A system for performing an electrocardiogram (ECG) can include a handheld electrocardiograph device having a right arm electrode, a left arm electrode, and a left leg electrode, and can be configured to receive signals from the electrodes and to send data based on the electrode signals to a mobile electronic device. The mobile electronic device can be configured to process and analyze the receive information to provide ECG data, such as 6-lead ECG data. The mobile electronic device can analyze the ECG data to provide diagnostic information. The mobile electronic device can transfer the ECG data to a remote computing system, which can analyze the ECG data to provide diagnostic information.