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Revista Colombiana de Cardiología
Print version ISSN 0120-5633
Abstract
MORALES, Juan et al. Inter- and intra-observer agreement in the quantification of the spatial QRS-T angle calculated by visual transformation. A pilot study. Rev. Colomb. Cardiol. [online]. 2020, vol.27, n.5, pp.388-393. Epub July 22, 2021. ISSN 0120-5633. https://doi.org/10.1016/j.rccar.2018.11.002.
Introduction:
The spatial QRS-T angle is the difference between the QRS vector and T vector. The diagnostic and prognostic value of this marker in heart disease is well-known. It is essential to determine whether these measurements are reproducible and reliable in Colombia.
Methods:
Electrocardiograms (ECG) were obtained from 30 adults, regardless of the diagnosis. The measurements were made by two fifth-year medical students, a houseman/ intern, and a cardiologist. They were all re-trained on the measurement of the angle using the visual transformation method.
With blinded identification, they entered the QRS and T measurements into a web application. The angle was estimated from the template of Cortez et al. About 20% of the readers showed an intra-observer agreement and an inter-observer agreement in 100%. The cut-off points to estimate the agreement Kappa were < 105° (normal), 105° a 135° (borderline), and >135° (abnormal).
Results:
One ECG was excluded due to poor quality. The range of the angle was between 72.9° and 176.2°. The inter-observer agreement between the 4 evaluators gave a kappa = 0.786 (95% CI; 0.728-0.823, P < .0001), and the intra-observer agreement a kappa = 1.0 (P = .007).
Conclusion:
This the first study on the spatial QRS-T angle performed in Colombia. A good inter- and intra-observer agreement was achieved in the measurement of the angle by the visual transformation method by observers with different levels of expertise, with a Kappa greater than 0.75. These results support the reproducibility of this measurement in subsequent studies in Colombia.
Keywords : QRS-T Angle; Reproducibility of results; Electrocardiography; Vectorcardiography.