Prevention of cardiac tamponade during CLOSE-protocoll guided ablation of atrial fibrillation
Authors: Krahnefeld O , Poley P , Agdirlioglu T , Krahnefeld C , Weil J 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
Catheter ablation (CA) with radiofrequency (RF) energy using the CLOSE protocol has proven safety and efficacy in a large prospective multicenter study(1) with the rate of pericardial tamponade (PT) as low as 0.9%. PT may still become hazardous in the era of uninterrupted anticoagulation and may require urgent surgical repair. Steam pop is the major cause of PT during Pulmonary vein Isolation (PVI) with RF ablation and is usually preceded by steep impedance rise measured between tissue and tip of the RF catheter. The STOCKERT SMARTABLATE RF Generator as a core part of technology for CLOSE protocol guided PVI offers the opportunity to automatically stop RF energy delivery within 0.5 seconds if catheter impedance rises above a predefined value: impedance spike cut off (ISCO). The standard – manufacturer recommended – value for ISCO is 50 Ω per 0.5 seconds.

Purpose
To investigate the effect of reduced ISCO during CLOSE protocol guided catheter ablation of AF on the occurrence of acute PT and pericardial effusion (PE) in a large single center series.

Methods
We performed CLOSE protocol guided PVI procedures using Biosense Webster CARTO PRIME 3D navigation system, Smarttouch SF ablation catheter, VIZIGO steerable sheath, invasive blood pressure measurement via radial artery. We changed the STOCKERT SMARTABLATE generator settings to ISCO of 25Ω per 0,5 seconds. Cut off during the ablation procedure by ISCO led the operator to reduce contact force, angulation/orientation of catheter/steerable sheath, changing to jet ventilation if mechanical ventilation was present. Investigation for PT by echo was performed for every drop &lt;90mmHg systolic blood pressure. PE detection immediately after and the day after ablation procedure was performed by transthoracic echo. A retrospective analysis of all CLOSE protocoll procedures was performed. Statistical analysis was performed on the evaluable population.

Results
During 43 months of observation we performed 980 CLOSE protocol guided procedures: 516 PVI only, 464 PVI with additional ablations (VT, cavotricuspid isthmus, slow pathway, additional LA lines, ethanol ablation of vein of marshall). We observed 4 (0.4%) PT immediately at the end of the procedure and no additional relevant PE the day after CA. Of the 4 PT, 1 patient needed urgent surgical repair and 3 were managed conservatively with pericardiocentesis and retransfusion.

Conclusions
CLOSE protocol guided PVI is an effective and safe intervention for treatment of AF. The VISITAX trial reported 3 events of PT per 329 patients (0.9%). By reducing ISCO to 25 Ω per 0,5 seconds, we found less than half of the rate of PT (0.4%) compared with the VISITAX trial. The generator cut off at ISCO of 25 Ω per 0.5 seconds automatically stops a potentially dangerous ablation and can indicate potientially dangerous ablation sites. Our data are limited due to the retrospective monocentric design and therefore should be evaluated prospectively.