Assessing Epicardial Substrate Using Intracardiac Echocardiography During VT Ablation

Abstract

Background Intracardiac echocardiography (ICE) has played a limited role in defining the substrate for ventricular tachycardia (VT). The purpose of this study was to assess whether ICE could identify abnormal epicardial substrate in patients (pts) with nonischemic cardiomyopathy (NICM) and VT. Methods and Results We studied 18 pts with NICM and recurrent VT who had abnormal echogenicity identified on ICE imaging. Detailed LV endocardial (ENDO) and epicardial (EPI) electroanatomic mapping was performed in all pts. Low voltage areas (< 1.0mV) in the epicardium were analyzed. ICE imaging in the NICM group was compared to a control group of 30 pts with structurally normal hearts who underwent ICE imaging for other ablation procedures. In 18 pts (53 ± 13 years, 17 men) with NICM (EF: 37 ± 13%) increased echogenicity was identified in the lateral LV by ICE imaging. LV ENDO electroanatomic mapping identified normal voltage in 9 pts and at least one, confluent low voltage area [6.6 cm2 (minimum 2.1 to maximum 31.7 cm2)] in 9 pts (5 posterolateral LV and 4 perivalvular LV). Detailed EPI mapping revealed areas of low voltage [39 cm2 (minimum 18.5 to maximum 96.3 cm2)] and abnormal, fractionated electrograms (EGMs) in all 18 pts (15 posterolateral LV and 3 lateral LV). In all pts, the EPI scar identified by electroanatomic mapping correlated with the echogenic area identified on ICE imaging. ICE imaging identified no areas of increased echogenicity in the control group. Conclusions ICE imaging identified increased echogenicity in the lateral wall of the LV that correlated to abnormal EPI substrate. These findings suggest that ICE imaging may be useful to identify EPI substrate in NICM.

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