Pranav Bhagirath

223 Appendices SUMMARY In the present thesis, we studied the role of imaging modalities in characterizing arrhythmogenic substrate. In Chapter 1 the scope of the thesis and current challenges in electrophysiology are addressed. Recent technological developments have provided new ways to improve our knowledge about the arrhythmogenic substrate. • Cardiac magnetic resonance (CMR) can provide a comprehensive non-invasive analysis of the cardiac geometry, function and tissue characteristics. • Inverse potential mapping (IPM) can reconstruct cardiac surface potentials from body surface potentials, allowing for a non-invasive electrophysiological study to be performed in an out-patient setting. Experiences gained using these techniques can prove critical for developing more effective ablation strategies. In Chapter 2 weprovideda summaryof the applicationof cardiac imaging for pulmonary vein and left atrial ablation divided in stages. A pre-procedural stage (assessment of left atrial dimensions, left atrial appendage thrombus and pulmonary vein anatomy), peri-procedural stage (integration of anatomical and electrical information) and post- procedural (evaluation of efficacy by assessment of tissue properties) stage. CMR was found to be comparable to the other key imaging modalities, providing all the information during a single examination, in a safe and reproducible manner. In Chapter 3 we described a benchmarking evaluation framework for quantifying late gadolinium enhancement images. Six widely-used fixed-thresholding methods and five recently developed algorithms were compared. Results demonstrated that the algorithms have better overlap with the consensus ground truth than most of the fixed- thresholding methods, with the exception of the Full-Width-at-Half-Maximum fixed- thresholding method. As infarct quantification is an important assessment criterion for many cardiac therapies, it is advisable to compare new algorithms using the proposed benchmark prior to clinical implementation. In Chapter 4 we investigated the feasibility and clinical applicability of a standardized CMR basedworkup for atrial fibrillation (AF) ablation. The acquisition using commercially available sequences and post-processing of the CMR images with open-source software was possible in less than 45 minutes. Although not all discontinuous regions of scar showed electrical activity, the majority of the invasively measured electrical gaps