Hd grid

The three-dimensional geometry of the LA and PVs was reconstructed using either the EnSite NavX (St. Jude Medical, St. Paul, MN, USA) or CARTO (Biosense Webster, Irvine, CA, USA) navigation system. High-density bipolar voltage mapping was performed using a multispline mapping catheter (PentaRay, Biosense Webster; or HD grid, Abbott; or Inquiry AFocus, St. Jude Medical). For the purpose of comparison, a peak-to-peak bipolar electrogram amplitude <0.5 mV was defined as the low-voltage threshold for all maps in accordance with previous studies.^{12 ,14} (link) The PV ostium was identified as the point of maximal inflection between the PV wall and LA wall, and the PV antrum was defined as the region proximal to the PV ostium excluding the PVs. In patients with a common PV, we defined the second branch of common trunk as PV ostium as described in previous study.⁹ (link) The LA posterior wall surface area was defined as the area bordered by the PV lesions and two lines connecting the most superior- and inferior-most aspects of the circumferential ablation lines, respectively. The surface areas of the isolated left- and right-sided PV antra and non-ablated posterior wall were quantified (Supplementary material online, Figure S1). The CARTO and Ensite systems automatically calculated the surface area and the distance from manually selected points.

Under conscious sedation, the following catheters were introduced via right femoral vein: (1) a decapolar catheter (Abbott Medical, MN, USA) within the coronary sinus, (2) a 3.5‐mm open irrigated‐tip ablation catheter (Flexability catheter, Abbott Medical, MN, USA). The multielectrode catheter HD Grid was utilized (Abbott Medical; MN, USA) for EGM acquisition. Every patient had given written informed consent before the study.

Eight consecutive patients undergoing ablation for AF (five paroxysmal, three persistent) were prospectively enrolled at our institution. The electro‐anatomical maps of both atria were built using the HD Grid mapping catheter (Abbott Laboratories, North Chicago, IL, USA) ensuring a density of at least 1500 EGMs per chamber. Inclusion criteria were age > 18 years, documented AF episodes recorded on 12 lead ECG undergoing catheter ablation for clinical indication as per 2020 ESC guidelines.¹³ Exclusion criteria were: previous left atrial catheter ablation, structural valvular disease, known primary electrical heart disease, thyroid and pulmonary disease, and use of amiodarone in the past 2 months. Each patient underwent a complete transthoracic echocardiography evaluation. Antiarrhythmic drugs were discontinued at least five half‐lives before the procedure. Patients with persistent AF were cardioverted to sinus rhythm (SR) with external DC shock at the time of the procedure. The study was approved by the local Ethical Committee on Human Research.

For recurrences of symptomatic AF redo procedures were performed. Following double transseptal puncture mapping was performed with the EnSite Velocity or Precision (Abbott) or Rhythmia HDx (Boston Scientific) or CARTO (Biosense Webster) mapping systems. Mapping of the LA and PVs was performed with multipolar catheters: AFocus, HD Grid (Abbott), Orion catheter (Boston Scientific) or Lasso Nav or Pentaray (Biosense Webster). Ablation was performed with irrigated tip catheters: Tacti-Cath SE (Abbott), Intellanav OI MIFI (Boston Scientific) or Smarttouch (Biosense Webster). Cardioversion was performed before left atrial mapping in case of AF. During the redo procedure, the pulmonary veins were assessed during coronary sinus pacing and gaps were consequently isolated using radiofrequency applications of 35 W (anterior wall) or 30 W (posterior wall) of 60 s.