Inappropriate Sinus Tachycardia (IST) is a condition where the heart beats too fast without a clear reason, making people feel tired and unwell. This study will test a new procedure called hybrid sinus node sparing ablation, which aims to safely and effectively treat IST by targeting the heart's electrical system without removing the sinus node, which controls heart rate. The study focuses on people who can't take medicine for IST or find the medicine doesn't work.

To join, participants must be between 18 and 75 years old and have IST. They can't join if they have certain medical conditions like heart devices or previous heart surgeries.

• The study involves a medical procedure that may have risks like any surgery.
• Participants will need to attend follow-up visits to monitor their health.
• It's important to consider personal health conditions and discuss with a doctor before participating.

Note: This study is not for those who are pregnant, have certain heart diseases, or are unable to attend scheduled visits.