Index procedure: EIVM
After written consent was obtained, procedures were performed under general anesthesia and uninterrupted anticoagulation (uninterrupted direct oral anticoagulants and vitamin-K antagonists with an international normalized ratio target of 2–3, 120 U/kg of intravenous heparin given after femoral puncture for activated clotting time target > 300). EIVM was performed as described.9Briefly, after transseptal access and high-density LA bipolar voltage mapping performed during sinus rhythm (SR), AF or LA flutter, the CS was cannulated with a standard SL0 or a steerable Agilis sheeth. To visualize the VOM ostium, non-selective CS angiography (anteroposterior) was performed with a multipurpose coronary angiography 5F LIMA catheter. When the VOM ostium could not be seen, selective CS angiography with a Swan-Ganz balloon catheter was performed at the median and proximal CS with 30° left and right anterior oblique views. The VOM was cannulated with the LIMA catheter and a straight Whisper guidewire (Boston Scientific, Marlborough, MA) was inserted in the Marshall venous network over a 2.00- to 6.00-mm MiniTrek balloon angioplasty catheter (Abbott, Chicago, IL). After VOM balloon occlusion, injections of 3 mL of 96% ethanol were administered sequentially, separated by injections of 3 mL contrast agent, until an aspect of the LA myography was seen, indicating ethanol penetration into the LA myocardial tissue.