Implantable Medical Device Configured to Store Snapshots of Ectopic Events

A method for operating an implantable medical device for sensing electrocardiogram signals, the method comprising:

• sensing electrocardiogram signals using an arrangement of electrode poles of the implantable medical device;
• and
• processing electrocardiogram signals obtained by the arrangement of electrode poles;
• using a processing module of the implantable medical device;
• wherein the processing module identifies a contraction event based on said electrocardiogram signals,
• classifies said contraction event as an ectopic event based on a relation to other contraction events prior and/or subsequent to said contraction event, and
• stores a snapshot representing data of said electrocardiogram signals in a time period encompassing a contraction event classified as an ectopic event.