Left Atrial Remodeling Identification and Catheter Ablation Outcomes With ¹⁸ F‐Fluorodeoxyglucose Positron Emission Tomography in Persistent Atrial Fibrillation

Figures

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  Figure 1. Workflow of the acquisition, alignment, segmentation, and postprocessing of left atrial CMRI LGE, left atrial EAVM and left atrial 18F‐FDG‐PET images. A, Images were acquired during AF before the ablation procedure (CMR—18F‐FDG) and were at first visually aligned with CMR angiographic images. B, The segmentations of the LA in DE‐CMR and PET were reformated as 3D models. C, A maximum‐intensity projection of the values inside the atrial wall was used to overlay the models. D, All models, including the EAVM, were then coregistered with a 3D model reconstructed from magnetic resonance angiography, using an iterative closest point algorithm (12 degrees of freedom, including deformation and scaling). This allows direct comparison by visual inspection. E, LGE fibrosis extent (CMR), LVA extent (EAVM), and LGU extent (18F‐FDG PET) were identified and quantified after excluding the mitral valve and pulmonary vein volumes. 18F‐FDG indicates 18F‐fluorodeoxyglucose; 3D, 3‐dimensional; AF, atrial fibrillation; CT, computed tomography; DE, delayed enhancement; EAVM electroanatomical voltage mapping; LA, left atrium; LGE CMR, late gadolinium enhancement cardiac magnetic resonance; LGU, low…

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  Figure 2. Segmented 3D 18F‐FDG uptake map relationship with 3D EAVM acquired during AF ablation procedure in PA and AP views. The color gradient of the LVA maps indicates endocardial electrogram amplitude from pink (>0.3 mV in AF) to red (at <0.1 mV). The color gradient of the LGU maps indicates 18F‐FDG standardized uptake value amplitude from dark/brown (LGU area) to yellow (without LGU area). A, Illustration of a patient showing a homogenous distribution of the tracer without LGU extent in the LA wall. Color 3D EAVM shows electrically normal atrial tissue without LVA. B, Illustration of a LA with moderate remodeling, displaying a heterogeneous tracer distribution indicating LGU area in the posterior and inferior segments of the LA, particularly around the left inferior PV and right inferior PV ostia. LGU is also evident in the anteroseptal region of the LA. Color 3D EAVM in the PA and AP views show abnormal atrial tissue with LVA in the corresponding region. C, Illustration of a LA with extensive remodeling. Heterogeneity of the tracer distribution is more pronounced with significant LGU in the LA's posteroinferior, anterior, and anteroseptal regions, corresponding on EAVM to abnormal…

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  Figure 3. Correlation between the different imaging modalities evaluated through linear regression analysis and the Pearson correlation coefficient. A, Correlation between LGU extent (with 18F‐FDG‐PET) and LVA extent (with EAVM). B, Correlation between LA mean SUV (with 18F‐FDG‐PET) and VGLA (with EAVM). LA indicates left atrium; LGU, low glucose uptake; LVA, low voltage area with electroanatomical voltage map acquired in atrial fibrillation; SUV, standardized uptake value; and VGLA, global left atrial voltage acquired in atrial fibrillation.

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  Figure 4. Illustration of the LA segmentation with PA and AP view. The posterior segment is marked in blue, the inferior in green and the anterior in orange. The result of the correlation between LGU and LVA evaluated through linear regression analysis and the Pearson correlation coefficient are reported in the corresponding segments. AP indicates anteroposterior view; LA, left atrium; LGU, low glucose uptake; LVA, low voltage area with electroanatomical voltage map acquired during atrial fibrillation; and PA, posteroanterior view.

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  Figure 5. Receiver‐operating characteristic curve analysis for prediction of moderate or extensive LVA during EAVM. AUC indicates area under the curve; EAVM, electroanatomical voltage mapping; LAVI, left atrium volume index; LGE, extent fibrosis detected with late gadolinium enhancement cardiac magnetic resonance imaging; LGU, low glucose uptake; and LVA, low voltage area.

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  Figure 6. Receiver‐operating characteristic curve analysis for prediction of atrial fibrillation recurrence after catheter ablation. AUC indicates area under the curve; LAVI, left atrium volume index; LGE extent, fibrosis detected with late gadolinium enhancement cardiac magnetic resonance imaging; LGU, low glucose uptake; LVA, low voltage area; and VGLA, global left atrial voltage acquired in atrial fibrillation.

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  Figure 7. Kaplan–Meier estimates of freedom from documented atrial fibrillation more than 30 seconds after AF ablation procedure according to LGU extent, with or without the use of antiarrhythmic medications. AF indicates atrial fibrillation; and LGU, low glucose uptake.

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  Figure 8. Schematic diagram of FDG uptake interpretation. A (blue), illustration of patient in SR with normal LA wall 18F‐FDG uptake in PA views. B (green), patient during AF without structural remodeling and showing homogenous distribution of the tracer with increased LA wall 18F‐FDG uptake. C (yellow), patient during AF with structural remodeling and showing heterogenous distribution of the tracer with variable magnitude of LA wall 18F‐FDG uptake. After administration of a nicotinic acid derivative (acipimox), compared with SR, the LA behaves similarly to the hibernating LV, significantly enhancing atrial 18F‐FDG uptake during persistent AF (blue to green). In case of viable atrial myocytes 18F‐FDG uptake is thus increased. 21 In patients with LA structural remodeling (yellow), LA FDG‐PET 3D map illustration shows heterogeneous distribution of the tracer in the LA with low FDG uptake areas and variable magnitude of the global LA wall 18F‐FDG uptake. These areas of metabolic defects and LGU correlate to areas with low endocardial voltage area suggesting the replacement of myocytes by atrial fibrosis. 18F‐FDG indicates 18F‐fluorodeoxyglucose; 3D, 3‐dimensional; AF, atrial fibrillation;…