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Background Predicting clinical outcomes after cardiac resynchronization therapy ( CRT ) and its optimization remain a challenge. We sought to determine whether pre‐ and postimplantation QRS area ( QRS area ) predict clinical outcomes after CRT . Methods and Results In this retrospective study, QRS area , derived from pre‐ and postimplantation vectorcardiography, were assessed in relation to the primary end point of cardiac mortality after CRT with or without defibrillation. Other end points included total mortality, total mortality or heart failure ( HF ) hospitalization, total mortality or major adverse cardiac events, and the arrhythmic end point of sudden cardiac death or ventricular arrhythmias with or without a shock. In patients (n=380, age 72.0±12.4 years, 68.7% male) undergoing CRT over 7.7 years (median follow‐up: 3.8 years [interquartile range 2.3–5.3]), preimplantation QRS area ≥102 μVs predicted cardiac mortality ( HR : 0.36; P QRS duration ( QRS d) and morphology ( P QRS area reduction ≥45 μVs after CRT predicted cardiac mortality ( HR : 0.19), total mortality ( HR : 0.50), total mortality or heart failure hospitalization ( HR : 0.44), total mortality or major adverse cardiac events ( HR : 0.43) (all P HR : 0.26; P QRS area and QRS d was associated with the lowest risk of cardiac mortality and the arrhythmic end point (both HR : 0.12, P Conclusions Pre‐implantation QRS area , derived from vectorcardiography, was superior to QRS d and QRS morphology in predicting cardiac mortality after CRT . A postimplant reduction in both QRS area and QRS d was associated with the best outcomes, including the arrhythmic end point.

Background: Data from reduced lead ECG configurations can be transformed to reconstruct a 12-lead ECG. The sensing electrodes of a subcutaneous ICD (S-ICD) could provide a suitable basis for such a system. Reconstruction of a 12-lead ECG from conventional S-ICD vectors has not previously been demonstrated. Hypothesis: A 12-lead ECG signal can be accurately derived from S-ICD electrode vectors. Methods: Participants with ICDs (N=61) underwent 3 minute ECGs with electrodes in the standard S-ICD and 12-lead positions. Participants were randomised to either a training (N=31) or validation (N=30) group. Two participants and one further lead were subsequently excluded from the validation group due to technical faults. The transformation was a linear combination of the 2 independent S-ICD vectors to each of the 8 independent leads of the 12-lead ECG, with coefficients selected that minimized the root mean square error (RMSE) between recorded and derived ECGs when applied to the training group. The transformation was then applied to the validation group and agreement between the recorded and derived lead pairs was measured by Pearson correlation coefficient (r) and normalised RMSE (NRMSE). Results: In total, 335 lead pairs were compared (figure1). Distribution of r and NRMSE were skewed. Mean r = 0.731 (SE 0.021), Median r = 0.903 (SE 0.015). NRMSE Mean = 0.227 (SE 0.011) Median = 0.167 (SE 0.008). 252/335 (75.2%) of all pairs had an r > 0.7 (indicating very strong positive correlation). Figure 1: Example 12-lead ECG, recorded (blue line) and derived (red line). Participant randomly selected from top 20% by mean Pearson correlation coefficient. Conclusions: We have demonstrated reconstruction of a 12-lead ECG from S-ICD vectors. The agreement between derived and measured signals was generally excellent and comparable with other widely accepted reduced lead systems. If perfected, the ability to generate 12-lead data from an S-ICD could help clinicians to localise and treat arrhythmias.

Background. Previous studies have reported dyssynchrony using Tissue Doppler in patients with hypertrophic cardiomyopathy (HCM). In this study we assessed dyssynchrony using speckle tracking echocardiography (STE) in patients with non-obstructive hypertrophic cardiomyopathy vs a healthy control group and in a subgroup of highly symptomatic patients evaluated the acute effects of biventricular pacing on STE and Tissue Doppler (TDI) derived measures of dyssynchrony. Methods. We studied 48 healthy controls (age 48 ±18yrs, 22 males, LVEF 63 ±5%, QRS 86 ±7ms) and 57 patients with HCM (age 54 ±11yrs, 38 males, LVEF 61 ±7%, QRS 110 ±36ms). A subgroup of 15 symptomatic patients with HCM (Peak VO2 Results. Using STE, Tϵ-SD (54.99 ±33.61ms vs 24.55 ±21.18ms p . (All values expressed as mean ±SD) Conclusion. Cardiac resynchronisation therapy significantly reduced dyssynchrony in symptomatic patients with non-obstructive HCM as demonstrated using STE and TDI. Table

Aims: Studies on cardiac resynchronization therapy (CRT) for heart failure have shown a differential response in patients with ischemic (ICM) and non-ischemic cardiomyopathy (NICM). Increasing dyssynchrony has been shown to relate to a poor prognosis in patients with heart failure. We hypothesized that ICM and NICM have varying effects on left ventricular (LV) synchrony. Methods: The recently described cardiovascular magnetic resonance tissue synchronization index (CMR-TSI), which predicts benefit from CRT, was quantified in 181 patients (age: 66.4 ± 10.6 yrs, NYHA class III or IV, LVEF: 23.5 ± 10.8%, QRS = 139.8 ± 32.0 ms) with ICM (n=105) or NICM (n=76) and age-matched, healthy controls (n=24). The maximum time-to-peak radial wall motion in a short axis stack of LV images (steady-steady free precession imaging) was fitted to an empirical sine wave [y = a + b * sin (t/RR + c)]. The CMR-TSI was calculated as the SD of all segmental phase shifts of the radial wall motion extracted from this wave (see Figure for bull’s eye maps). Results: CMR-TSI was higher in ICM (105.8 ± 44.2, ANOVA p ). In multivariate analyses including ICM and NICM patients only, ischemic aetiology emerged as a positive predictor of CMR-TSI, independent of QRS duration, LV end-systolic and end-diastolic volumes, and LVEF (all p Conclusions: ICM is associated with a greater degree of dyssynchrony than NICM, independently of QRS duration, LV volumes and LVEF. These findings may account for the differential response to CRT observed with patients with ICM and NICM.