What is the clinical evidence from this study?

Study design: Observational. Population: Atrial fibrillation (n=74). Intervention: Apple Watch single-lead ECG vs. 12-lead ECG. Primary outcome: Sensitivity to detect atrial fibrillation and specificity to detect sinus rhythm (k = 0.94).

December 1, 2022Cardiovascular Digital Health Journal38 citationsOpen Access

Accuracy and clinical relevance of the single-lead Apple Watch electrocardiogram to identify atrial fibrillation

SPShari Pepplinkhuizen WHWiert F. Hoeksema WSWilleke van der Stuijt

Key Result

The Apple Watch single-lead ECG demonstrated a sensitivity of 93.5% and specificity of 100% for detecting atrial fibrillation on the first measurement, though 27.9% of recordings were initially unclassifiable.

Study Design

Type

Observational (n=74)

Blinding

Single-blind

Multicenter

Structured PICO

Does the single-lead Apple Watch electrocardiogram accurately identify atrial fibrillation compared to a 12-lead ECG in patients scheduled for electrical cardioversion?

Population

74 adult patients (mean age 67.1 years, 20.3% female) with atrial fibrillation scheduled for elective electrical cardioversion.

Intervention

Single-lead electrocardiogram using Apple Watch obtained pre- and post-electrical cardioversion (up to 3 times if unclassified)

Comparator

12-lead electrocardiogram (reference standard)

Outcome

Sensitivity, specificity, and kappa coefficient for identifying atrial fibrillationsurrogate

The Apple Watch single-lead ECG demonstrates high sensitivity and specificity for detecting atrial fibrillation in a clinical setting, though repeated measurements beyond two may reduce accuracy.

Main Result

Effect estimate: k = 0.94

Limitations

Performed in a population with a high prevalence of AF, resulting in a high a priori pretest probability
Low number of female patients included
Age discrepancy between typical wearable users (<50 years) and the at-risk group for ischemic stroke

Abstract

BackgroundThe Apple Watch (AW) is the first commercially available wearable device with built-in electrocardiogram (ECG) electrodes to perform a single-lead ECG to detect atrial fibrillation (AF).MethodsPatients with AF who were scheduled for electrical cardioversion (ECV) were included in this study. The AW ECGs were obtained pre-ECV and post-ECV. In case of an unclassified recording, the AW ECG was obtained up to 3 times. The 12-lead ECG was used as the reference standard. Sensitivity, specificity, and kappa coefficient were calculated.ResultsIn total, 74 patients were included. Mean age was 67.1 ± 12.3 years and 20.3% were female. In total 65 AF and 64 sinus rhythm measurements were obtained. The first measurement with the AW showed a sensitivity of 93.5% and specificity of 100% (κ = 0.94). A second measurement resulted in a sensitivity of 94.6% and specificity of 100% (κ = 0.95). A third measurement resulted in a sensitivity of 93% and a specificity of 96.5% (κ = 0.90). Adjudication of unclassified recordings by a physician reduced the total unclassified recordings from 27.9% to 1.6%, but also reduced the accuracy. The kappa coefficient for unclassified single-lead ECGs was 0.58.ConclusionThe single-lead ECG of the AW shows a high accuracy for identifying AF in a clinical setting. Repeating the recording once decreases the total of unclassified recordings; however, a third recording resulted in a lower accuracy and the occurrence of false-positive measurements. Unclassified results of the AW can be reduced by physicians’ interpretation of the single-lead ECG; however, the interrater agreement is only moderate. The Apple Watch (AW) is the first commercially available wearable device with built-in electrocardiogram (ECG) electrodes to perform a single-lead ECG to detect atrial fibrillation (AF). Patients with AF who were scheduled for electrical cardioversion (ECV) were included in this study. The AW ECGs were obtained pre-ECV and post-ECV. In case of an unclassified recording, the AW ECG was obtained up to 3 times. The 12-lead ECG was used as the reference standard. Sensitivity, specificity, and kappa coefficient were calculated. In total, 74 patients were included. Mean age was 67.1 ± 12.3 years and 20.3% were female. In total 65 AF and 64 sinus rhythm measurements were obtained. The first measurement with the AW showed a sensitivity of 93.5% and specificity of 100% (κ = 0.94). A second measurement resulted in a sensitivity of 94.6% and specificity of 100% (κ = 0.95). A third measurement resulted in a sensitivity of 93% and a specificity of 96.5% (κ = 0.90). Adjudication of unclassified recordings by a physician reduced the total unclassified recordings from 27.9% to 1.6%, but also reduced the accuracy. The kappa coefficient for unclassified single-lead ECGs was 0.58. The single-lead ECG of the AW shows a high accuracy for identifying AF in a clinical setting. Repeating the recording once decreases the total of unclassified recordings; however, a third recording resulted in a lower accuracy and the occurrence of false-positive measurements. Unclassified results of the AW can be reduced by physicians’ interpretation of the single-lead ECG; however, the interrater agreement is only moderate.

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