Left atrial voltage mapping using a new impedance-based algorithm in patients with paroxysmal atrial fibrillation

Association of beat-to-beat P-wave analysis index to the extent of left atrial low-voltage areas in patients with paroxysmal atrial fibrillation

BACKGROUND

Left atrial (LA) fibrosis has been shown to be associated with atrial fibrillation (AF) recurrence. Beat-to-beat (B2B) index is a non-invasive classifier, based on B2B P-wave morphological and wavelet analysis, shown to be associated with AF incidence and recurrence. In this study, we tested the hypothesis that the B2B index is associated with the extent of LA low-voltage areas (LVAs) on electroanatomical mapping.

METHODS

Patients with paroxysmal AF scheduled for pulmonary vein isolation, without evident structural remodeling, were included. Pre-ablation electroanatomical voltage maps were used to calculate the surface of LVAs (<0.5 mV). B2B index was compared between patients with small versus large LVAs.

RESULTS

35 patients were included (87% male, median age 62). The median surface area of LVAs was 7.7 (4.4-15.8) cm2 corresponding to 5.6 (3.3-12.1) % of LA endocardial surface. B2B index was 0.57 (0.52-0.59) in patients with small LVAs (below the median) compared to 0.65 (0.56-0.77) in those with large LVAs (above the median) (p = 0.009). In the receiver operator characteristic curve analysis for predicting large LVAs, the c-statistic was 0.75 (p = 0.006) for B2B index and 0.81 for the multivariable model including B2B index (multivariable p = 0.04) and P-wave duration.

CONCLUSION

In patients with paroxysmal AF without overt atrial myopathy, B2B P-wave analysis appears to be a useful non-invasive correlate of low-voltage areas-and thus fibrosis-in the LA. This finding establishes a pathophysiological basis for B2B index and its potential usefulness in the selection process of patients who are likely to benefit most from further invasive treatment.

Characterization of arrhythmia substrate to ablate persistent atrial fibrillation (COAST-AF): Randomized controlled trial design and rationale

BACKGROUND

Atrial low voltage area (LVA) catheter ablation has emerged as a promising strategy for ablation of persistent atrial fibrillation (AF). It is unclear if catheter ablation of atrial LVA increases treatment success rates in patients with persistent AF.

OBJECTIVE

The primary aim of this trial is to assess the potential benefit of adjunctive catheter ablation of atrial LVA in addition to pulmonary vein isolation (PVI) in patients with persistent AF, when compared to PVI alone. The secondary aims are to evaluate safety outcomes, the quality of life and the healthcare resource utilization.

METHODS/DESIGN

A multicenter, prospective, parallel-group, 2-arm, single-blinded randomized controlled trial is under way (NCT03347227). Patients who are candidates for catheter ablation for persistent AF will be randomly assigned (1:1) to either PVI alone or PVI + atrial LVA ablation. The primary outcome is 18-month documented event rate of atrial arrhythmia (AF, atrial tachycardia or atrial flutter) post catheter ablation. Secondary outcomes include procedure-related complications, freedom from atrial arrhythmia at 12 months, AF burden, need for emergency department visits/hospitalization, need for repeat ablation for atrial arrhythmia, quality of life at 12 and 18 months, ablation time, and procedure duration.

DISCUSSION

Characterization of Arrhythmia Mechanism to Ablate Atrial Fibrillation (COAST-AF) is a multicenter randomized trial evaluating ablation strategies for catheter ablation. We hypothesize that catheter ablation of atrial LVA in addition to PVI will result in higher procedural success rates when compared to PVI alone in patients with persistent AF.

Discrepancy between CARTO and Rhythmia maps for defining the left atrial low-voltage areas in atrial fibrillation ablation

Reported mapping procedures of left atrial (LA) low-voltage areas (LVAs) vary widely. This study aimed to compare the PentaRay^®/CARTO^®3 (PentaRay map) and Orion™/Rhythmia™ (Orion map) systems for LA voltage mapping. This study included 15 patients who underwent successful pulmonary vein isolation (PVI) for atrial fibrillation. After PVI, PentaRay and Orion maps created for all patients were compared. LVAs were defined as sites with ≥ 3 adjacent low-voltage points < 0.5 mV. LVAs were indicated in 8 (53%) among 15 patients, and the average values of the measured LVAs was comparable between the systems (PentaRay map = 5.4 ± 8.7 cm²; Orion map = 4.3 ± 6.4 cm², p = 0.69). However, in 2 of 8 patients with LVAs, the Orion map indicated LVAs at the septum and posterolateral sites of the LA, respectively, whereas the PentaRay map indicated no LVAs. In those patients, sharp electrograms of > 0.5 mV were properly recorded at the septum and posterolateral sites during appropriate beats in the PentaRay map. The PentaRay map had a shorter procedure time than the Orion map (12 ± 3 min vs. 23 ± 8 min, respectively; p < 0.01). Our study results showed a discrepancy in the LVA evaluation between the PentaRay and Orion maps. In 2 of 15 patients, the Orion map indicated LVAs at the sites where > 0.5-mV electrograms were properly recorded in the PentaRay map.

