Relation between left atrial wall composition by late gadolinium enhancement and complex fractionated atrial electrograms in patients with persistent atrial fibrillation: influence of non-fibrotic substrate in the left atrium

Abstract

The complex fractioned atrial electrogram (CFAE) has been considered as the catheter ablation target of left atrium (LA) under persistent atrial fibrillation (PeAF). We evaluated the relation between the LA wall composition by late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) and the CFAE in patients with PeAF. Forty-three patients underwent LGE-CMR and CFAE mapping before catheter ablation for PeAF. The LA wall substrates were classified into three: the fibrotic, intermediate, and normal substrates by using two thresholds of 2 standard deviation (2-SD) and 6-SD above the mean signal from the normal myocardium. For each of 12 preselected LA wall regions, the composition ratios (CRs) of fibrotic, indeterminate, and normal substrates were calculated as a percentage to the volume of LA wall region, and compared depending on the CFAE, respectively. The CR of normal substrate was significantly greater at the LA wall region with CFAE (52 ± 38% vs. 20 ± 28%, P < 0.01) than without CFAE. In contrast, the LA wall region with CFAE showed significantly lower CRs of intermediate substrate (39 ± 34% vs. 57 ± 31%, P < 0.01) and fibrotic substrate (7 ± 17% vs. 21 ± 24%, P < 0.01) than did the LA wall region without CFAE, respectively. Thus, the high CR (>18%) of normal substrate predicted the CFAE at the corresponding LA wall region with 71% sensitivity and 62% specificity. In conclusion, the evaluation of LA wall normal substrate by LGE-CMR might be useful to predict the CFAE occurrence before catheter ablation of PeAF.

Left Atrial Fibrosis Assessed with Cardiac MRI in Patients with Paroxysmal and Those with Persistent Atrial Fibrillation

“…Multivariable analysis showed that LA LGE in the LIPV antrum, two or more segments of the LA with LGE, and LAV more than 112 mL were independently associated with PAF. The spatial resolution of LGE MRI, with its thin section thickness of 1-2 mm, allows noninvasive evaluation of LA wall tissue characteristics (20,21). The assessment of ablation-induced LA wall injury by using LGE MRI is possible because of the wall thickening as well as the contrast enhancement (22).…”

Optimal Cardiac Magnetic Resonance Contrast-Enhanced Timing Robust Angiography (CMR-CENTRA) for the Three-Dimensional Reconstruction of the Bilateral Atria in the Electroanatomic Mapping (EAM) of Atrial Fibrillation

“…Paradoxically, ECG-gating CMR imaging during an arrhythmic attack may increase the image acquisition time and lead to adverse effects on the image quality (20). Third, CMR imaging allows the comprehensive evaluation of cardiac hemodynamics and tissue characteristics to enhance the understanding of AF (6,21). As CMR techniques advance, CMR imaging has been widely accepted as the effective pre-procedural imaging tool in the electroanatomic mapping of AF.…”

“…Usually, the AF arrhythmogenic substrates are in various heart structures such as the superior vena cava (SVC), inferior vena cava (IVC), coronary sinus (CS), pulmonary vein (PV), left atrium (LA), left atrial appendage (LAA), and right atrium (RA). Therefore, in the management of AF by a catheter ablation, suitable targets include the LA, LAA, RA and adjacent vessel structures (5,6).…”

Atrial Substrate Underlies the Recurrence after Catheter Ablation in Patients with Atrial Fibrillation

“…All cardiac MR LGE images were analyzed independently by two experienced radiologists (blinded to the patients’ clinical and electrophysiological data) at a commercial software workstation (Terarecon iNtuition; TeraRecon, Foster City, CA, USA). The 3D reconstruction process used to produce MR LGE images was as previously described [ 8 , 9 ]. On transverse or coronal MR LGE images, epicardial and endocardial borders of LA walls were semi-automatically contoured to select the entire LA walls and reconstruct 3D LA models.…”