Inappropriate Sinus Tachycardia (IST) is a condition where the heart beats too fast, even when you're at rest. This trial aims to test a new procedure called "hybrid sinus node sparing ablation" to help people with IST who haven't had success with medications.

Eligibility: To participate, you must be between 18 and 75 years old, have a confirmed IST diagnosis, and have tried medications like beta-blockers without success. You will need to sign a consent form.

Exclusions: You cannot join if you've had heart surgery before, have certain heart devices, are pregnant, or have conditions like severe asthma or congenital heart disease.

• The study involves medical procedures and follow-up visits for safety and effectiveness checks.
• You should be able to attend follow-up visits as scheduled.
• The trial is not for people already in other clinical studies.