The Apple Watch ECG proved capable of detecting an irregular heartbeat as accurately as a hospital’s medical-grade equipment, according to a first-hand account of a side-by-side test carried out when the feature first arrived.
The turning point came in 2018 with the debut of the Apple Watch Series 4, the first model to offer electrocardiogram functionality. Sceptical that such a small sensor could rival the wires, stickers and monitors of hospital electrocardiograms, the writer set out to compare the Series 4’s ECG against a hospital unit. As a healthy, active 30-year-old, they did not expect to become part of the story.
How the Apple Watch ECG works
An electrocardiogram measures the heart’s electrical signals and requires a complete electrical circuit. The Apple Watch closes that circuit using two electrodes: one on the back of the case, resting against the wrist, and one on the Digital Crown, touched by a finger. That arrangement provides a single lead, compared with the 12 used by a hospital. Fewer leads mean less detail, but comparable accuracy.
During the test, the Apple Watch showed the same pattern as the hospital ECG and flagged an irregular heartbeat. The cardiologist paused to review the results. After further testing, that early beat proved benign, most likely the result of stress and sleep deprivation linked to juggling a new baby and a full-time job.
From novelty to health tool
The experience shifted the writer’s view of the device from a vanity-metric gadget to a tool capable of catching something in the heart before it could be felt. Years later, they gave their parents Apple Watches as a form of insurance for fall detection and heart-health alerts. Last year, their father’s watch flagged an issue that ultimately led to his diagnosis and treatment for a potentially life-threatening heart condition.
Similar Apple Watch health accounts have since become common, with more expected as the technology spreads. The original article and video now read as a snapshot of the moment the writer’s relationship with the device changed. The ECG feature has remained a core part of the Apple Watch line, appearing on models through to the current generation.
