Multichannel Electrocardiograms Obtained by a Smartwatch for the Diagnosis of ST-Segment Changes

Abstract

Importance: Acute coronary syndromes are the leading cause of death worldwide and the leading cause of disease burden in high-income countries. Quick and accurate diagnosis of acute coronary syndromes is essential to avoid fatal events, for timely intervention, and to improve the prognosis.

Objective: To prospectively investigate the feasibility and accuracy of a smartwatch in recording multiple electrocardiographic (ECG) leads and detecting ST-segment changes associated with acute coronary syndromes compared with a standard 12-lead ECG.

Design, setting, and participants: A commercially available smartwatch was used in 100 participants to obtain multiple-channel ECGs. The study was conducted from April 19, 2019, to January 23, 2020. Fifty-four patients with ST elevation myocardial infarction, 27 patients with non-ST elevation myocardial infarction, and 19 healthy individuals were included in the study. The watch was placed in different body positions to obtain 9 bipolar ECG tracings (corresponding to Einthoven leads I, II, and III and precordial leads V1-V6) that were compared with a simultaneous standard 12-lead ECG.

Main outcomes and measures: The concordance among the results of the smartwatch and standard ECG recordings was assessed using the Cohen κ coefficient and Bland-Altman analysis.

Results: Of the 100 participants in the study, 67 were men (67%); mean (SD) age was 61 (16) years. Agreement was found between the smartwatch and standard ECG for the identification of a normal ECG (Cohen κ coefficient, 0.90; 95% CI, 0.78-1.00), ST-segment elevation changes (Cohen κ coefficient, 0.88; 95% CI, 0.78-0.97), and non-ST-segment elevation changes (Cohen κ coefficient, 0.85; 95% CI, 0.74-0.96). In addition, the Bland-Altman analysis demonstrated agreement between the smartwatch and standard ECG to detect the amplitude of ST-segment changes (bias, -0.003; SD, 0.18; lower limit, -0.36; and upper limit, 0.36). Use of the smartwatch ECG for the diagnosis of normal ECG showed a sensitivity of 84% (95% CI, 60%-97%) and specificity of 100% (95% CI, 95%-100%); for ST elevation, sensitivity was 93% (95% CI, 82%-99%) and specificity was 95% (95% CI, 85%-99%); and for NSTE ECG alterations, sensitivity was 94% (95% CI, 81%-99%) and specificity was 92% (95% CI, 83%-97%).

Conclusions and relevance: The findings of this study suggest agreement between the multichannel smartwatch ECG and standard ECG for the identification of ST-segment changes in patients with acute coronary syndromes.

Conflict of interest statement

Conflict of Interest Disclosures: None reported.

Figures

Figure 1.. The Positions of the Smartwatch to Obtain 9-Lead Electrocardiograms (ECGs)

The multiple-lead ECG with the smartwatch was obtained as follows: lead I was recorded without the removal of the smartwatch on the left wrist using the right index finger on the crown. The recording of other leads required the removal of the watch and proper placement at appropriate abdomen and chest locations. Lead II was obtained with the watch on the left lower abdomen and the right index finger on the crown, and lead III was obtained with the watch on the left lower abdomen and the left index finger on the crown. The chest leads were recorded corresponding to the location of V1 (fourth intercostal space right parasternal), V2 (fourth intercostal space left parasternal), V3 (between V2 and V4), V4 (lead at the fifth intercostal space midclavicular line), V5 (lead at the fifth intercostal space anterior axillary line), and V6 (lead at the fifth intercostal space midaxillary line).

Figure 2.. Comparison of the Amplitude of ST-Segment Deviations Between Smartwatch and Standard Electrocardiogram (ECG)

Bland-Altman plot indicating the level of agreement between the smartwatch ECG and standard ECG measurement of ST-segment deviations. The black line represents the bias (mean difference), and the dashed lines represent the upper and the lower limits of agreement (bias and 1.96 SD). This difference is considered clinically nonsignificant.