Monitoring heart rhythms in adult males with X-linked ichthyosis using wearable technology: a feasibility study

Background: The rare dermatological condition X-linked ichthyosis (XLI) is typically caused by Xp22.31 microdeletions and has recently been linked to a substantially-increased risk of cardiac arrhythmias; arrhythmias predispose to multiple health conditions with long-term implications including heart failure, stroke, and accelerated cognitive decline. To optimise therapeutic outcomes, there is a need to identify individuals experiencing arrhythmias at an early stage, ideally using non-invasive, convenient, cost-effective, and reliable wearable technology methods. Methods: We tested the feasibility of monitoring heart rhythms using an Apple Watch Series 8 in five adult males from the United Kingdom previously diagnosed with XLI. Participants were asked to return routine electrocardiogram (ECG) traces from the watch three times per week over an eight week period (plus any traces associated with watch alerts indicating arrhythmic episodes) for review by experienced cardiologists. Feedback was also obtained from participants on the perceived usability/wearability of the watch/app, and on the requirements of the study. Results: Participants were generally happy with undertaking the study procedures and found the watch/app straightforward to use; consequently there was a very high data return rate (>95%). Some minor suggestions were made regarding protocol improvements. There were few issues with wearability of the watch, including with respect to skin irritation, although one participant did report finding the sensation of wearing the watch continuously somewhat overwhelming. Three participants exhibited no ECG abnormalities, but two presented with ventricular ectopic beats (VEs); one participant presenting with a particularly high burden of VEs was advised to contact his doctor. Only one watch ‘alert’ ECG was returned, and this was considered normal sinus rhythm, suggesting the possibility of ‘false positive’ calls. Conclusions: Screening for cardiac rhythm abnormalities using smartwatches in the high-risk adult male XLI population appears useful, feasible, and acceptable to patients and a larger-scale clinical trial may be warranted (as may a similar feasibility trial in younger males with XLI). Potentially, such devices may be more suited to detecting persistent abnormalities rather than unpredictable, acute, arrhythmic episodes. The presence of high numbers of VEs in some participants with XLI is consistent with the idea of septal defects mediating arrhythmia risk.