Abstract: An ECG device may include a housing, a plurality of leads coupled with the housing, and couplers configured to attach the leads to electrodes. A marking switch may be coupled with the housing. The ECG device may be configured to monitor cardiac-related activity and record related data. The marking switch may be configured to record a heart-related event when engaged by a user. User interfaces on one or more computing devices may allow a clinician and/or a patient to view information related to the ECG device and its recorded data, as well as to facilitate communication between the ECG device and one or more servers and to associate symptoms with heart-related events. ECG systems include the ECG device and the one or more servers. ECG methods involve using the ECG device and ECG system in recording and storing heart-related data and allowing clinicians access to retrieve it for analysis.