Double bipolar configuration for atrial fibrillation annotation

A computer implemented method of determining quality of an annotation comprising:

• receiving an electrogram;
• detecting a plurality of QRS episodes in the electrogram and generating a mean QRS signal from the QRS episodes;
• subtracting the mean QRS signal from the plurality of QRS episodes detected in the electrogram to generate an adjusted electrogram in which potential annotations are exposed;
• identifying an annotation from the adjusted electrogram;
• estimating a quality of the annotation based on one or more parameters selected from:
• an amount and type of filtering required to determine the annotation;
• a position of a unipolar electrode generating its signal;
• a location in the heart from where a signal was acquired;
• a timing of the annotation;
• or
• whether the annotation is at or close to a time where a signal adjustment has been made;
• and
• assigning a value to the quality based on the one or more parameters;
• wherein the numerical value of the quality may be upgraded or downgraded based on the likelihood that the one or more parameters indicates an annotation.