Can lay people identify a drug-induced QT-interval prolongation? A psychophysical and eye-tracking experiment examining the ability of non-experts to interpret an ECG

Objective To quantify a lay person’s ability to detect drug-induced QT-interval prolongation on an ECG and to determine whether the presentation of the trace affects such detection.
Materials and methods Thirty lay participants took part in a psychophysical and eye-tracking experiment. Following training, participants completed 21 experimental trials, where each trial consisted of two ECGs (a baseline and a comparison stimulus, both with a 60 BPM heart rate). The experiment used a one alternative forced-choice paradigm, where participants indicated whether or not they perceived a difference in the QT-interval length between the two ECGs. The ECG trace was presented in three ways: a single complex with the signals aligned by the R wave; a single complex without alignment; a 10-second rhythm strip. Performance was analysed using the psychometric function to estimate the just noticeable difference (JND) threshold, along with eyetracking
metrics.
Results The JND 50% and 75% thresholds were 30 and 88 milliseconds respectively, showing that the majority of lay people were able to detect a clinically significant QT-prolongation at a low normal heart rate. Eye movement data indicated that people were more likely to appraise the rhythm strip stimulus systematically and accurately.
Discussion and Conclusion People can quickly be trained to self-monitor, which may help with more rapid identification of drug-induced LQTS and prevent the development of life-threatening complications. The rhythm strip is a better form of presentation than a single complex, as it is less likely to be misinterpreted due to artefacts in the signal.