A leadless wireless ECG measurement system for measuring of bio-potential electrical activity of the heart in a patients body (12) includes at least one multi-contact bio-potential electrode assembly (20) adapted for attachment to the patients body (12). The electrode assembly (20) is formed of an electronic patch layer and a disposable electrode layer. The disposable electrode layer has a plurality of contact points for engagement with the surface of the patients body (12) and is configured to measure short-lead ECG signals in response to electrical activity in the heart. A processing unit is provided and is configured to produce a transfer function which computes estimated long-lead ECG signals based on the measured short-lead ECG signals from the plurality of contact points.
