Mp-453081-7 a comparison of left circumflex coronary vasospasm between radiofrequency ablation and pulsed field ablation at the mitral isthmus

Pulsed field ablation (PFA) is a nonthermal energy modality that largely spares collateral structures like the esophagus and phrenic nerve. However, a recent study indicates that subclinical coronary artery vasospasm is common during PFA of the cavo-tricuspid isthmus. There is also a case report of left circumflex artery (LCx) vasospasm during PFA at the mitral isthmus (MI). To determine the frequency of LCx vasospasm during PFA on the lateral MI and compare to RFA. In a prospective, consecutively enrolled cohort of patients undergoing AF ablation under deep sedation, diagnostic coronary angiography was performed via right femoral arterial access before, during, and after endocardial ablation on the lateral MI with either a PFA catheter (Farawave, Boston Scientific Inc) or an irrigated RFA catheter (Thermocool, Biosense-Webster Inc). When vasospasm was identified on angiography, it was monitored for clinical remission and hemodynamic changes and intervention with nitroglycerin administered if refractory to upfront supportive care. A total of 19 patients received PFA on the lateral MI with acute bidirectional block: 11 along the superior MI (1-2 o’clock on the annulus) and 8 along the inferior MI (3-5 o’clock on the annulus). In total, 7 patients experienced LCx vasospasm (2 mild, 3 moderate, 1 severe). By site, 7 of 11 (64%) and 0 of 8 (0%) were at the superior or inferior MI, respectively. In comparison, 9 patients underwent RFA of the MI (all at the superior MI with coronary sinus lesions in 3 patients), during which there were no instances of LCx spasm. Of note, 5 of 9 patients also received MI PFA due to the absence of MI block after first pass RFA; 3 of these 5 patients did demonstrate LCx spasm during PFA. In none of the instances of MI spasm were there any symptoms or hemodynamic compromise. ECG changes were seen in 1 patient: ST elevations with severe LCx spasm. While PFA confers an important degree of tissue preferentiality and enhanced safety compared to thermal ablation for esophageal/phrenic damage and pulmonary vein stenosis, our data indicate that PFA can cause reversible (mostly) subclinical LCx spasm during MI ablation. Vasospasm occurred during superior MI ablation while inferior MI PFA did not cause spasm; this may be related to the proximity of the PFA catheter to the LCx along its superior-inferior course. Conversely, RFA of the MI does not appear to be associated with a significant risk for LCx spasm.