Improved evaluation of left ventricular hypertrophy using the spatial QRS-T angle by electrocardiography

Background Conventional electrocardiographic (ECG) signs of left ventricular hypertrophy (LVH) lack sensitivity. The aim was to identify LVH based on an abnormal spatial peaks QRS-T angle, and evaluate its diagnostic and prognostic performance compared to that of conventional ECG criteria for LVH. Methods This was an observational study with four cohorts, all with a QRS duration <120 ms: (1) Healthy volunteers to define normality (n=921), (2) Separate healthy volunteers to compare test specificity (n=461), (3) Patients with at least moderate LVH by cardiac imaging (Imaging-LVH) to compare test sensitivity (n=225), and (4) Patients referred for cardiovascular magnetic resonance imaging to evaluate the combined outcome of hospitalization for heart failure or all-cause death (Clinical-Consecutive, n=783). Results An abnormal spatial peaks QRS-T angle was defined as exceeding the upper limit of normal, which was found to be ≥ 40° for females and ≥ 55° for males. In healthy volunteers, the specificity of the QRS-T angle to detect LVH was 96% (females) and 98% (males). In Imaging-LVH, the QRS-T angle had a higher sensitivity to detect LVH than conventional ECG criteria (93–97% vs 13–56%, p <0.001 for all). In Clinical-Consecutive, of those who did not have any LVH, 238/556 (43%) had an abnormal QRS-T angle, suggesting it can occur even without LVH. There was an association with outcomes in univariable analysis for the QRS-T angle, Cornell voltage, QRS duration, and Cornell product (hazard ratios 1.68–2.5, p<0.01 for all) that persisted in multivariable analysis only for the QRS-T angle and QRS duration (p<0.001 for both). Conclusions An increased QRS-T angle rarely occurred in healthy volunteers, was a mainstay of moderate or greater LVH, was common in clinical patients without LVH but with cardiac co-morbidities, and associated with outcomes. Thus, an increased QRS-T angle identifies left ventricular electrical remodeling that can occur in the absence of LVH detected by imaging. The improved diagnostic and independent prognostic performance for the QRS-T angle suggests that it should be investigated when ECGs are evaluated.