Introduction:

Pulsed field ablation (PFA) is a novel, nonthermal ablation technology with high myocardial selectivity, creating microscopic pores in the cell membranes. Currently, only 1 PFA ablation system has CE certification for treatment of paroxysmal atrial fibrillation (AF). Ablation of extra-pulmonary vein (PV) tissue could improve outcome in selected patients. Only very limited data on PFA ablation of extra-PV tissue is available. No data on PFA ablation of the left atrial (LA) appendage (LAA) is available.

Case: 

A 51-year-old patient with persistent AF for 9 years and status post 3 PV isolation (PVI) procedures had highly symptomatic (EHRA III-IV) AF recurrences requiring cardioversion under amiodarone. Considering age and symptoms, „off label“ therapy with PFA was recommended. Using a pentaspline catheter, high-density, bipolar voltage LA mapping demonstrated persistent PV isolation and absence of low voltage zones or fractionated electrograms (Figure, A+C). Bidirectional block was demonstrated using pacing manoeuvres. Despite apparent persistent PV isolation, all PVs were ablated again using PFA to eliminate any concealed conduction. After PV ablation, AF could easily be induced with burst stimulation. As agreed beforehand with the patient, the posterior wall, roof and mitral isthmus were successfully ablated using PFA (Figure, B+D). Still, AF could be induced. The LAA now showed a regular tachycardia with a cycle length of 170 ms, whilst both atria remained passively in AF. Assuming a LAA origin, the LAA base was successfully ablated using PFA. However, after a few minutes of LAA isolation, LAA reconduction was recorded on the pentaspline catheter. Extensive voltage mapping showed complete ablation of the LAA base, with reconduction in the LAA apex, suggesting an epicardial connection (Figure, E+F). Bidirectional reconduction was demonstrated using pacing manoeuvres. A deeper LAA ablation using the 35-mm diameter catheter was not possible for sizing and for safety reasons. After LAA ablation, no tachycardia could be induced anymore.

Conclusions:

PFA can easily and safely ablate extra-PV tissue. LAA ablation using PFA with the target to isolate is feasible but should be performed with caution.

Figure:

Panels A+C: postero-anterior (A) and left posterior oblique (C) view of LA, with bipolar voltage map (magenta: >0,5 mV, all other colours: <0,5 mV) demonstrating persistent PV isolation before PV ablation using PFA. Circular, pentapolar catheter: projection of PFA ablation catheter locations during extra-PV tissue ablation of roof (1), posterior wall (3) and mitral isthmus (1).

Panels B+D: postero-anterior (B) and left posterior oblique (D) view of LA, with bipolar voltage map (magenta: >0,5 mV, all other colours: <0,5 mV) demonstrating complete ablation of roof, posterior wall and mitral isthmus after extra-PV tissue ablation using PFA. Circular, pentapolar catheter: projection of PFA ablation catheter locations during extra-PV tissue ablation of roof (1), posterior wall (3) and mitral isthmus (1).

Panels E+F: antero-posterior (E) and left anterior oblique (F) view of LA, with bipolar voltage map (magenta: >0,5 mV, all other colours: <0,5 mV) demonstrating complete ablation of the base of the LAA using PFA. The magenta colour in the apex of the LAA suggests an epicardial connection.