Characterization of Low-Voltage Areas in Patients With Atrial Fibrillation: Insights From High-Density Intracardiac Mapping

Early diagnosis and better rhythm management to improve outcomes in patients with atrial fibrillation: the 8th AFNET/EHRA consensus conference

Despite marked progress in the management of atrial fibrillation (AF), detecting AF remains difficult and AF-related complications cause unacceptable morbidity and mortality even on optimal current therapy. This document summarizes the key outcomes of the 8th AFNET/EHRA Consensus Conference of the Atrial Fibrillation NETwork (AFNET) and the European Heart Rhythm Association (EHRA). Eighty-three international experts met in Hamburg for 2 days in October 2021. Results of the interdisciplinary, hybrid discussions in breakout groups and the plenary based on recently published and unpublished observations are summarized in this consensus paper to support improved care for patients with AF by guiding prevention, individualized management, and research strategies. The main outcomes are (i) new evidence supports a simple, scalable, and pragmatic population-based AF screening pathway; (ii) rhythm management is evolving from therapy aimed at improving symptoms to an integrated domain in the prevention of AF-related outcomes, especially in patients with recently diagnosed AF; (iii) improved characterization of atrial cardiomyopathy may help to identify patients in need for therapy; (iv) standardized assessment of cognitive function in patients with AF could lead to improvement in patient outcomes; and (v) artificial intelligence (AI) can support all of the above aims, but requires advanced interdisciplinary knowledge and collaboration as well as a better medico-legal framework. Implementation of new evidence-based approaches to AF screening and rhythm management can improve outcomes in patients with AF. Additional benefits are possible with further efforts to identify and target atrial cardiomyopathy and cognitive impairment, which can be facilitated by AI.

P wave duration ≥150 ms predicts poor left atrial function and ablation outcomes in non-paroxysmal atrial fibrillation

BACKGROUND

It remains unknown whether P wave duration (PWD) ≥ 150 ms measured after extensive radiofrequency catheter ablation (RFCA) can identify non-paroxysmal atrial fibrillation (non-PAF) patients at increased risk of atrial tachyarrhythmia recurrence. We investigated the predicting power of PWD and its association with left atrial (LA) reverse remodeling in patients with non-PAF undergoing pulmonary vein isolation with LA linear ablation.

METHODS

We retrospectively evaluated 136 patients who underwent RFCA for drug-refractory non-PAF. Electroanatomic mapping was acquired during AF. Low-voltage area (LVA) was defined as an area with bipolar voltage ≤0.5 mV. Electrocardiography and echocardiography were performed during sinus rhythm 1 day and 3 months after RFCA. PWD was measured using amplified 12‑lead electrocardiography. Prolonged PWD was defined as maximum PWD ≥ 150 ms.

RESULTS

Over a mean follow-up duration of 48 ± 35 months, 28 patients experienced atrial tachyarrhythmia recurrence. PWD was positively correlated with LVA (r = 0.527, p < 0.001) and inversely correlated with LA emptying fraction (r = -0.399, p < 0.001). PWD was shortened and LA emptying fraction (LAEF) was increased in patients without atrial tachyarrhythmia recurrence during follow-up. Atrial tachyarrhythmia-free survival was significantly more likely in patients without a prolonged PWD (83.5% vs 60.7%, p = 0.002). Multivariate analysis showed that LAEF and PWD were independent predictors of atrial tachyarrhythmia recurrence.

CONCLUSIONS

PWD ≥ 150 ms measured after RFCA can identify patients with non-PAF at increased risk of atrial tachyarrhythmia recurrence. PWD is correlated with LVA and LAEF and reflects LA reverse remodeling.

Retrospective analysis of FIRM-guided ablation in patients with recurrent atrial fibrillation: a single-center study

BACKGROUND

Ablation of recurrent atrial fibrillation (AF) is common. Studies indicate that AF recurrence is primarily due to pulmonary vein (PV) re-conduction. This retrospective analysis characterized and evaluated recurrent AF patients using focal impulse and rotor mapping (FIRM) plus PV re-isolation, with follow up at 3, 6, 12, and 24 months after the repeat ablation.

METHODS AND RESULTS

Patients (consecutive, n = 100) underwent FIRM-guided ablation followed by conventional PV re-isolation for recurrent AF treatment. All FIRM patients had failed one or more conventional ablation procedures (1.4 ± 0.08) for paroxysmal (14%), persistent (15%), and long-standing persistent (71%) AF. Stable rotors were identified in 97/100 patients: 60% in the right atrium (RA) and 82% in left atrium (LA) (mean 1.5 ± 0.8 and 2.1 ± 1.2 per patient, respectively). No correlation was noted between the previous number of ablations, AF duration, or LA diameter to the number of rotors (R² = 0.0039, R² = 0.0017, and R² = 0.006, respectively). In this limited observation, only 22% of identified rotors were associated with proximity to low voltage areas. The 12- and 24-month arrhythmia free rate was 93% (13/14) and 92% (12/13) for paroxysmal AF, 60% (9/15) and 47% (7/15) for persistent AF, and 70% (48/69) and 64% (43/67) for long-standing persistent AF, respectively, after a single FIRM procedure and re-isolation of the veins.

