This prospective study was approved by the ethical review board of Mie University Hospital (certificate number 3,038), and all patients provided written informed consent. All methods were performed in accordance with the Declaration of Helsinki. All patients were recruited from the Department of Cardiology, Mie University Hospital between August 2018 and September 2019. We recruited 101 patients who were admitted to the hospital for AF catheter ablation 13.
We obtained clinical information, laboratory, and imaging data at baseline and follow-up after catheter ablation. Detailed clinical information, including age; sex; height; weight; blood pressure; heart rate; medical history, such as hypertension, hyperlipidemia, and diabetes mellitus; history of transient ischemic attack and/or stroke; and medication at baseline, was collected.
Catheter ablation was performed as described previously14. After obtaining informed consent, an electrophysiological study was performed in the post-absorptive state under light sedation. After internal jugular and femoral vein punctures, a heparin bolus (100 U/kg) was administered, and continuous infusion of heparin was provided thereafter to maintain an activated clotting time between 250 and 350 s. A diagnostic duodecapolar catheter was placed in the coronary sinus via the jugular vein. Three long sheaths were inserted through the femoral vein and introduced into the left atrium (LA) through a single trans septal puncture guided by intracardiac echocardiography. An eicosapolar circumferential catheter (Lasso 2515, Biosense Webster, Diamond Bar, CA, USA) and a multispline mapping catheter (PentaRay, Biosense Webster) were introduced into the LA through the trans septal long sheaths.
All imaging was performed using a biplane flat panel detector angiographic suite (Allura Xper FD10/10 Angio system; Philips Healthcare, Best, the Netherlands). Electroanatomical mapping was performed using the CARTO3 mapping system (Biosense Webster). Radiofrequency ablation was performed with an irrigated catheter (EZ Steer Thermocool, Biosense Webster) using 0.9% normal saline and a point-by-point technique. Extensive encircling pulmonary vein isolation (EEPVI) was performed in patients with paroxysmal AF, and entrance and exit blocks were documented in all patients using Lasso2515 and PentaRay multipolar catheters. In addition to EEPVI, patients with persistent AF received LA posterior wall isolation. Additional linear ablation was performed along the LA roof to connect the left superior pulmonary vein to the right superior pulmonary vein and linear ablation along the LA floor to connect the inferior margin of the left inferior pulmonary vein to the right inferior pulmonary vein to obtain a block into the posterior wall. A bidirectional block was confirmed across all linear ablations using differential pacing techniques. If common atrial flutter was induced by atrial tachycardia pacing, cavotricuspid isthmus line ablation was performed in patients with paroxysmal AF and persistent AF.
Magnetic resonance imaging (MRI) protocol
MRI studies were performed at 1 to 3 days (baseline) and 6 months after ablation (follow-up) with a 3T MR unit (Ingenia, Philips Medical System, The Netherlands) using a 32-channel phased-array head coil13. We used diffusion-weighted imaging (DWI), three-dimensional (3D) fluid-attenuated inversion recovery (3D-FLAIR), 3D double inversion recovery (3D-DIR), and 3D T1-weighted imaging (3D-T1WI) to detect microemboli15, 16. Acute microinfarctions were diagnosed using DWI images, whereas chronic microinfarctions were evaluated using 3D-DIR, 3D-FLAIR, and 3D-T1WI images. SWI was used to detect CMBs.
3D-DIR parameters were as follows: FOV, 250 mm; matrix, 208 × 163; thickness, 1.3 mm; TR (ms)/TE (ms), 5,500/247; TI (ms), 2,550/450; NEX, 2; and acquisition time, 5 min 13 s.
3D-FLAIR parameters were as follows: FOV, 250 mm; matrix, 256 × 184; thickness, 1.14 mm; TR (ms)/TE (ms), 6,000/390; TI, 2,000 ms; NEX, 2; and acquisition time, 4 min 42 s.
3D-T1WI imaging used turbo-field echo sequence and the following parameters: FOV, 260 mm; matrix, 288 × 288; thickness, 0.9 mm; TR (ms)/TE (ms), 8.4/4.7; NEX, 1; FA, 10°; and acquisition time, 4 min 56 s.
SWI parameters were as follows: FOV, 230 mm; matrix, 384 × 300; thickness, 2 mm; TR (ms)/TE (ms), 31/7.2; NEX, 1; FA, 17°; and acquisition time, 4 min 52 s.
And DWI parameters: FOV, 220 mm; matrix, 112 × 168; thickness, 3 mm without gap; TR (ms)/TE (ms), 5800 /87; b value = 1,000 s/mm2; NEX, 1; three orthogonal diffusion directions; and acquisition time, 1 min 10 s.
CMBs and cortical superficial siderosis, white matter hyperintensity (WMH) and lacunar infarcts, and acute microinfarctions were evaluated using SWI, 3D-FLAIR, and DWI, respectively17. Periventricular and deep WMHs were assessed according to the Fazekas rating scale18. MRI images were thoroughly analyzed by two trained neurologists (Y.H. and N.K.) who were blinded to the clinical data.
For the analyses of the differences in demographic characteristics, the Mann-Whitney U test and the χ-square test were used. To compare the difference in medical history between the group with newly detected de novo CMBs (positive group) and the group without de novo CMBs (negative group), the χ-square test was used. To compare the difference in DWI-positive lesions and Fazekas scores between the two groups, the Mann-Whitney U test was used. Statistical analyses were performed using the Statistical Package for the Social Sciences Statistics software version 27 (IBM Corporation, Armonk, NY, USA).