Your Heartbeat Signature
Your Heartbeat Signature is a visual profile of how your heart beats during a single Apple Watch ECG recording. It's an ECG+ original feature — the built-in Apple ECG app doesn't produce anything like it.
What the Heartbeat Signature is
ECG+ carefully analyses the electrical waveform captured by your Apple Watch and processes the recording in depth to build a single representative heartbeat shape that reflects the overall pattern of your heart's activity during that recording. Rather than asking you to read a long, jittery strip beat by beat, ECG+ distills it into one clean, characteristic beat — your signature for that moment.
This signature highlights the key parts of the heartbeat — the P wave, the QRS complex, and the T wave — so the rhythm and structure of each beat can be seen far more clearly. (New to these waves? See how to read a PQRST wave.)
The measurements it makes possible
Because the Heartbeat Signature is a clean, representative beat, ECG+ can use it to measure important features of your heartbeat precisely:
- P duration — how long atrial activation takes
- PR interval — the time from the start of the P wave to the QRS
- QRS duration — how long ventricular activation takes
- QT interval and QTc — how long the heart takes to depolarise and recover
Together, these measurements describe how electrical signals move through your heart during each beat — detail the standard Apple result never shows.
Why it's clearer than a raw strip
Natural heartbeats vary slightly from one beat to the next, and small fluctuations and recording noise can make individual beats hard to interpret. The Heartbeat Signature reduces the influence of these small variations, producing a clearer, more stable representation of your heartbeat pattern for the whole recording. The result is a more reliable basis for the measurements above — and an easier picture for you, or your doctor, to read.
A signature for every recording
Each ECG recording produces its own Heartbeat Signature, giving you a simple way to visualise the electrical behaviour of your heart at that moment and to better understand the measurements shown in your report. Over time, comparing signatures is one more way to see how your heart is behaving.
Only in ECG+
The Heartbeat Signature is one of several capabilities ECG+ adds on top of the recording your Apple Watch makes — alongside marking individual PACs and PVCs, calculating premature-beat burden, and more. See the full comparison of Apple Watch ECG vs ECG+, or browse everything ECG+ marks.