CONCLUSIONS

The data show a benefit for FIRM-guided ablation in recurrent AF at 12 months. No correlation was found between rotors and tissue characterization, AF duration, or previous number of ablations, suggesting that rotors may play an independent role in maintaining recurrent AF after prior failed ablation.

Atrial Myopathy Underlying Atrial Fibrillation

While AF most often occurs in the setting of atrial disease, current assessment and treatment of patients with AF does not focus on the extent of the atrial myopathy that serves as the substrate for this arrhythmia. Atrial myopathy, in particular atrial fibrosis, may initiate a vicious cycle in which atrial myopathy leads to AF, which in turn leads to a worsening myopathy. Various techniques, including ECG, plasma biomarkers, electroanatomical voltage mapping, echocardiography, and cardiac MRI, can help to identify and quantify aspects of the atrial myopathy. Current therapies, such as catheter ablation, do not directly address the underlying atrial myopathy. There is emerging research showing that by targeting this myopathy we can help decrease the occurrence and burden of AF.

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.

Association between prolonged P wave duration and left atrial scarring in patients with paroxysmal atrial fibrillation

BACKGROUND

We evaluated the association of P wave duration (PWD) with left atrial scar (LAS) in patients with paroxysmal atrial fibrillation (PAF).

METHODS

Consecutive patients with PAF undergoing their first catheter ablation were screened and only those in sinus rhythm at baseline were included in the analysis. A standard 12-lead electrocardiogram (ECG) was performed in all and three-dimensional voltage mapping of the left atrium was generated for identification of low-voltage areas (≤0.2 mV) before the procedure.

RESULTS

In total, 411 patients with PAF were included in this study of which 181 had LASs (scar group), while 230 had no scar (nonscar group). In the scar group, patients were older (65.5 ± 8.8 vs 59.7 ± 11.7 years; P < .001), the proportion of female was higher (47.5% vs 37.4%; P = .04) and left atrial (LA) diameter (4.1 ± 0.6 vs 3.9 ± 0.6 cm; P < .001) was larger compared with the nonscar group. There was no significant difference in terms of hypertension, sleep apnea, and diabetes between the two groups. When comparing ECG characteristics between the two groups, PWD was significantly longer in the scar group (122.9 ± 18.5 and 116.9 ± 28.0 ms; P = .01). A multivariate analysis was performed, after adjustment of age, sex, LA diameter, PWD ≥ 120 ms was found to be an independent predictor of LA scarring (OR: 1.69, p-value: 0.02).

CONCLUSION

In the current series, prolonged PWD was found to be independently associated with LA scarring in PAF, even after adjustment for age, sex, and LA diameter.

The association between left atrial stiffness and low-voltage areas of left atrium in patients with atrial fibrillation

The low-voltage areas of left atrium (LA-LVA) have recently been of significant focus. However, very few studies have focused on the association between LA function and LA-LVA, and the mechanism of appearance of LA-LVA remains unclear. We investigated the marker for the existence of LA-LVA using automated 3-D mapping system. We studied 92 patients (75 males, 68 ± 9 years, 47 non-paroxysmal AF) who received CA for AF and 40 control patients without AF. Echocardiography was performed before the CA, and high-density voltage mapping during sinus rhythm after pulmonary isolation was performed in AF patients. LA-LVA was defined as < 0.5 mV, and LA stiffness index (LASI) was defined as the ratio of E/e' to LA peak strain. LA-LVA (LVA burden > 10%) was detected in 19/92 AF patients (21%). Patients with LA-LVA were associated with higher LASI (1.64 ± 1.70 vs. 0.61 ± 0.46, p < 0.0001), larger LA volume, non-paroxysmal AF, higher brain natriuretic peptide, structural heart disease, and older age. On multivariate analysis, LASI, LA volume, and age were independently associated with the existence of LA-LVA. Of these markers, the highest area under curve was obtained with LASI. The rate of high LASI (≥ 0.552) was highest in AF patients with LA-LVA. Moreover, the existence of LVA in anterior LA wall was associated with higher LASI. High LA stiffness index was associated with the presence of LA-LVA. The LA-LVA might be attributed to LA functional remodeling rather than LA anatomical remodeling.