Comparison Between Contact Force Monitoring and Unipolar Signal Modification as a Guide for Catheter Ablation of Atrial Fibrillation

Abstract

Background: Both contact force monitoring (CFM) and unipolar signal modification (USM) are guides for ablation, which improve the efficacy of pulmonary vein isolation of atrial fibrillation. We sought to compare the outcomes of atrial fibrillation ablation guided by CFM or USM. Methods: A total of 136 patients with paroxysmal atrial fibrillation underwent a circumferential pulmonary vein isolation using CF sensing ablation catheters and were randomly assigned to undergo catheter ablation guided by either CFM (CFM-guided group: n=70) or USM (USM-guided group: n=66). In the USM-guided group, each radiofrequency application lasted until the development of completely positive unipolar electrograms. In the CFM-guided group, a CF of 20 g (range, 10–30 g) and minimum force-time integral of 400 g were the targets for each radiofrequency application. The primary end point was freedom from any atrial tachyarrhythmia recurrence without antiarrhythmic drugs at 12-months of follow-up. Results: The cumulative freedom from recurrences at 12-months was 85% in the USM-guided group and 70% in the CFM-guided group ( P =0.031). The incidence of time-dependent and ATP-provoked early electrical reconnections between the left atrium and PVs, procedural time, fluoroscopic time, and average force-time integral, did not significantly differ between the 2 groups. The radiofrequency time for the pulmonary vein isolation was shorter in the USM-guided group than CFM-guided group but was not statistically significant ( P =0.077). Conclusions: USM was superior to CFM as an end point for radiofrequency energy deliveries during the pulmonary vein isolation in patients with paroxysmal atrial fibrillation in terms of the 12-month recurrence-free rate. Clinical Trial Registration: URL: https://www.umin.ac.jp/ctr/index.htm . Unique identifier: UMIN000021127.

Comparison of high‐power and conventional‐power radiofrequency energy deliveries in pulmonary vein isolation using unipolar signal modification as a local endpoint

“…USM is a qualitative indicator and indicates the real‐time evaluation of the transmural lesion creation while performing the PVI. It has been reported that the USM is a useful guide for the endpoint of each RF application while performing the PVI 5‐7,19 …”

“…Every single RF delivery was performed with a 10 to 20 g contact force (CF) and was continued for at least 5 seconds (5‐10 seconds) after the unipolar atrial electrogram that was recorded by the ablation catheter, which always demonstrated a positive‐negative morphology before the ablation, had become completely positive (USM; Figure 1). 6 …”

“…Every single RF delivery was performed with a 10 to 20 g contact force (CF) and was continued for at least 5 seconds (5-10 seconds) after the unipolar atrial electrogram that was recorded by the ablation catheter, which always demonstrated a positive-negative morphology before the ablation, had become completely positive (USM; Figure 1). 6 In the HP group, the power output was 50 W. Every single RF delivery was performed with a 5 to 20 g CF (target 10 g) and was continued for 3 to 5 seconds after the USM for the segments other than those adjacent to the esophagus. When the CF was >15 g or the ablation catheter was nearly perpendicular to the atrial wall, the RF delivery was continued for only 3 seconds after the USM.…”

“…5 The indifferent electrode was used as the cathode and was located at the level of the inferior vena cava. 6 The settings of the automated ablation tag marking (VisiTag) were as follows: stability <2.5 mm for 3 seconds; CFmin was 25% of time ≥3 g; tag size was 2 mm; and a white-colored tag was assigned when the ablation index (AI) was >320 and a red-colored tag when the AI was >380. VisiTag was not utilized as a guide for the RF delivery but as one of the anatomical pieces of information of the potential site of a residual LA-PV electrical connection after a circumferential RF application around the ipsilateral PVs.…”

“…4 R morphology achievement, the so-called the unipolar signal modification (USM), has been reported as a useful guide for the endpoint of each RF application and provides a real-time evaluation of the transmural lesion creation while performing the PVI. [5][6][7] During RF ablation, a lesion is created by resistive heating followed by conductive heating. Resistive heating immediately causes irreversible myocardial tissue injury with cellular death, whereas conductive heating passively extends to deeper tissue layers causing potential reversible tissue damage.…”