One-week follow-up visit: All patients will return for a brief visit in the CRC 1 week after ICM insertion for a wound check and to obtain a 12-lead ECG. A study physician will perform a brief focused history to assess medication tolerance and compliance. A pill count will be performed to further assess compliance. Barring any ECG abnormalities or clinical side effects, patients initiating flecainide will be instructed to increase the dose to the final dose of 150 mg twice daily.