RESUMO
Extracardiac factors such as respiration, fluid overload and body habitus have important effects on the ECG voltage. Vectorcardiographic (VCG) Global Electrical Heterogeneity (GEH) is associated with sudden cardiac death (SCD). Risk of SCD is especially high in end-stage renal disease patients (ESRD) on dialysis. However, extracardiac factors challenge ECG interpretation in ESRD patients. The effects of extracardiac factors on GEH have not been fully studied. To1 assess effects of extracardiac factors on ECG, we conducted a multi-scale study. An experimental data of ESRD patients and a previously developed biophysically detailed heart-torso model were used to investigate the effects of respiration, fluid overload and body habitus on the VCG and GEH.
RESUMO
BACKGROUND: Global electrical heterogeneity (GEH) is a useful predictor of adverse clinical outcomes. However, reproducibility of GEH measurements on 10-second routine clinical ECG is unknown. METHODS: Data of the prospective cohort study of incident hemodialysis patients (n=253; mean age 54.6±13.5y; 56% male; 79% African American) were analysed. Two random 10-second segments of 5-minute ECG recording in sinus rhythm were compared. GEH was measured as spatial QRS-T angle, spatial ventricular gradient (SVG) magnitude and direction (azimuth and elevation), and a scalar value of SVG measured by (1) sum absolute QRST integral (SAI QRST), and (2) QT integral on vector magnitude signal (iVMQT). Bland-Altman analysis was used to calculate agreement. RESULTS: For all studied vectorcardiographic metrics, agreement was substantial (Lin's concordance coefficient >0.98), and precision was perfect (>99.99%). 95% limits of agreement were ±14° for spatial QRS-T angle, ±13° for SVG azimuth, ±4° for SVG elevation, ±14 mV*ms for SVG magnitude, and ±17 mV*ms for SAI QRST. SAI QRST and iVMQT were in substantial agreement with each other. CONCLUSION: Reproducibility of a 10-second automated GEH ECG measurements was substantial, and precision was perfect.
