LAUSR

We read with interest two manuscripts in this journal both exploring the effect of a multimodality imaging approach to guide LV lead implantation for delivery of CRT. Suboptimal LV lead positioning is a well established contributor to poor CRT response and, as such, techniques utilizing cardiac imaging to avoid areas of myocardial fibrosis1 and/or target dyssynchrony2 have been of great interest. The studies by Sommer et al.3 and Bertini et al.4 take an interesting approach by combining the strengths of different imaging modalities to guide LV lead placement and, in so doing, reporting a reduction in the proportion of patients with a suboptimal response to CRT. While these results are certainly encouraging, one of the major limitations is that the data output from the imaging modality in each study is reviewed separate from, and alongside, X-ray rather than integrated together. Given the radiolucency of the cardiac silhouette and high variability in the rotation of the leftand right-sided chambers relative to one another, it is not altogether surprising that using fluoroscopy to determine regional anatomy can be highly inaccurate, particularly with regard to CRT and lead position.5 The next logical step is the co-registration of cardiac imaging data with X-ray; the resulting visual integration is likely to facilitate more accurate image guidance for cardiac procedures. Our group has, indeed, designed a purpose-built platform which enables real-time cardiac magnetic resonance imaging (MRI)-defined scar and dyssynchrony analysis to guide LV lead implantation.6 Rapidly evolving technology is enabling real-time image fusion to become a reality for an increasing number of cardiac centres using cardiac MRI, echocardiography, and electro-anatomical mapping; future image-guided CRT studies should incorporate this highly valuable and translational clinical application.