Word of caution: clinically apparent coronary spasm following pulsed field cavotricuspid isthmus ablation despite nitroglycerin prophylaxis - a case report.

Background: Pulsed field ablation (PFA) is a novel ablation technology. A rare side-effect is the occurrence of mostly subclinical coronary spasms when PF energy is applied in proximity to coronary arteries. However, it has been described that prior application of nitroglycerin attenuates these effects.

Case summary: A 75-year-old female underwent catheter ablation with a penta-spline PFA catheter. After pulmonary vein isolation, the PFA catheter was positioned on the cavotricuspid isthmus (CTI). Before ablation, 2 mg of nitroglycerin was administered intravenously. After 10 PFA applications, the CTI was successfully blocked. After a timely delay of 95 s, a clinically apparent vasospasm with ST elevations in leads II, III, and aVF on the electrocardiogram was noticed. Shortly thereafter, the clinical course was aggravated by haemodynamically relevant non-sustained ventricular tachycardias (nsVTs) followed by asystole, requiring pacing and additional 4 mg of nitroglycerin. Twelve minutes later, a stable sinus rhythm with normalized ST segments was restored. The spasm resolved without any sequelae. Post-procedural coronary angiogram showed right dominant coronary circulation.

Discussion: This is the first report of a timely delayed, clinically apparent coronary spasm with a presentation of haemodynamically relevant nsVT and asystole despite the prophylactic application of high-dose intravenous nitroglycerin prior to PFA along the CTI. Subclinical vasospasm during PFA at the CTI has been described before. Severe spasms could be prevented by nitroglycerin. A word of caution needs to be raised as prophylactic nitroglycerin did not prevent the haemodynamically relevant coronary spasm in the here reported patient. Until now, it remains unclear how much later such effects may occur; therefore, patients should be monitored closely.