Intra-Atrial Dyssynchrony Using Cardiac Magnetic Resonance to Quantify Tissue Remodeling in Patients with Atrial Fibrillation

Abstract Background: Recent studies suggest that left atrial (LA) late gadolinium enhancement (LGE) can quantify the underlying tissue remodeling that harbors atrial fibrillation (AF). However, quantification of LA-LGE requires labor-intensive magnetic resonance imaging acquisition and postprocessing at experienced centers. LA intra-atrial dyssynchrony assessment is an emerging imaging technique that predicts AF recurrence after catheter ablation. We hypothesized that 1) LA intra-atrial dyssynchrony is associated with LA-LGE in patients with AF and 2) LA intra-atrial dyssynchrony is greater in patients with persistent AF than in those with paroxysmal AF. Method: We conducted a cross-sectional study comparing LA intra-atrial dyssynchrony and LA-LGE in 146 patients with a history of AF (60.0 ± 10.0 years, 30.1% nonparoxysmal AF) who underwent pre-AF ablation cardiac magnetic resonance (CMR) in sinus rhythm. Using tissue-tracking CMR, we measured the LA longitudinal strain in two- and four-chamber views. We defined intra-atrial dyssynchrony as the standard deviation (SD) of the time to peak longitudinal strain (SD-TPS, in %) and the SD of the time to the peak pre-atrial contraction strain corrected by the cycle length (SD-TPSpreA, in %). We used the image intensity ratio (IIR) to quantify LA-LGE. Results: Intra-atrial dyssynchrony analysis took 5 ± 9 minutes per case. Multivariable analysis showed that LA intra-atrial dyssynchrony was independently associated with LA-LGE. In addition, LA intra-atrial dyssynchrony was significantly greater in patients with persistent AF than those with paroxysmal AF. In contrast, there was no significant difference in LA-LGE between patients with persistent and paroxysmal AF. LA intra-atrial dyssynchrony showed excellent reproducibility and its analysis was less time-consuming (5 ± 9 minutes) than the LA-LGE (60 ± 20 minutes). Conclusion: LA Intra-atrial dyssynchrony is a quick and reproducible index that is independently associated with LA-LGE to reflect the underlying tissue remodeling

Association between interatrial block, left atrial fibrosis, and mechanical dyssynchrony: Electrocardiography‐magnetic resonance imaging correlation

Introduction Advanced interatrial block (IAB) on a 12‐lead electrocardiogram (ECG) is a predictor of stroke, incident atrial fibrillation (AF), and AF recurrence after catheter ablation. The objective of this study was to determine which features of IAB structural remodeling is associated with left atrium (LA) magnetic resonance imaging structure and function. Methods/Results We included 152 consecutive patients (23% nonparoxysmal AF) who underwent preprocedural ECG and cardiac magnetic resonance (CMR) in sinus rhythm before catheter ablation of AF. IAB was defined as P‐wave duration ≥120 ms, and was considered partial if P‐wave was positive and advanced if P‐wave had a biphasic morphology in inferior leads. From cine CMR and late gadolinium enhancement, we derived LA maximum and minimum volume indices, strain, LA fibrosis, and LA dyssynchrony. A total of 77 patients (50.7% paroxysmal) had normal P‐wave, 52 (34.2%) partial IAB, and 23 (15.1%) advanced IAB. Patients with advanced IAB had significantly higher LA minimum volume index (25.7 vs 19.9 mL/m2, P = .010), more LA fibrosis (21.9% vs 13.1%, P = .020), and lower LA maximum strain rate (0.99 vs 1.18, P = .007) than those without. Advanced IAB was independently associated with LA (minimum [P = .032] and fibrosis [P = .009]). P‐wave duration was also independently associated with LA fibrosis (β = .33; P = .049) and LA mechanical dyssynchrony (β = 2.01; P = .007). Conclusion Advanced IAB is associated with larger LA volumes, lower emptying fraction, and more fibrosis. Longer P‐wave duration is also associated with more LA fibrosis and higher LA mechanical dyssynchrony.Sin financiación2.871 JCR (2020) Q3, 79/142 Cardiac & Cardiovascular Systems1.193 SJR (2020) Q1, 72/349 Cardiology and Cardiovascular MedicineNo data IDR 2020UE

Ablation as targeted perturbation to rewire communication network of persistent atrial fibrillation

