The Reveal LINQ Usability Study is a prospective, non-blinded, non-randomized, multi-center clinical trial. Subjects will transmit device data via manual interrogation on a weekly basis during the first month and will be evaluated in the office at 1-month post-implant, in addition to an automatic nightly wireless data transmission using the MyCareLink® home monitor. All subjects will be requested to wear an external Holter for 48 hours at approximately 4 weeks post-insertion. Follow-up visits will continue at 6 and 12 months post-implant, with monthly manual interrogations. Subjects will be exited at their 12 month follow-up visit. The overall study will be conducted in 2 phases which differ primarily on inclusion criteria: Phase I subjects (initial 30 subjects) will have any indication for an ICM, Phase II subjects (all subjects following the initial 30 subjects) will be atrial fibrillation (AF) pre-ablation patients. The study will assess functionality of the Reveal LINQ device by assessing sensing performance and data transmission.