Andrew Roberts's research while affiliated with The University of Calgary and other places

Background . The placement of the left ventricular (LV) lead in an area free of myocardial scar is an important determinant of cardiac resynchronization therapy (CRT) response. We sought to develop and validate a simple, practical and novel electrocardiographic (ECG) based approach to intra-operatively identify the presence of LV scar. We hypothesized that there would be a reduction in the measured amplitude of the LV pacing stimulus on the skin surface using a high-resolution (HR) ECG when pacing from LV regions with scar compared to regions without scar. We term this the ECG Amplitude Signal Evaluation (EASE) method. Methods . Consecutive patients with ischemic LV systolic dysfunction and standard criteria for de novo CRT implantation were prospectively enrolled. All underwent a pre-implant enhanced cardiac magnetic resonance (CMR) study to assess for scar. The average amplitude of the LV pacing impulse was sampled on HR surface ECG intra-procedurally and then blindly compared to the CMR results. Results . A total of 38 LV pacing sites were assessed among 13 recipients. The median voltage measured on the surface HR ECG in regions with scar were reduced by 41% (interquartile range [IQR] 17% to 63%), while there was no measurable change in voltage (IQR 0 to 0%) in regions without scar as compared to the maximal amplitude (Wilcoxon p<0.0001). Conclusion . The EASE method appears to be of potential value as a novel intra-operative tool to guide LV lead placement to regions free of scar. Future work is required to validate the utility of this method in a larger patient cohort.

Background In this study we aimed to investigate left atrial (LA) function, measured from routine cine cardiovascular magnetic resonance imaging, to determine its value for the prediction of sudden cardiac death (SCD) or appropriate implantable cardioverter defibrillator (ICD) shock in patients who received primary prevention ICD implantation. Methods We studied 203 patients with ischemic or idiopathic nonischemic dilated cardiomyopathy who underwent cardiovascular magnetic resonance imaging before primary prevention ICD implantation. LA volumes were measured at end-diastole and end-systole from 4- and 2-chamber cine images, and LA emptying function (LAEF) calculated. Patients were followed for the primary composite end point of SCD or appropriate ICD shock. Results Mean age was 61 ± 12 years with a mean left ventricular ejection fraction of 24 ± 7%. The mean LAEF was 27 ± 15% (range, 0.9%-73%). At a median follow-up of 1639 days, 35 patients (17%) experienced the primary composite outcome. LAEF was strongly associated with the primary outcome (P = 0.001); patients with an LAEF ≤ 30% experienced a cumulative event rate of 26.1% vs 5.7% (hazard ratio, 5.5; P < 0.001) in patients above this cutoff. This finding was maintained in multivariable analysis (hazard ratio, 4.7; P = 0.002) and was consistently shown in the ischemic and nonischemic dilated cardiomyopathy subgroups. Conclusions LAEF is a simple, powerful, and independent predictor of SCD in patients being referred for primary prevention ICD implantation.