Abstract 18815: Spectral CT Study to Evaluate Left Atrial Remodeling Using Anatomic and Electron Density Numbers in Patients Scheduled to Undergo Pulmonary Vein Isolation

Abstract

Introduction: Left atrial (LA) wall remodeling, such as fibrosis and inflammation, may occur in patients with atrial fibrillation (AF) to cause a low voltage AF wave and thickened LA wall. To date, an invasive biopsy has been used to evaluate LA wall remodeling. Hypothesis: Using novel spectral CT with an effective atomic number (EAN) and electron density number (EDN), which are new parameters in addition to CT attenuation, LA anterior wall characteristics can be evaluated. Methods: A total of 13 patients (eight males, mean age 69 years) scheduled for pulmonary vein isolation (PVI) underwent cardiac spectral CT (7500, Philips, Tokyo, Japan). This revealed AF in four patients and a sinus rhythm in nine. From non-contrast, and early and late phase contrast data, EAN and EDN (%EDV) of the LA anterior wall were determined. Results: Mean EANs for the LA anterior wall were 7.35 in patients with AF, and 7.38 in patients with a sinus rhythm, respectively (P=NS), during the non-contrast phase; 8.18 and 8.17, respectively (P=NS), during the early phase; and 8.59 and 8.51, respectively (P=NS) during the late phase. Mean EDNs (%EDW) were 102.7 in patients with AF, and 103,1 in patients with a sinus rhythm, respectively (P=NS) during the non-contrast phase; 102,6 and 103.4, respectively (P=NS) during the early phase; and 103.7 and 103.5, respectively (P=NS) during the late phase. In patients with AF, both LA anterior thickness on CT and LA volume determined by transthoracic echocardiogram had a significant negative correlation with the voltage of AF waves (V2 lead) (R= -0.87 and -0.46, respectively). The EDN, but not EAN, in non-contrast, and early and late phases after contrast material showed a significant negative correlation with the voltage of AF waves (R= -0.74, -0.75, respectively). Conclusions: This is the first study in which characteristics of the LA anterior wall were evaluated by EAN and EDN on spectral CT. As well as LA anterior wall thickening and an enlarged LA volume, the EDN was an indicator of characteristic changes of the LA anterior wall that related to the low voltage of AF waves. This new parameter determined by spectral CT may evaluate characteristics of the LA anterior wall and be a predictor of future occurrence of LA remodeling that is related to the effectiveness of PVI.