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Inappropriate Sinus Tachycardia (IST)

What is IST?

Sinus tachycardia is a normal response of the body. It’s when the heart rate becomes elevated and can be in response to such things as physical activity or emotional excitement. 

Inappropriate Sinus Tachycardia (IST) is when the heart rate is elevated at rest or becomes extremely elevated with minimal activity. In general, the heart rate is elevated greater than 100 beats per minute at rest or if monitored over 24 hours have an average heart rate greater than 90 beats per minute.

What are the symptoms of IST?

The main symptom is a faster pulse without any stimulation like physical activity or emotional excitement. In adults, it’s typically over 100 beats per minute. Other symptoms can include headaches, dizziness, chest pains or difficulty exercising. Some people, however, are asymptomatic or don’t have any symptoms.

What are the risk factors of IST?

IST seems to affect more women than men and at a younger age. Some patients have described having a viral illness prior to developing IST symptoms. Other triggers can include caffeine, anxiety, alcohol or nicotine.

How is IST diagnosed?

After reviewing your health history and ruling out other causes of a fast heartbeat, a patient will have an electrocardiogram (ECG) to monitor their heart rate and then will wear a heart monitor for 24 hours.

What are IST treatment options?

Treatment options vary but can include medications or eliminating potential triggers or stimulants in your diet such as caffeine, nicotine and alcohol. Other treatments can include  a catheter ablation or a hybrid catheter ablation.

Learn More About our Cardiac Arrhythmia Program

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