The sensitivity of graphic trends in differentiating sinus and supraventricular tachycardia

The use of cardiac telemetry in the inpatient setting is widespread and has become integral in managing hospitalized patients. Telemetry is used to monitor patients with brady- and tachyarrhythmias. While most of the focus is on the rhythm strip data, a significant utility remains in analyzing the graphic heart rate trends. We specifically focused on the shape of the curve (rectangle or bell) of the heart rate over time to differentiate sinus tachycardia (ST) and supraventricular tachycardia (SVT). We hypothesized that identifying the shape of the graphic trend would improve the accuracy of diagnosis.

To demonstrate the simplicity of employing this method for improving the diagnosis of arrhythmia, we had senior medical students evaluate the telemetry strips and graphical trends. We gathered data from the medical student interpretation of 82 strips of in-hospital cardiac telemetry and asked them to differentiate ST and SVT based on the shape of the graphic trend. Each rhythm strip and the graphic trend was interpreted by two clinical cardiac electrophysiology attending physicians and confirmed on a 12‑lead electrocardiogram.

When students were asked to choose between ST and SVT based on the telemetry rhythm strip without graphic trends, 73% of their answers were correct. Diagnostic accuracy improved to 96% correct with the addition of the graphic trend. Depending on the telemetry rhythm strip alone, sensitivity to detect SVT was 75%, with 68% specificity. With the addition of the graphical trend, sensitivity improved to 98% and specificity 100%.

Review of graphical trends, specifically the analysis of onset and offset, allows novice ECG readers to improve the ability to distinguish between ST and SVT.