Wearable Tech for Cardiac Arrhythmia

Our heart rhythm clinics may be able to use your existing smart watch or smartphone to diagnose and monitor cardiac arrhythmias, including atrial fibrillation (AF). We routinely work with data from devices such as Apple Watch, Withings, Fitbit and the Fibricheck app.

Smart wearables have three potential functions in the diagnosis and management of arrhythmia. At their most basic, devices can produce a graph of heart rate over time. We find this information most useful for risk stratifying for diagnoses such as supraventricular tachycardia or pathological bradycardias. Occasionally, nocturnal heart rate patterns may raise suspicion of disordered sleep due to disorders such as sleep apnoea. In general, heart rate data on its own is rarely sufficient to make or confirm a diagnosis and further tests are usually needed.

The second layer of functionality is the ability to constantly monitor the heart beat and automatically tag periods of irregularity. Here, manufacturers have concentrated on algorithms for diagnosis of atrial fibrillation. All major manufacturers’ ranges (Apple, Withings, Fitbit) now include models with this function. This can be highly accurate.

A third function that we find particularly useful is the ability of some smart devices to record medical-grade ECG, typically for a 30 second snapshot of cardiac electrical activity. All major manufacturers now provide wearables with this feature, but the specifics of how to record the ECG, and how long recordings can be made for, vary. Importantly, this feature is only useful for patients who experience symptoms with their arrhythmia: unlike a constant heart rate monitoring function it will not diagnose “in the background” but requires the user to trigger an ECG recording. Once the recording is made, it is generally straightforward to share it (for example as a PDF) with your heart rhythm specialist for review, to reach a diagnosis. Some devices also include an automatic interpretation algorithm for ECGs recorded in this way.

Devices such as the Kardia AliveCor can add ECG recording functionality to a non-ECG smartphone, converting older tech into a top quality ECG recorder.

One final innovation in this exciting area is FibriCheck: this app uses a smartphone’s built in camera to diagnose AF from the pattern of blood flow in the fingertip, without the need for any specific hardware. Importantly, the technology here is so groundbreaking that the manufacturers do recommend that any diagnoses made with FibriCheck are confirmed by more conventional means. In practice, we are very happy to take a FibriCheck diagnosis as a starting point for further investigation in people without previous known AF.