Apple Smart Watch ECG Provides ST-Elevation Reading Accuracy

Dr. Ciro Indolfi

Smartwatch electrocardiogram (ECG) could provide as good an identification of ST-segment elevation and depression as a standard ECG device, according to new findings.

Research, presented online during the European Society of Cardiology (ESC) 2020 Congress, showed patients with acute coronary syndromes (ACS) may be able to confidently assess ST levels with the wearable device in times when a standard ECG is not made available.

Led by Dr. Ciro Indolfi, investigators from the University of Catanzaro in Italy conducted an assessment of the ECG available with the commercial Smart Watch Series 4 device from Apple. As they noted, this smartwatch introduced an integrated ECG tool which can record a single-lead ECG for detecting atrial fibrillation.

“Smartwatches are increasingly popular and used for digital health information,” they wrote. “The aim of the present study was to prospectively investigate the feasibility and the accuracy of the Apple Watch in patients admitted in the CCU with the diagnosis of Acute Coronary Syndrome compared with a standard 12-lead ECG.”

Indolfi and colleagues positioned the posterior sensor of the smartwatch in different standardized body positions to obtain 9 bipolar ECGs from wearers, which were then compared with 12-lead ECGs obtained simultaneously with a standard device.

Their assessment included 100 participants—55 of whom had a ST-elevation myocardial infarction (STEMI), and 27 had a non-ST-elevation myocardial infarction (NSTEMI) all treated with percutaneous coronary revascularization. The remaining 18 age-matched participants served as controls.

Investigators observed a “very good agreement” between smartwatch and standard ECGs for the identification of normal ECG (Cohen’s kappa, 0.90; 95% CI, 0.78 - 1.0), ST segment elevation (0.88; 95% CI, 0.78 – 0.97), and non-ST-elevation alterations (0.85; 95% CI, 0.74 – 0.96).

Sensitivity and specificity of the smartwatch ECG in diagnosing normal ECG were 84% (95% CI, 60 – 97) and 100% (95% CI, 95 – 100). STE deviation were 93% (95% CI, 82 – 99) and 95% (95% CI, 85 – 99), and NTSE ECG alterations were 94% (95% CI, 81 – 99) and 92% (95% CI, 83 – 97), respectively.

Among each lead, investigators observed no significant differences between smartwatch and standard ECGs for the amplitude of ST changes.

In an ESC 2020 session precluding the release of this data, Emma Svennberg, MD, PhD, of the Karolinska University Hospital in Sweden, discussed the viability and dependability of emerging smartwatch ECG devices for cardiac-risk screening.

“I think that possibly we can see that digital health can provide at least some links in the chain toward the solution,” Svennberg said.

Indeed, Indolfi and colleagues found the consumer-friendly smartwatch ECG to have a level of reliability.

“The SMARTAMI Trial demonstrated a very good agreement between the Smartwatch ECG and Standard ECG for the identification of ST-segment elevation and ST depression in patients with acute coronary syndromes opening the possibility of using this tool when a standard ECG is not available,” investigators concluded.

The study, “Multichannel electrocardiograms obtained by a smartwatch for the diagnosis of acute coronary syndromes: the SMARTAMI TRIAL,” was presented at ESC 2020.