Pranav Bhagirath

26 Chapter 2 LA structural remodeling - LA fibrosis Detection and quantification of fibrosis in the atrial wall prior to ablation as a part of patient stratification is a controversial topic. Oakes uses a well-documented approach to acquire the 3D LGE and perform the post-processing with the aim of utilizing the amount of fibrotic tissue topredict procedural outcome (7) . Inanother paper theydescribe tailored patient management based upon the pre-ablation LGE patterns ( figure 2 ) (27) . Despite various attempts, other centers have so far been unable to reproduce these results (28;29) . Results of the on-going DEECAF trial should provide new data on this topic. Left atrial appendage thrombus Stroke is a feared complication of AF, associated with a severe reduction in the quality of life. The presence of thrombus in the left atrial appendage (LAA) is considered the most important risk factor for stroke (30;31) .Therefore, excluding an intracardiac thrombus is a pre-requisite in all patients selected for a left sided ablation procedure. Due to its high sensitivity and specificity (100% and 99% respectively), today TEE is considered the gold standard (32) . However, TEE without sedation usually causes great discomfort and, although uncommon, the examination may result in potentially serious complications (33) . A recent meta-analysis of 19 retro- and prospective studies of patients undergoing both TEE and CT for exclusion of thrombus prior to an ablative procedure, revealed a high accuracy for these techniques in detecting LAA thrombus (34) . CT had a weighted mean sensitivity and specificity of 96% of 92% respectively. The positive predictive value and negative predictive value of CT was 41% and 99% respectively. The overall accuracy improved to 99% (PPV 92% and NPV 100%) when delayed phase imaging was used, making CT a non-invasive alternative for TEE under these terms. Only 2 studies have compared CMR and TEE for detection of thrombus (35;36) . Both combined, examined 147 patients and demonstrated a 100% concordance between the two modalities for detection of LAA thrombus. This suggests that adding conventional MRA or early gadoliniumenhancement pulse sequences to a standard CMR examination ensures adequate coverage of the LAA and may potentially substitute TEE in patients eligible for CMR, without a reduction in diagnostic yield ( figure 3 ).