December 13, 2019IEEE Journal of Translational Engineering in Health and MedicineOpen Access

Accuracy of the Apple Watch 4 to Measure Heart Rate in Patients With Atrial Fibrillation

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Why the study?

Previous evaluations of wearable wrist-monitors focused on healthy subjects during exercise, leaving their efficacy unassessed in patients with common cardiac arrhythmias such as atrial fibrillation.

Does the Apple Watch 4 accurately measure heart rate compared to continuous telemetry in post-operative cardiac surgery patients with and without atrial fibrillation?

Structured PICO

Does the Apple Watch 4 accurately measure heart rate compared to continuous telemetry in post-operative cardiac surgery patients with and without atrial fibrillation?

Population

50 post-operative cardiac surgery patients admitted to cardiac telemetry step-down floors, mean age 61.4, 28% women. 50% experiencing atrial fibrillation and 50% experiencing sinus rhythm at enrollment. Exclusion criteria: cardiac pacemaker, use of a radial artery graft for CABG, known chronic or persistent heart rhythm disorders, and tattoos on the wrist or forearm.

Intervention

Apple Watch 4 (AW4) heart rate monitor, placed on randomly assigned wrist for no more than five minutes, with a minimum of three assessments per day for at least two days.

Comparator

Continuous six-lead telemetry (standard clinical practice).

Outcome

Accuracy of heart rate measurement (Lin's concordance correlation coefficient) between the Apple Watch 4 and telemetry.surrogate

The Apple Watch 4 showed moderate overall agreement with telemetry for heart rate monitoring in post-operative cardiac patients, suggesting caution should be used before relying on it for clinical decision-making in patients with arrhythmias.

Limitations

Patients had to manually press the button to obtain a reading, requiring awareness of AF symptoms
Fluid overload and edema following surgery could affect accuracy
Interference with other medical equipment on or near the patient

Implication

Supports wearable HR monitoring feasibility in AF; leaves open accuracy for clinical decisions pending larger validation.

Abstract

Background Wearable wrist-monitors offer an unobtrusive way to acquire heart rate data in an efficient manner. Previous work in this field has focused on studying healthy subjects during exercise but has yet to assess the efficacy of these devices in patients suffering from common cardiac arrhythmias such as atrial fibrillation. Objective The objective of this pilot study was to assess the accuracy of the Apple Watch heart rate monitor in fifty patients experiencing atrial fibrillation compared to telemetry. Results Results from this pilot clinical study demonstrated a correlation coefficient of 0.7 between all readings on the Apple Watch and telemetry. Furthermore, the Apple Watch assessed heart rate more accurately in patients who were in atrial fibrillation than in those that were not (rc = 0.86, patients in AF, vs. rc = 0.64, patients not in AF). Clinical Impact The presented data from this pilot study suggests that caution should be noted before using the Apple Watch 4 wearable wrist monitor to monitor heart rate in patients with cardiac arrhythmias such as atrial fibrillation.