Pseudo-colouring an ECG enables lay people to detect QT-interval prolongation regardless of heart rate

Abstract

Drug-induced long QT syndrome (diLQTS), characterized by a prolongation of the QT-interval on the electrocardiogram (ECG), is a serious adverse drug reaction that can cause the life-threatening arrhythmia Torsade de Points (TdP). Self-monitoring for diLQTS could therefore save lives, but detecting it on the ECG is difficult, particularly at high and low heart rates. In this paper, we evaluate whether using a pseudo-colouring visualisation technique and changing the coordinate system (Cartesian vs. Polar) can support lay people in identifying QT-prolongation at varying heart rates. Four visualisation techniques were evaluated using a counterbalanced repeated measures design including Cartesian no-colouring, Cartesian pseudo-colouring, Polar no-colouring and Polar pseudo-colouring. We used a multireader, multi-case (MRMC) receiver operating characteristic (ROC) study design within a psychophysical paradigm, along with eye-tracking technology. Forty-three lay participants read forty ECGs (TdP risk n = 20, no risk n = 20), classifying each QT-interval as normal/ abnormal, and rating their confidence on a 6-point scale. The results show that introducing pseudo-colouring to the ECG significantly increased accurate detection of QT-interval prolongation regardless of heart rate, T-wave morphology and coordinate system. Pseudocolour also helped to reduce reaction times and increased satisfaction when reading the ECGs. Eye movement analysis indicated that pseudo-colour helped to focus visual attention on the areas of the ECG crucial to detecting QT-prolongation. The study indicates that pseudo-colouring enables lay people to visually identify drug-induced QT-prolongation regardless of heart rate, with implications for the more rapid identification and management of diLQTS.

An explainable algorithm for detecting drug-induced QT-prolongation at risk of torsades de pointes (TdP) regardless of heart rate and T-wave morphology

“…The comparison with human interpretation was conducted by testing the expert algorithm on ECGs ( = 40) used in a previous study conducted with humans to evaluate the pseudo-colouring technique [4]. The ECGs were…”

“…We have shown in previous work that superimposing pseudo-colouring, a technique that represents continuously varying values using a sequence of colours [80], on the ECG signi cantly improves people's ability to detect QT-prolongation at risk of TdP, regardless of heart rate [4]. Our technique draws from the eld of pre-attentive processing theory in human vision, which outlines a set of visual properties including colour that can be detected rapidly and accurately by the human eye [32,33,81].…”

“…Figure 2 shows examples of ECGs with pseudo-colouring that have di erent heart rates, but similar levels of TdP risk according to QTinterval; the dashed lines represent the QT nomogram line value at risk of TdP for a given heart rate. More details about the pseudo-colouring technique and its evaluation can be found in [3,4].…”

“…The source code of the decision tree classi cation model can be found in [5]. Finally, we compared the classi cation accuracy of the expert algorithm with the results of a previous study conducted with humans [4].…”