Background:

Thermal ablation modalities, like cryoablation can cause bronchial damage during left atrial (LA) ablation. Hemorrhagic lesions, severe cases of atrio-bronchial fistula and life-threatening bronchial bleedings have been reported. Pulsed field ablation (PFA) for paroxysmal atrial fibrillation (PAF) is a novel, commercially available, non-thermal ablation modality. There are no pre-clinical or clinical data available, whether PFA can cause bronchial damage. We investigated real-world data on possible bronchial injury after clinical routine pulmonary vein (PV) isolation (PVI) using PFA for PAF.

Methods:

A pre-interventional computed tomography (CT) showing the respiratory tract adjacent to the LA was obtained. Oral anticoagulation was interrupted on the day of the procedure and on the first day after the procedure. Patients received intravenous heparin with an ACT goal of >325 seconds during the procedure. Pre- and post-ablation, a high-density, bipolar voltage, 3D map (Biosense Webster) of the LA was obtained. PFA was performed according to standard protocol, with a minimum of 8 applications per PV. A Cook straight tip, extra-stiff wire was placed deep into each PV to guide and stabilize the ablation catheter. Patients underwent PVI without pre-procedurally intended additional lesions. Additional ablations were left at operator’s discretion. One day after PVI, a diagnostic bronchoscopy under sedation with propofol was performed by an experienced pulmonologist, no biopsies were taken. All patients were scheduled for a 30-day clinical follow-up in the outpatient department. Blood samples were collected before the procedure, on the first day after the procedure and during the outpatient follow-up after 30 days.

Results:

In 30 PAF patients (age 63±10 years; 47% male; CHA₂DS₂-VASc-Score 2 [IQR 1-3]), uncomplicated PFA was performed, with all PVs acutely isolated. Post-ablation, all voltage maps consistently showed extensive antral PV lesions. In 1 patient with roof dependent flutter, a roof line was intentionally created with 8 additional applications. ACT was >325 seconds directly after transseptal puncture in all patients. The clinical course was uneventful, none of the patients reported chest discomfort, coughing or hemoptysis. No relevant decrease in hemoglobin levels were measured. All patients underwent uncomplicated bronchoscopy, there were no visible thermal lesions or ulcers. In 12 patients (40%), small amounts of blood clots were seen in multiple segments without signs of active bleeding. At 30-day follow-up, no patient reported chest discomfort, coughing or hemoptysis. There were no procedure-related complications, hemoglobin levels remained stable.

Conclusion:

In a real-world, non-clinical study setting, PVI using PFA for PAF seems to be a safe modality for catheter ablation near the bronchial system. PFA using a straight tip, extra-stiff wire can lead to asymptomatic blood oozing in the bronchial system without clinical relevance at 30-day follow-up.

Figure:

Postero-anterior view of the LA before (left) and after (right) ablation with the course of the trachea and main bronchi (dark grey) projected over the roof and posterior LA wall. The colours of the high-density, bipolar voltage, 3D map post-ablation (right) show the extensive antral ablation lesions (<0.5 mV) visualized as areas of non-magenta colours.