APPLE watch picks-up Epsilon waves of ARVD, an EHJ case report.
Figure showing conventional ECG and ECG from smartwatch.
Wearable health devices are becoming increasingly popular. The Apple Watch series 4 and 5 are the first wearable devices allowing individuals to generate electrocardiograms (ECGs) using the ECG app.
According to the new 2010 Task Force criteria, epsilon waves are a major criterion in the diagnosis of arrhythmogenic right ventricular dysplasia (ARVD). Epsilon waves can be observed in the right precordial leads when a relevant intramyocardial conduction defect is present in the right ventricle.
A 32-year-old man with a family history of sudden cardiac death due to arrhythmogenic cardiomyopathy (ACM) was admitted following a recovered ventricular fibrillation cardiac arrest. A family genetic study had detected that the patient carried a mutation on the desmoplaquin gene.
Transthoracic echocardiography revealed a moderately dilated right ventricle with distal hypertrabeculation and decreased systolic function. The left ventricle was also dilated and showed impaired global systolic function. A conventional 12‐lead electrocardiogram (ECG) was performed showing sinus rhythm, a slight deflection at the end of the QRS in V1–V2, and T-wave inversion in lateral leads.
In addition to standard ECG, quasistandard precordial leads were obtained with an Apple Watch Series 5, displaying intraventricular conduction delay, a low amplitude small deflection between the terminal portion of QRS complex, and the onset of the T wave in all precordial leads, as well as T-wave inversion in lateral leads (Figure).
This small deflection corresponds to an epsilon wave representing a post-excitation phenomenon of the myocytes in both ventricles.
Obtaining an ECG using an Apple Watch is as easy as opening the ECG app and touching the digital crown with a finger. The watch then records 30 seconds of a "single-channel ECG similar to a lead I ECG". An associated app (ECG app) in the iPhone (Apple) can do a rhythm analysis and classify the recording as sinus rhythm, bradycardia, tachycardia, or atrial fibrillation or as inconclusive.
The Apple Watch registers precordial leads using an electrode on the right arm as negative pole, instead of using the classical Wilson's central terminal pole. Additionally, the output signal filter is higher (511 Hz) when compared with the conventional ECG. Despite technical differences, the resulting tracing is similar to the conventional one.
In conclusion, the Apple Watch can detect ECG pathological changes like epsilon waves thus contributing to the diagnostic of ACM.
Source: European Heart Journal: case reports. Epsilon wave detected by an Apple Watch Series 5 in a patient with biventricular arrhythmogenic cardiomyopathy, European Heart Journal - Case Reports, Volume 5, Issue 2, February 2021, ytab019, https://doi.org/10.1093/ehjcr/ytab019
