Young Investigators Competition1Left ventricular lead position, mechanical activation and myocardial scar in relation to the clinical outcome of cardiac resynchronisation therapy: the role of feature-tracking and contrast-enhanced cardiovascular magnetic resonance2Does the haemodynamic improvement of biventricular pacing truly arise from cardiac resynchronisation? quantifying the contribution of av and vv adjustment3Differential relationship of electrical delay with endocardial and epicardial left ventricular leads for cardiac resynchronisation therapy4Characterisation of the persistent af substrate through the assessment of electrophysiologic parameters in the organised vs. disorganised rhythm5Targeting cyclical highest dominant frequency in the ablation of persistent atrial fibrillation6Feasibility of fully mr-guided ablation with active tracking: from pre-clinical to clinical application

Introduction: Late mechanical activation (LMA) and myocardial viability have been proposed as targets for left ventricular (LV) pacing during cardiac resynchronisation therapy (CRT).Feature-tracking (FT) cardiovascular magnetic resonance (CMR), the CMR equivalent of speckle-tracking echocardiography, has been validated against the gold-standard of CMR-tagging for the assessment of myocardial deformation.Late gadolinium enhancement (LGE) CMR is the gold-standard for myocardial scar imaging.We hypothesised that deployment of the LV lead over nonscarred segments with LMA, assessed using LGE-CMR and FT-CMR, portends a better outcome from CRT. Methods: 89 patients who underwent successful CRT device implantation were recruited through a dedicated heart failure (HF) device clinic from a single centre.Patients required a pre-implantation CMR scan for inclusion.FT-CMR of the basal, mid and apical short axis slices was used to determine the LMA segment; that with the latest peak systolic circumferential strain within the imaged cardiac cycle.Only the 11 free wall segments were considered.The presence or absence of myocardial scar was recorded in each segment based on visual assessment of LGE-CMR short axis slices.The LV lead tip was mapped to a specific segment based on fluoroscopic acquisitions in the right anterior (RAO) and left anterior (LAO) projections at the time of implantation.Lead positions were classified into concordant (no scar and LMA) or non-concordant (scar and/or earlier-activated segments).Results: 89 patients (age: 66.8 + 10.8 yrs, LVEF: 23.1 + 9.9%, QRS: 149.0 + 25.7 ms) were followed up for a median of 4.2 years.LV reverse remodelling (LVRR) occurred in 68% and 24% of patients with concordant and non-concordant LV lead positions respectively (p , 0.001).LMA in the paced segment was the strongest predictor of LVRR (OR: 18.9; 95%C.I. 3.84-84.31).LV lead concordance predicted cardiac mortality (Log Rank [LR] x 2 ¼ 7.32, p¼ 0.007; hazard ratio [HR]: 0.27, 95% C.I. 0.12-0.62)(Figure 1) and cardiac mortality or hospitalisations for HF (LR x 2 : 8.31, p , 0.004; HR: 0.26, 95% C.I. 0.12-0.58).'No scar' in the paced segment predicted cardiac mortality (HR: 0.24, 95% C.I. 0.11-0.52)and cardiac mortality or HF hospitalisations (HR: 0.24, 95% C.I. 0.12-0.49).LMA in the paced segments did not predict these endpoints.Conclusion: A LV lead position over segments with LMA and no scar is associated with a better clinical outcome and LVRR after CRT.Clinical events were primarily related to scar, whereas LVRR was primarily related to LMA.These findings support the combined use of LGE-CMR and FT-CMR in guiding LV lead deployment.