Computer method and apparatus for reading and analyzing ECG signals includes applying a plurality of heart condition detectors to a subject ECG signal. Each detector produces a respective indication of likelihood of certain heart conditions existing in the subject. A lattice having annotations of the different detector heart conditions is formed from the detector indications. The lattice enables medical personnel to navigate through and hence more easily read the ECG signal data. The lattice effectively provides an indexed or annotated version of the subject ECG signal.