# Acute effect of cryoballoon pulmonary vein isolation on the signal-averaged P-wave

## TL;DR

This study shows that cryoballoon ablation for atrial fibrillation causes measurable changes in the P-wave, suggesting acute effects on atrial electrical activity.

## Contribution

The study introduces high-resolution ECG analysis to detect stepwise changes in atrial activity during pulmonary vein isolation.

## Key findings

- P-wave terminal force, complexity, and entropy decreased significantly after complete pulmonary vein isolation.
- Left pulmonary vein ablation showed more pronounced decreases in P-wave parameters compared to right vein ablation.
- High-resolution ECG can detect acute intraprocedural changes in atrial electrophysiology.

## Abstract

Cryoballoon ablation of atrial fibrillation alters a significant amount of vital myocardium contributing to its electrical activity. However, the effect of pulmonary vein isolation (PVI) on the P-wave is unclear. The study aimed to quantify P-wave changes following individual PVI using signal-averaged ECG analysis.

Unfiltered high-resolution (2,000 samples/second) ECGs were obtained for 5 min pre- and post-isolation of each pulmonary vein in 69 participants using 12 standard and 10 additional leads optimized for atrial electrical activity detection. Signal-averaged ECGs were computed and analyzed using custom software in Matlab. This study was registered at ClinicalTrials.gov (Identifier: NCT06061120).

Significant changes in ECG parameters were found. Following complete PVI, P-wave terminal force measured in lead V1 (3.08 ± 1.99 vs. 2.63 ± 1.76 mV*ms, p = 0.003), as well as P-wave complexity (2.05 ± 0.65 vs. 1.79 ± 0.51, p < 0.001) and sample entropy (0.210 ± 0.039 vs. 0.187 ± 0.028 au, p < 0.001), both averaged across all leads, decreased significantly. Ablation of the left pulmonary veins was associated with lower values in P-wave terminal force (3.07 ± 2.05 vs. 2.84 ± 1.88 mV*ms, p = 0.003), P-wave complexity (2.02 ± 0.64 vs. 1.90 ± 0.57, p = 0.003), and sample entropy (0.210 ± 0.039 vs. 0.197 ± 0.031 au, p < 0.001) after ablation. For ablation of the right pulmonary veins, a decline was observed in sample entropy (0.196 ± 0.031 vs. 0.190 ± 0.027 au, p = 0.046).

The observed changes in signal-averaged P-wave parameters during cryoballoon PVI may indicate acute intraprocedural effects on atrial electrophysiology. These exploratory findings suggest that high-resolution, non-invasive ECG recordings are capable to detect stepwise changes of electrical atrial activity, offering new perspectives for intraprocedural assessment of ablation effects.