Identification and electrophysiological characterization of early left atrial structural remodeling as a predictor for atrial fibrillation recurrence after pulmonary vein isolation.

BACKGROUND: Voltage-guided substrate ablation following pulmonary vein isolation (PVI) improves atrial fibrillation (AF) ablation outcomes. However, by setting an upper voltage cutoff of 0.5 mV during sinus rhythm (SR) to guided substrate ablation using electroanatomic voltage mapping (EAVM), mildly affected low-voltage area (maLVA) may be undetected. We sought to determine the optimal bipolar voltage cutoff to identify maLVA, its electrogram complexity, and the implication on ablation outcome. METHODS AND RESULTS: Left atrial (LA) EAVMs were obtained in patients without AF and structural heart disease (control) to devise a voltage cutoff to identify maLVA. Subsequently, we investigated 100 patients without low-voltage area (LVA) of < 0.5 mV who underwent PVI alone. In our 6 control cohorts, 95% of LA regional bipolar voltage was > 1.17 mV. maLVA, defined as <1.1 mV, was present in 43% of AF patients, associated with higher prevalence of abnormal electrograms (44.1% vs. 4.4%, P < 0.001). During a median of 2.4 years, patients with maLVA had higher recurrence rate (Log-rank P < 0.001), and maLVA was an independent predictor for recurrence in a multivariate analysis (hazard ratio [HR] 3.944; 95% confidence interval [CI] 1.292-12.042; P = 0.016). CONCLUSIONS: A control-derived LA voltage cutoff of <1.1 mV for EAVM in SR reveals maLVA, harboring abnormal electrograms, as an independent predictor for recurrences after PVI alone in patients without LVA (< 0.5 mV). Adjunctive maLVA-guided substrate ablation targeting mildly remodeled and potentially arrhythmogenic LA substrate may further improve the long-term outcome of AF ablation.

Long-Term Outcome of Left Atrial Voltage-Guided Substrate Ablation During Atrial Fibrillation: A Novel Adjunctive Ablation Strategy.

INTRODUCTION: Left atrium (LA) low voltage area (LVA) on 3-D electroanatomic bipolar voltage mapping (EAVM), as a surrogate for scar, is associated with poor AF ablation outcome. We evaluated the long-term outcome of an LVA-guided atrial fibrillation (AF) substrate modification strategy as an adjunct to pulmonary vein isolation (PVI). METHODS AND RESULTS: Two hundred and one consecutive patients with AF (82% persistent/Non-PAF, age 65 years), who underwent EAVM during AF prior to PVI, were divided into 2 groups according to the presence or absence of LVA outside the PV antra, defined as bipolar voltage of <0.5 mV. LVA-guided substrate modification was performed after PVI in patients with LVA. LVA was found in 159 patients (79%). Non-PAF (OR 3.851, P = 0.002) and CHA2 DS2 -VASc score (OR 1.815, P < 0.001) were independent predictors for the LVA. After the index procedure, 144 patients (72%) were free from AF at 12 months. With multiple procedures, 148 patients (74%) during a median follow-up of 3.1 years were free from the recurrence. There was no difference in the recurrence (log-rank P = 0.746), and complications (0% vs. 7%, P = 0.125) between the groups. Neither LVA nor Non-PAF was an independent predictor for the recurrence in a multivariate analysis. CONCLUSIONS: Patients with LVA had an equally favorable long-term ablation outcome compared to those without. As an adjunct to PVI, voltage-guided substrate modification may be an important ablation strategy in patients with LA structural remodeling.

Correlation of Left Atrial Voltage Distribution Between Sinus Rhythm and Atrial Fibrillation: Identifying Structural Remodeling by 3-D Electroanatomic Mapping Irrespective of the Rhythm.

INTRODUCTION: Left atrial (LA) electroanatomical voltage mapping (EAVM) correlates with scar on LGE-MRI and has been used to guide ablation of low voltage area (LVA) in sinus rhythm (SR). We compared EAVM in SR and AF in a cohort of AF patients, and in SR between patients with AF and without AF or structural heart disease (control). METHODS AND RESULTS: Twenty-seven AF patients, 9 with paroxysmal AF (PAF), underwent point-by-point EAVM during SR and AF using same Carto3 geometry. Only adjacent SR-AF points (≤ 5 mm apart) were compared. In addition, 6 control patients were evaluated. There was a linear bipolar voltage correlation between SR and AF (r = 0.707, P < 0.001, Y = 1.515X + 0.786). LA bipolar voltage in patients with PAF was higher than those with Non-PAF in SR (2.24 ± 1.51 vs. 1.56 ± 1.53 mV) and AF (0.81 ± 0.60 vs. 0.58 ± 0.62 mV, both for P < 0.001). The pulmonary vein antra voltage was significantly lower than other LA regions in PAF (1.28 ± 0.79 vs. 2.54 ± 1.50 mV, P < 0.001) and Non-PAF patients (1.13 ± 1.04 vs. 1.86 ± 1.72 mV, P < 0.001), while no voltage differences was found in the control group (P = 0.998). CONCLUSION: There was a linear voltage correlation between SR and AF, suggesting a similar extent of LA fibrotic substrate can be identified on EAVM by adjusting the voltage cutoff. Structural remodeling starts in the PV antra and may progress to other LA regions.