Inappropriate Sinus Tachycardia Registry

Inclusion Criteria: 1. Subject is scheduled to undergo or has undergone a procedure to treat IST or POTS using one or more AtriCure devices. 2. Subject is willing to provide written informed consent (defined as legally effective, documented confirmation of a subject's voluntary agreement to participate in this Registry) or authorization per institution and geographical requirements Exclusion Criteria: 1. Subject is enrolled in a concurrent study that may impact treatment outcome of IST or POTS. 2. Subject with exclusion criteria required by FDA or local governance