Testing for a common heart arrhythmia with a shopping cart
We could soon be checking our heart rhythm while doing the grocery shopping, thanks to a device incorporated into the handle of a supermarket cart designed to monitor for atrial fibrillation, a common heart arrhythmia that’s a key risk factor for stroke.
During atrial fibrillation (AF), the most common heart disorder, the upper chambers of the heart (atria) beat chaotically and irregularly, out of sync with the chambers below (ventricles). AF may be episodic – come and go – or be permanent and, for a lot of people, they aren’t aware that they have it. The problem with having AF is that it can lead to the formation of blood clots in the heart, which increases the risk of stroke five-fold.
That’s why researchers from Liverpool John Moores University in the UK developed MyDiagnostick, a cylindrical device that records a single-lead electrocardiogram (ECG) tracing when a participant's hands make contact with the metal electrodes. MyDiagnostick’s internal software analyzes the ECG over a one-minute period while the contact is maintained. To make it as unobtrusive as possible, they decided to embed their device into the handles of supermarket carts.
A total of 2,155 agreed to use the modified cart while shopping in a study called SHOPS-AF. They were asked to hold the handle for at least 60 seconds which, if no irregular heartbeat was detected, lit up green. A researcher double-checked the result by manually checking the person’s pulse. MyDiagnostick lit up red if an irregular heartbeat was detected, at which point an in-store pharmacist checked the person’s pulse manually and using a separate heart monitoring device. The ECGs of those whose reading produced a red light were reviewed by a cardiologist.
Participants were advised of the results, either that they didn’t have AF, the ECG was unclear (they were invited to repeat the experiment), or that they had AF and were provided with a cardiologist appointment within two weeks.
ECG data from 220 participants produced a red light, suggesting AF. For 115, AF was ruled out after review by a cardiologist, 46 ECGs were deemed unclear, and AF was diagnosed in 59 participants, 39 of whom had not previously been diagnosed with the condition.
“This study shows the potential of taking health checks to the masses without disrupting daily routines,” said Ian Jones, lead author of the study. “Over the course of two months, we identified 39 patients who were unaware that they had atrial fibrillation. That’s 39 people at greater risk of stroke who received a cardiologist appointment.”
Although MyDiagnostick was sensitive in detecting AF, with sensitivity levels above 94%, its accuracy needs work. It registered a high number of false positives; with only a quarter to a half of those getting a red light for AF actually having the condition. Further, around half of actual AF cases would’ve been missed using the current algorithm; that is, there were many false negatives. The researchers will continue to work on the device’s accuracy but were content with the number of shoppers willing to use it.
“Nearly two-thirds of the shoppers we approached were happy to use a trolley, and the vast majority of those who declined were in a rush rather than wary of being monitored,” Jones said. “This shows that the concept is acceptable to most people and worth testing in a larger study. Before we conduct SHOPS-AF II, some adjustments are needed to make the system more accurate.”
The researchers say that providing access to a medical professional is crucial to the success of the MyDiagnosticks system.
“Checking for atrial fibrillation while people do their regular shopping holds promise for preventing strokes and saving lives,” said Jones. “A crucial aspect is providing immediate access to a health professional who can explain the findings and refer patients on for confirmatory tests and medication if needed.”
The researchers presented the findings of their study at the Annual Congress of the Association of Cardiovascular Nursing and Allied Professionals (ACNAP) 2023, held in Edinburgh, Scotland.
The study was published in the Journal of Personalized Medicine.