Inappropriate Sinus Tachycardia

Medically Reviewed by James Beckerman, MD, FACC on February 04, 2022

Sinus tachycardia is when your body sends out electrical signals to make your heart beat faster. Hard exercise, anxiety, certain drugs, or a fever can spark it. When it happens for no clear reason, it’s called inappropriate sinus tachycardia (IST).

Your heart rate might shoot up with just a little movement or stress. Or it might be high when you’re doing nothing. IST is most common in women in their 30s. Symptoms can last for months or years. You might not notice it at first.


Some people don’t have any. But the main symptom is a faster pulse that comes out of nowhere. In adults this means it’s over 100 beats per minute. You might notice that you can get your pulse up to 150 with very little effort. Other symptoms include:

IST usually doesn’t lead to serious long-term health issues. But you should still talk to your doctor if you have any of these symptoms. They could be signs of another health problem.


Doctors don’t fully understand why IST happens. In some cases, nerves might mistakenly send signals to speed up your heart rate. The nerves that lower your heart rate might not work right, either.

A viral infection can lead to IST in some people. In those cases, symptoms sometimes go away suddenly in a few months or years.

These normal fast pulse triggers may cause even higher heart rate spikes in people with inappropriate sinus tachycardia:


Your doctor will ask you about your health history and symptoms. An obvious sign would be a racing heart. But something else may be causing your fast pulse, like certain heart and thyroid conditions or mental health issues like anxiety.

These tests that can help your doctor figure out if it’s IST:

  • Blood tests to check for other fast heartbeat causes
  • An EKG (electrocardiogram) to analyze your heart’s electrical pulses
  • A Holter monitor to track heart activity for 24 hours or more
  • A chest X-ray for pictures of your heart
  • An echocardiogram to check your heart’s size, strength, and ability to pump blood


Your doctor may suggest a “wait and see” approach if your symptoms aren’t causing major problems. Try to avoid triggers like nicotine, alcohol, or caffeine.

Exercise and eating well can help keep your heart strong. They also help with conditions that can make IST worse, like diabetes, high blood pressure, and being overweight.

Your doctor may prescribe drugs like ivabradine, beta-blockers, or calcium channel blockers to help.

Show Sources


American Heart Association: “Ablation for Arrhythmias.”

Arrhythmia Alliance: “Inappropriate Sinus Tachycardia.”

Cedars Sinai: “Inappropriate Sinus Tachycardia.”

Journal of the American College of Cardiology: “Inappropriate Sinus Tachycardia.”

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