Inclusion Criteria:  Subject is age>=18 years Subject has been scheduled by physician to undergo or has undergone hybrid sinus node ablation procedure using the AtriCure Isolator® Synergy™ device or future iterations of that device for IST or POTS 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:  Subject is enrolled in a concurrent study that has not been approved for concurrent enrollment by the global study manager Subject with exclusion criteria required by FDA or local governance