<div><p>Persistent atrial fibrillation (AF) can be viewed as disintegrated patterns of information transmission by action potential across the communication network consisting of nodes linked by functional connectivity. To test the hypothesis that ablation of persistent AF is associated with improvement in both local and global connectivity within the communication networks, we analyzed multi-electrode basket catheter electrograms of 22 consecutive patients (63.5 ± 9.7 years, 78% male) during persistent AF before and after the focal impulse and rotor modulation-guided ablation. Eight patients (36%) developed recurrence within 6 months after ablation. We defined communication networks of AF by nodes (cardiac tissue adjacent to each electrode) and edges (mutual information between pairs of nodes). To evaluate patient-specific parameters of communication, thresholds of mutual information were applied to preserve 10% to 30% of the strongest edges. There was no significant difference in network parameters between both atria at baseline. Ablation effectively rewired the communication network of persistent AF to improve the overall connectivity. In addition, successful ablation improved local connectivity by increasing the average clustering coefficient, and also improved global connectivity by decreasing the characteristic path length. As a result, successful ablation improved the efficiency and robustness of the communication network by increasing the small-world index. These changes were not observed in patients with AF recurrence. Furthermore, a significant increase in the small-world index after ablation was associated with synchronization of the rhythm by acute AF termination. In conclusion, successful ablation rewires communication networks during persistent AF, making it more robust, efficient, and easier to synchronize. Quantitative analysis of communication networks provides not only a mechanistic insight that AF may be sustained by spatially localized sources and global connectivity, but also patient-specific metrics that could serve as a valid endpoint for therapeutic interventions.</p></div

Patient enrollment.

<p>EGM, electrogram.</p

Communication network analysis.

<p><b><i>A</i></b>. <i>Structural network of basket catheter</i>. Edges (red line) indicate physical connectivity between the nodes (blue spheres; cardiac tissues adjacent to the electrodes). <b><i>B</i></b>. <i>Representative average all-to-all mutual information matrix (64 x 64) of 5 consecutive 10-second time windows within the left atrium before ablation</i>. The <i>x</i>- and <i>y</i>-axes indicate individual electrodes of the basket catheter. The value of mutual information between two electrodes is color-coded and expressed in <i>nats</i>, the natural unit of information. The diagonal components from the upper left to the lower right are intentionally set to zero to exclude self-edges. <b><i>C</i></b>. <i>Representative distribution of edges rank-ordered by mutual information</i>. In the absence of self-edges, there are 2,016 undirected edges between each pair of 64 electrodes (= [64 x 64–64]/2). To evaluate patient-specific parameters of communication, thresholds of mutual information are applied to set the connection density between 0.1 and 0.3, which preserves 10% to 30% of the strongest edges [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0179459#pone.0179459.ref030" target="_blank">30</a>]. Blue, right atrium; red, left atrium. <b><i>D</i></b>. <i>Binary adjacency matrix</i>. The top panel indicates a matrix with connection density 0.3 (threshold = 0.1704); the bottom panel indicates a matrix with connection density 0.1 (threshold = 0.2834). If the element (<i>i</i>, <i>j</i>) is one (white), an edge between electrode <i>i</i> and <i>j</i> is said to exist; otherwise (black), it does not exist. <b><i>E</i></b>. <i>Communication network</i>. Edges (red line) indicate functional connectivity with suprathreshold mutual information between the nodes (blue spheres; cardiac tissues adjacent to the electrodes). The top panel indicates a communication network with connection density 0.3; the bottom panel indicates a communication network with connection density 0.1.</p

Patient demographics.

<p>Data are presented as mean ± standard deviation or n (%). P-value was calculated between patients with recurrence and no recurrence using Pearson's <i>χ</i>² test for categorical variables and Student’s <i>t</i>-tests for continuous variables. AF, atrial fibrillation; CHA₂DS₂-VASc, combined stroke risk score: Cardiac failure, Hypertension, Age ≥65 or 75 years, Diabetes, prior Stroke/ transient ischemic attack (TIA), VAscular disease, Sex category; LA, left atrial; LV, left ventricular.</p

Ablation sites guided by the focal impulse and rotor modulation mapping system.

<p>Blue circles indicate ablation sites. SVC, superior vena cava; IVC, inferior vena cava; RAA, right atrial appendage; LAA, left atrial appendage; RSPV, right superior pulmonary vein; LSPV, left superior pulmonary vein; RIPV, right inferior pulmonary vein; LIPV, left inferior pulmonary vein.</p