A study physician who has undergone specific training will insert the Medtronic Reveal LINQ ICM according to manufacturer instructions in the CRC. The device will be inserted on day 1. Briefly, using sterile technique and local anesthesia, a very small (6 to 8 mm) skin incision is made over the left chest. The ICM, which is approximately cylindrical and measures roughly 2 cm long and 5 mm in diameter, is inserted using a proprietary insertion tool and a sterile dressing is applied at the end of the procedure. The device will be programmed to optimize the memory for storing AF episodes. "AF-only mode" will be activated and programmed to "All episodes" to ensure that the shortest possible AF episodes are detected and stored in the device memory. The patients will be taught how to perform a CareLink transmission using the small handheld "Patient Assistant" device. Medtronic personnel will be on hand to aid in the insertion and initial programing of the ICM as well as patient education with the Patient Assistant device.