Cardiovascular Magnetic Resonance Imaging of Scar Development Following Pulmonary Vein Isolation: A Prospective Study

Abstract

AimsCardiovascular magnetic resonance (MR) provides non-invasive assessment of early (24-hour) edema and injury following pulmonary vein isolation (by ablation) and subsequent scar formation. We hypothesize that 24-hours after ablation, cardiovascular MR would demonstrate a pattern of edema and injury due to ablation and the severity would correlate with subsequent scar.MethodsFifteen atrial fibrillation patients underwent cardiovascular MR prior to pulmonary vein isolation, 24-hours post (N = 11) and 30-days post (N = 7) ablation, with T2-weighted (T2W) and late gadolinium enhancement (LGE) imaging. Left atrial wall thickness, edema enhancement ratio and LGE enhancement were assessed at each time point. Volumes of LGE and edema enhancement were measured, and the circumferential presence of injury was assessed at 24-hours, including comparison with LGE enhancement at 30 days.ResultsLeft atrial wall thickness was increased 24-hours post-ablation (10.7±4.1 mm vs. 7.0±1.8 mm pre-PVI, p<0.05). T2W enhancement at 24-hours showed increased edema enhancement ratio (1.5±0.4 for post-ablation, vs. 0.9±0.2 pre-ablation, p<0.001). Edema and LGE volumes at 24-hours were correlated with 30-day LGE volume (R = 0.76, p = 0.04, and R = 0.74, p = 0.09, respectively). Using a 16 segment model for assessment, 24-hour T2W had sensitivity, specificity, and accuracy of 82%, 63%, and 79% respectively, for predicting 30-day LGE. 24-hour LGE had sensitivity, specificity, and accuracy of 91%, 47%, and 84%.ConclusionsIncreased left atrial wall thickening and edema were characterized on cardiovascular MR early post-ablation, and found to correlate with 30-day LGE scar.

Black blood myocardialT2mapping

“…Inflammation or edema could also occur in the thin wall of the left atrium (LA) or right ventricle (RV). For example, radio-frequency ablation for treatment of atrial fibrillation causes LA edema, which can be detected with T 2 weighted imaging (44–46); however T 2 weighted imaging in LA or RV is challenging and interpretation is subjective. Conventional bright blood T 2 maps do not allow accurate measurement of LA T 2 due to partial voluming.…”

Case report: Cardiac arrest after radiofrequency ablation in a 76-year-old male

“…Previous studies have shown that myocardial edema can occur within 1 day after radiofrequency ablation. [1][2][3][4][5][6][7] The degree of edema depends on the intensity and quantity of radiofrequency energy during pulmonary vein ablation. [8] The fluid is usually absorbed in about 1 to 3 months, [3,9,10] and the speed of resorption is closely related to early recurrence of AF, [11] which may be due to changes in conductance and transmembrane ion currents soon after ablation or to cardiomyocyte edema.…”

The Role of the Left Atrium: From Multimodality Imaging to Clinical Practice: A Review

“…CMR LGE could have a significant role also during the postablation phase. LA wall thickening and oedema following pulmonary vein ablation correlate with a 30-day LGE scar [ 81 ]. Atrial regions ablated show a higher contrast uptake and thinner myocardium, compared with regions with pre-existing LGE.…”