Using a Smartwatch to Aid Diagnosis of Syncope

Syncope is a common reason for a clinical visit, with a lifetime prevalence of about 35%.¹ Syncope can elude prompt diagnosis.² In a study of syncopal patients presenting at a primary care teaching hospital, a suspected cause of syncope could only be found in 69% of patients in the first visit.³ However, prompt diagnosis can be crucial because syncope may be caused by any number of conditions, some benign and others potentially life threatening.⁴

This patient presented for the first time at our syncope clinic in March 2019. He was a 43-year-old man in overall good health with a history of ablation about 10 years earlier to address a supraventricular tachycardia (SVT). In the intervening years, he experienced no particular health problems until he passed out. The syncopal spell was witnessed and the patient was brought to the emergency room where he recovered. An electrocardiogram (ECG) taken in the emergency room showed nothing unusual. He had not had a seizure and was not doing anything unusual when the syncope occurred.

A few months earlier, he had received an Apple Watch as a Christmas gift. Although not all Apple Watches offer this feature, his particular watch was equipped with a heart rate monitor along with an activity tracker. Once or twice before his syncopal episode, he had noticed that the heart rate on his watch had run up to about 225 or 230 beats per minute (bpm) even though he was not exerting himself at the time. During those two episodes, he reported feeling dizzy but did not lose consciousness. The Apple Watch could not provide those tracings and there was no ability to save ECGs into its memory.

After the patient’s history was taken at the clinic, he underwent a 12-lead ECG examination and an echocardiogram, which turned out to be normal and did not reveal anything that could explain his symptoms. He later underwent a stress test, which suggested a question on the anterior wall but nothing particularly alarming. A five-day Holter monitor was ordered, but nothing remarkable was found. The patient was concerned that he might faint again, and it was important to figure out the etiology of his syncope.

For several months, the patient was asymptomatic and felt fine, but he was concerned that he might faint again. That summer, the decision was made to provide long-term rhythm monitoring. A BIOMONITOR III (BIOTRONIK) injectable cardiac rhythm monitor was chosen to get a better assessment of the patient’s cardiac activity. This device has a four-year battery life and has the capability to discriminate different kinds of arrhythmias. The device was injected under local anesthetic in a five-minute procedure in the clinic. The patient was given a bedside device for a Home Monitoring system (BIOTRONIK) which transmits data from the BIOMONITOR III to the Home Monitoring Service Center securely with no patient interaction required, as well as an app for his smartphone to help annotate symptoms. Both of these devices receive information from the BIOMONITOR III and transmit it securely to the clinic with no patient interaction.

After less than a week, the BIOMONITOR III detected a wide-complex ventricular tachycardia at around 210 bpm. The patient had not experienced symptoms and the arrhythmia spontaneously terminated. The patient returned to the clinic and underwent a cardiac catheterization, which found no blockage in his coronary arteries. He was prescribed medication and has had no recurrence. The BIOMONITOR III remains in place and provides continuous observation of his future rhythm and response to treatment.

The Apple Watch is an important new tool that is increasingly being used by clinic patients. As an activity monitor, the Apple Watch has been evaluated for validity during exercise and was found to be more valid for heart rates during walking than running or performing more intense exercises.⁵ A variety of personal cardiac monitors are currently available, including small handheld devices that can capture an ECG. In a study comparing various systems, positive predictive value for these consumer devices was 39.9% for atrial fibrillation, a rhythm that carries a risk of stroke.⁶ These devices can be very helpful in quantifying certain symptoms or providing evidence of arrhythmic activity, but should not be regarded as true diagnostic tools.⁷ When used to help patients identify cardiac arrhythmias and provide a symptom-rhythm correlation, they provide and fulfill an important and previously unmet need in patient care. They are being seen increasingly in ambulatory clinic patients, and give providers a better and more objective look at past rhythms and their response to treatment. 

This article is published with support from BIOTRONIK.

Disclosure: Dr. Evans has no conflicts of interest to report regarding the content herein. Medical writer Jo Ann LeQuang helped edit this article; her services were paid by BIOTRONIK.

Visit diagnostics.biotronik.com to learn more about BIOMONITOR III.

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2. Brignole M, Alboni P, Benditt DG, et al. Guidelines on management (diagnosis and treatment) of syncope-update 2004. Executive Summary. Eur Heart J. 2004;25(22):2054-2072.
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