The coronary artery calcium score correlates with left atrial low-voltage area: Sex differences

INTRODUCTION

In patients with coronary artery disease, a high coronary artery calcium score (CACS) correlates with atrial fibrillation (AF); however, the association between left atrial (LA) remodeling progression and coronary arteriosclerosis is unclear. This study aimed to evaluate the relationship between LA remodeling progression and the CACS.

METHODS

This retrospective study enrolled 148 patients with AF (paroxysmal AF, n = 94) who underwent catheter ablation. Voltage mapping for the left atrium and coronary computed tomography for CACS calculations were performed. The ratio of the LA low-voltage area (LA-LVA), defined by values less than 0.5 mV divided by the total LA surface without pulmonary veins, was calculated. Patients with LA-LVA (<0.5 mV) >5% and ≤5% were classified as the LVA (n = 30) and non-LVA (n = 118) groups, respectively. Patient characteristics and CACS values were compared between the two groups.

RESULTS

LA volume, age, CHA₂ DS₂ VASc score, and percentage of female patients were significantly higher, and the estimated glomerular filtration rate was lower in the LVA group than in the non-LVA group. The CACS was significantly higher in the LVA group (248.4 vs. 13.2; p = .001). Multivariate analysis identified the LA volume index and CACS as independent predictors of LA-LVA (<0.5 mV) greater than 5%. The areas under the receiver operating characteristic curves for predicting LA-LVA (<0.5 mV) greater than 5% with CACS were 0.695 in the entire population, 0.782 in men, and 0.587 in women.

CONCLUSION

Progression of LA remodeling and coronary artery calcification may occur in parallel. A high CACS may indicate advanced LA remodeling, especially in men.

Catheter Ablation of Low-Voltage Areas for Persistent Atrial Fibrillation: Procedural Outcomes Using High-Density Voltage Mapping

BACKGROUND

Several approaches have been proposed to address the challenge of catheter ablation of persistent atrial fibrillation (AF). However, the optimal ablation strategy is unknown. We sought to evaluate the efficacy of pulmonary vein isolation (PVI) plus low-voltage area (LVA) ablation using contemporary high-density mapping to identify LVA in patients with persistent AF.

METHODS

Consecutive patients accepted for AF catheter ablation were studied. High-density bipolar voltage mapping data were acquired in sinus rhythm using multipolar catheters to detect LVA (defined as bipolar voltage < 0.5 mV). Semiautomated impedance-based software was used to ensure catheter contact during data collection. Patients underwent PVI + LVA ablation (if LVA present).

RESULTS

A total of 145 patients were studied; 95 patients undergoing PVI + LVA ablation were compared with 50 controls treated with PVI only. Average age was 61 ± 10 years, and 80% were male. Baseline characteristics were comparable. Freedom from atrial tachycardia/AF at 18 months was 72% after PVI + LVA ablation vs 58% in controls (P = 0.022). Median procedure duration (273 [240, 342] vs 305 [262, 360] minutes; P = 0.019) and radiofrequency delivery (50 [43, 63] vs 55 [35, 68] minutes; P = 0.39) were longer in the PVI + LVA ablation group. Multivariable analysis showed that the ablation strategy (PVI + LVA) was the only independent predictor of freedom from atrial tachycardia/AF (hazard ratio, 0.53; 95% confidence interval, 0.29-0.96; P = 0.036). There were no adverse safety outcomes associated with LVA ablation.

CONCLUSIONS

An individualized strategy of high-density mapping to assess the atrial substrate followed by PVI combined with LVA ablation is associated with improved outcomes. Adequately powered randomized clinical trials are needed to determine the role of PVI + LVA ablation for persistent AF.

Atrial Fibrosis: Translational Considerations for the Management of AF Patients

Fibrosis plays a fundamental role in the initiation and maintenance of AF, mainly due to enhanced automaticity and anisotropy-related re-entry. The identification and quantification of atrial fibrosis is achieved either preprocedurally by late gadolinium enhancement MRI or intraprocedurally using electroanatomic voltage mapping. The presence and extent of left atrial fibrosis among AF patients may influence relevant decision making regarding the need for anticoagulation, the adoption of rate versus rhythm control and mainly the type of ablation strategy that will be followed during interventional treatment. Several types of individualised substrate modifications targeting atrial fibrotic areas have been proposed, although their impact on patient outcome needs to be further investigated in adequately powered prospective randomised controlled clinical trials.