Inclusion Criteria:  - Adult subjects with or without known cardiac disease who are either inpatients or outpatients with ECGs and an echocardiogram within 30-days of the ECG date.  Exclusion Criteria:  No research authorization provided An ECG signal shorter than 10 seconds or that is not interpretable An echocardiogram is considered technically challenging Only qualitative interpretation of left ventricular systolic function available (i.e., "decreased EF") without a numerical value. A paced rhythm