1030Role of cardiac magnetic resonance and echocardiography prior to cardiac resynchronization therapy

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Purpose: Cardiac resynchronization therapy is an established method for treatment of patients with heart failure. Optimal left ventricular lead implantation guided by novel imaging techniques appears to be a promising method to increase the response to this therapy. Methods: 29 patients scheduled for cardiac resynchronization therapy underwent detailed ECHO and cardiac magnetic resonance studies prior to CRT device implantation. The aim of the imaging studies was to determine an optimal pacing site for the left ventricular lead placement. The off-line analysis was performed by two experienced readers in a blinded fashion. CMR was performed on 3T system (Siemens). Cine, late gadolinium enhancement and myocardial tagging sequences were acquired. Image software Segment (Sweden) was used for left ventricular segmentation. Left ventricular wall motion and myocardial scar analysis were performed in all 17 segments . Tagging sequences were analysed with inTag (Universite de Lyon) in short axis slices at basal, mid ventricular and apical levels of the left ventricle. The care was taken to ensure correct alignment of these slices to achieve the same segmentation as with echocardiography. Standard echocardiographic parasternal and apical views were stored and analysed off-line. Left ventricular radial, longitudinal and circumferential strains were assessed using commercially available software (EchoPac 6.1). The cut-off value for regional longitudinal strain was – 4.5% to discriminate between transmural (>50%) and nontransmural (<50%) myocardial scar (Roes S.D., Mollema S.A., Bax J.J., Am J Cardiol 2009;104;312-317). Results: Wall motion analysis was possible in all 493 segments in CMR and in 472 (96%) in echocardiography studies. Mean ejection fraction of the left ventricle was 29 ± 5 % when assessed by echocardiography and 23 ± 9 % in CMR studies (P = 0.0005). The average LV EDVi was 99 ± 21 ml/m2 (ECHO) and 115 ± 32 ml/m2 (CMR) (P = 0.003). Scar transmurality was significantly overestimated by ECHO using the longitudinal strain cut-off -4.5% for discrimination between transmural and nontransmural scar – 2.8 times. The dyssynchrony analysis targeted to define the latest activated LV segment showed significant agreement between the two methods. The exact segments agreement was detected in 19 cases (66%). In 6 cases (21%) targeted segment was ± 1 neighbour segment. Discordance between the latest activated segment was detected in 4 patiens (14 %). Conclusions: We have demonstrated that CMR has a potential to improve diagnostic preoperative assessment in patients with severe heart failure and might be a useful tool for LV dyssynchrony assessment. CMR is an excellent method for scar assessment and is a useful tool for LV strain analysis.