Interval vs non-interval pulsed-field ablation: reduced microembolic signals and size in a porcine in vivo model

Background

Microembolic signals (MES) are observed in carotid Doppler during pulsed-field ablation (PFA) and may contribute to silent cerebral embolism. The effects of pulsing interval versus continuous delivery (Non-interval) and catheter contact on MES have not been systematically quantified.

Purpose

To evaluate, in an in vivo model, the impact of pulsing interval versus continuous delivery and catheter contact on MES.

Methods

Eight pigs underwent left-atrial PFA at four sites (LAA, RSPV, IPV = Contact, LA free-space = Non-contact) using a circular over-the-wire pulsed-field ablation catheter. At each site, four pulses were delivered either Interval (1-min apart) or Non-interval (continuous).

MES assessment: a continuous-wave Doppler probe was fixed on the common carotid artery for uninterrupted acquisition. On color Doppler, high-intensity spikes on the velocity display were identified as MES (Fig. 1A); spikes were confirmed on the extracted raw waveform from the Doppler-shift component (Fig. 1B) and counted across the four-shot set per condition. Sizes were prespecified and binned (0–10/10–20/20–30/30–40/40–50 µm).

Analysis: animal-by-site pairs served as the unit (n = 32 pairs). Paired, within-animal/site comparisons estimated incidence rate ratios (IRR) with 95% confidence intervals. Primary endpoints: IRR for MES counts and MES size (median [IQR] from pooled MES and composition) for Interval vs Non-interval. Secondary endpoint: IRR for Contact vs Non-contact. This paired design minimizes between-animal variability and controls for local anatomic/flow factors, isolating delivery-strategy effects.

Results

Interval reduced MES vs Non-interval: overall IRR 0.72 (95% CI 0.67–0.77). Site-wise IRRs: RSPV 0.63 (0.56–0.72), IPV 0.24 (0.20–0.30), LA free-space 0.54 (0.47–0.61), LAA 1.20 (1.08–1.33) (Fig. 2A). MES size was smaller with Interval: 19.3 µm [14.0–25.5] vs 21.1 µm [14.5–26.9], p<0.001 (Fig. 2B). Secondary (Contact): overall 1.15 (1.07–1.28); during Interval 1.14 (1.01–1.37); during Non-interval 1.17 (1.05–1.30), indicating higher MES with contact across delivery strategies. Findings were consistent across sites except for LAA, where interval delivery did not reduce MES, suggesting site-specific hemodynamics may modulate embolic generation.

Conclusions

In a standardized porcine PFA model, 1-min interval delivery significantly reduces MES burden and MES size and may represent an effective, workflow-compatible approach to mitigate PFA-related cerebral embolic risk. Prospective clinical validation and linkage to neurological outcomes are warranted.Figure 1Figure 2