be necessary to achieve stable sinus rhythm. Potential complications such as atrio-esophageal fistula formation could be avoided if no additional lesions eg. along the LA roof would be necessary. Both the costs of the additional material (transseptal sheaths, circular mapping catheters) and the shorter procedure duration (about 2 hours) would be reduced. On the other hand, these costs would be balanced by the reduced number of re-ablation, if incomplete PV isolation would indeed lead to a higher AF recurrence rate.

Since no data exist on the time course of the deployed ablation lines. Do patients with recurrences of AF always have PV reconduction ? Vice versa, it also remains unclear if all patients with stable sinus rhythm do experience this effect based on longterm PV isolation. To assess the significance of the time course of PV isolation, the proposed study protocol consists therefore of an invasive re-evaluation of all primarily ablated pts scheduled after 3 months of follow-up regardless of arrhythmia recurrence to investigate PV conduction properties.

Finally, patients with symptomatic AF who underwent intensified ECG monitoring indicate that the standard clinical procedures (assessment of symptoms and surface ECG recordings at long intervals) are not sufficient to detect recurrent AF. Therefore, daily ECG monitoring is planned in this trial to detect asymptomatic episodes of AF.

The proposed study protocol aims to investigate in prospective, randomized fashion the significance of complete versus incomplete PV isolation by RFC-induced linear lesions. The ablation will be randomized to a linear encircling around the ipsilateral PVs with the endpoint of complete PV isolation proven by two circumferential mapping catheters versus the same ablation procedure which will be terminated instantaneously when total PV isolation occurs, thereby allowing at least one conduction gap along the isolation line. An invasive re-evaluation is scheduled after 3 months for all pts to assess longterm PV conduction properties.