Key result
Optimized pulsed field ablation achieves 100% chronic pulmonary vein isolation without catheter thrombus.
Why the study?
The study was motivated by the need to compare safety and efficacy of different pulsed field ablation waveforms and irrigation rates using a variable loop circular catheter for atrial fibrillation treatment.
Does a second-generation pulsed field ablation waveform (Seq2) with 30 mL/min irrigation improve ablation safety surrogates (catheter thrombus, microbubbles, thermal profile) while maintaining acute and chronic lesion efficacy compared with first-generation waveforms (Seq1 at 4 mL/min and 30 mL/min) in a porcine model?
Does a second-generation pulsed field ablation waveform (Seq2) with 30 mL/min irrigation improve ablation safety surrogates (catheter thrombus, microbubbles, thermal profile) while maintaining acute and chronic lesion efficacy compared with first-generation waveforms (Seq1 at 4 mL/min and 30 mL/min) in a porcine model?
In a preclinical porcine model, a faster second-generation pulsed field ablation waveform (3.8 seconds vs 20.6 seconds) with 30 mL/min irrigation maintained 100% chronic pulmonary vein isolation while eliminating catheter thrombus formation and minimizing microbubble generation.
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Captured external expert commentary on this paper, strongest first. Original sources are linked where available.
“In our early experience, VARIPULSE Pro has been exceptionally smooth and easy to use. The speed is particularly striking and contributes to more efficient procedures without compromising precision. The integration with CARTO mapping and intracardiac echocardiography (ICE) facilitate accurate positioning and consistent lesion delivery, contributing to a very positive procedural experience.”
“In our early experience, VARIPULSE Pro has been exceptionally smooth and easy to use. The speed is particularly striking and contributes to more efficient procedures without compromising precision. The integration with CARTO mapping and intracardiac echocardiography (ICE)facilitate accurate positioning and consistent lesion delivery4, contributing to a very positive procedural experience.”
Seq2 with higher irrigation may improve safety surrogates in pulsed field ablation; leaves open whether these gains translate to human atrial fibrillation procedures.
BACKGROUND: The variable loop circular catheter has been shown to be a safe, effective pulsed field ablation catheter for atrial fibrillation treatment. After the commercial launch of the initial waveform (Seq1), a new waveform (Seq2 30 mL/min ) was developed that reduces electrode surface temperature and ablation delivery time (20–3.8 seconds). This study compares the safety and efficacy of Seq1 versus Seq2 across 2 irrigation rates and 2 dosing conditions. METHODS: Twenty-four Yorkshire pigs were treated with pulsed field ablation using the variable loop circular catheter. Subjects were randomized into 3 pulse recipe/irrigation arms (Seq1 4 mL/min , Seq1 30 mL/min , and Seq 2 30 mL/min ). Each group was split into a 1× nominal and a 2×-dose group, resulting in 6 total study groups. Animals were monitored for 28±2 days postablation for follow-up remapping procedures before euthanization. Gross necropsy and histopathology were performed on day 28±2. RESULTS: In all groups, 100% acute and chronic pulmonary vein isolation effectiveness was observed, as indicated by transmural, circumferential, pulmonary vein lesions with no evidence of collateral injury. Transmurality in the left atrial appendage, LA roof, and posterior wall was 75% to 100% across all groups and absent at the mitral isthmus. No catheter thrombus/char was observed at Seq2 30 mL/min or Seq1 30 mL/min . With Seq1 4 mL/min , thrombus/char occurred in 25% (1×) and 100% (2×). Hemolysis and myocardial injury marker changes were similar between all groups, with a notable increase in the 2× groups. On echocardiography, Seq2 30 mL/min microbubbles were rated as few or none, while Seq1 4 mL/min and Seq1 30 mL/min were mostly rated moderate or shower. CONCLUSIONS: Consistently durable pulmonary vein isolation was observed across all groups, including Seq1 4 mL/min , Seq2 30 mL/min , and Seq1 30 mL/min across both dosing conditions. Seq2 30 mL/min was associated with a reduced ablation delivery time (3.8 seconds), zero catheter thrombus formation, and few microbubbles. Higher irrigation flow in Seq1 30 mL/min also mitigated catheter thrombus formation but did not reduce microbubble generation.
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Biase et al. (2026) studied Preclinical porcine model for atrial fibrillation pulsed field ablation (n=24). Variable loop circular catheter pulsed field ablation using Sequence 2 waveform with 30 mL/min irrigation (Seq2 30 mL/min) vs. Sequence 1 waveform with 4 mL/min irrigation (Seq1 4 mL/min) or 30 mL/min irrigation (Seq1 30 mL/min) at 1x and 2x doses (20.6 seconds duration) was evaluated on Acute (day 0) and chronic (day 28±2) pulmonary vein isolation effectiveness (transmural, circumferential PV lesions and bidirectional electrical block) (p=>0.05). Pulsed field ablation with Seq2 achieved 100% chronic pulmonary vein isolation in 3.8s with 0% catheter thrombus vs 25%-100% in Seq1.
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