Pulsed-field ablation safe for AF but may cause innocuous coronary spasm during ablation of mitral isthmus: JAMA

"Coronary artery vasospasm was provoked in 41.2% of Farapulse PFA procedures at the posterolateral mitral isthmus," the researchers reported in their small case series. "Instances of spasm reached 77.8% when the ablation line was situated superiorly along the mitral isthmus, but did not happen in any of the eight cases where the line was situated inferiorly."

Coronary spasms were not seen in any of the nine patients undergoing more conventional radiofrequency ablations (RFAs). Of another five RFA patients who failed to achieve conduction block and crossed over to PFA, coronary spasms occurred in three: one self-resolving severe case and two mild cases.

The researchers noted that 90% of spasms were subclinical -- arrhythmias, no ST-segment elevation, or ventricular wall motion abnormalities -- remaining 20% needed nitroglycerin administration. One instance of dynamic ST-segment changes without hemodynamic instability was noted. The median time to remission was 5 minutes.

The prospective study enrolled consecutive adult patients receiving their first-ever RFA or PFA of the mitral isthmus during catheter ablation of AF in 2022 with acute follow-up at a single referral European centre.

Using either a multielectrode pentaspline PFA catheter (endocardial ablation) or a saline-irrigated RFA catheter, a posterolateral mitral isthmus line was created. Simultaneous diagnostic coronary angiography was conducted before, during and after catheter ablation. Nitroglycerin was planned for spasms persisting beyond 20 minutes or for significant electrocardiographic changes.

The severity and frequency of left circumflex arterial vasospasm were monitored and assessed. Time to remission and any need for nitroglycerin administration was also assessed and monitored.

26 patients were included (73% were male, and the mean age was 65.5 years). Patients underwent either PFA (n = 17) or RFA (n = 9) along the mitral isthmus.

The researchers reported the following findings:

• Coronary spasm was observed in 41.2% of patients undergoing PFA: in 77.8% of patients when the mitral isthmus ablation line was situated superiorly and in 0 of 8 when situated inferiorly.
• Coronary spasms did not occur in any of the 9 patients undergoing RFA.
• Of 5 patients in whom crossover PFA was performed after RFA failed to achieve conduction block, coronary spasm occurred in 60% of the patients.
• Most instances of spasm (90%) were subclinical, with 20% requiring nitroglycerin administration. The median time to resolution of spasm was 5 minutes.

"When creating a mitral isthmus ablation line during catheter ablation of atrial fibrillation, adjacent left circumflex arterial vasospasm occurred frequently with PFA and not RFA but was typically subclinical," the researchers concluded.

Reference:

Zhang C, Neuzil P, Petru J, et al. Coronary Artery Spasm During Pulsed Field vs Radiofrequency Catheter Ablation of the Mitral Isthmus. JAMA Cardiol. Published online November 29, 2023. doi:10.1001/jamacardio.2023.4405