Methods and systems provide an integrated approach to respiratory and cardiac monitoring, diagnosis and/or therapy. A medical system includes one or more cardiac electrodes coupled to an external respiratory therapy device. The cardiac electrodes sense cardiac electrical activity that is used to generate an electrocardiogram (ECG) signal. Cardiac events, such as arrhythmia, myocardial infarction and/or ischemia, may be detected based on the sensed cardiac electrical activity.