October 1, 2007Open Access

Noninvasive Assessment of Atrial Substrate Change after Wide Area Circumferential Ablation: A Comparison with Segmental Pulmonary Vein Isolation

Q: What is the clinical evidence from this study?

Study design: Cohort. Population: Paroxysmal atrial fibrillation (n=40). Intervention: Wide Area Circumferential Ablation (WACA) vs. Segmental Pulmonary Vein Isolation (PVI). Primary outcome: Change in P wave duration (PWD) at 24 hours (p=0.003).

Key Result

Wide area circumferential ablation significantly prolonged P wave duration by 11 ms and reduced P wave energy, whereas segmental pulmonary vein isolation produced no significant changes.

Study Design

Type

Cohort (n=40)

Blinding

Single-blind

Multicenter

Yes

PICO

Population

Paroxysmal atrial fibrillation (n=40)

Intervention / Comparator

Wide Area Circumferential Ablation (WACA) vs Segmental Pulmonary Vein Isolation (PVI)

Primary Outcome

Change in P wave duration (PWD) at 24 hours, p=0.003

Main Result

Absolute Event Rate: 11% vs 3%

p-value: p=0.003

Limitations

Loss of data resulted in exclusion of some patients, leading to small numbers for predictive analysis
Patients were not part of a randomized controlled trial
The groups were nonconsecutive cohorts with procedures performed at different centers
Direct anatomic correlates with substrate modification from WACA are inferred but cannot be confirmed from this study

Abstract

BACKGROUND: The wide area circumferential ablation (WACA) approach to atrial fibrillation is thought to result in 'substrate modification' perhaps related to autonomic denervation. We examined this prospectively by comparing WACA and segmental pulmonary vein isolation (PVI) using noninvasive surrogate markers. METHODS: Heart rate variability (HRV) and signal averaged P wave (SAPW) data were derived from high-resolution (HR) recordings ('SpiderView' ELA Medical) made in sinus rhythm immediately before and 24 hours after ablation. RESULTS: Forty patients recruited (20 WACA; 20 PVI); cohorts were comparable. WACA caused marked SAPW change: P wave duration (PWD) (1494.6 ms to 1605.9 ms; P = 0.003), root mean square (RMS) (4.40.4microV to 2.80.4; P = 0.001) and energy content (30-150 Hz; 20.4 3.6microV(2)/s to 13.72.4; P = 0.001). No significant change was seen after PVI. Heart rate increased after WACA and PVI (61.4 to 73.5 P = 0.001; 69.5 to 75.0 P = 0.07, respectively). HRV was significantly influenced after WACA: low frequency power (LF) 5.7(0.4) to 3.6(0.4); P = 0.001), high-frequency power (HF) 4.6(0.4)-3.4(0.3); P = 0.024, and after PVI: LF 5.4(0.3) to 4.3(0.3); P = 0.024. HF: 4.4(0.4) to 3.0(0.4); P = 0.018). CONCLUSIONS: HR recordings exhibit change in HRV after WACA and PVI. Marked change in both HRV and SAPW is observed after WACA. SAPW variables provide a measure of atrial substrate change after WACA unrelated to autonomic denervation.

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Cite This Study

Redfearn et al. (Mon,) conducted a cohort in Paroxysmal atrial fibrillation (n=40). Wide Area Circumferential Ablation (WACA) vs. Segmental Pulmonary Vein Isolation (PVI) was evaluated on Change in P wave duration (PWD) at 24 hours (p=0.003). Wide area circumferential ablation significantly prolonged P wave duration by 11 ms and reduced P wave energy, whereas segmental pulmonary vein isolation produced no significant changes.

synapsesocial.com/papers/6a12c0c592637892a9a7311e https://doi.org/https://doi.org/10.1111/j.1542-474x.2007.00182.x