Patent ID: 7715916

Claim:
An arrhythmia discrimination method, comprising: sensing electrocardiogram signals at a subcutaneous non-intrathoracic location; receiving signals associated with a non-electrophysiological cardiac source, the received signals varying in relation to cardiac activity; verifying that the electrocardiogram signals comprise a cardiac signal using the received signals; discriminating, using the electrocardiogram signals and received signals, between a normal sinus rhythm and a cardiac arrhythmia, wherein discriminating between the normal sinus rhythm and the arrhythmia comprises: detecting the arrhythmia using the electrocardiogram signals; determining temporal relationships between the electrocardiogram signals and the received signals while detecting the arrhythmia; and verifying presence of the arrhythmia based on the temporal relationships between the electrocardiogram signals and received signals; and withholding delivery of subcutaneous non-intrathoracic cardiac stimulation therapy if the sensed electrocardiogram signals do not comprise the cardiac signal.