Guidelines may vary, but generally, heart rates greater than 120 to 150 beats per minute can be dangerous. When the heart rate is that high, a person with AFib should consider seeking medical attention, especially if there are other symptoms present.

Once a person’s heart rate consistently exceeds 120 beats per minute, they are at a risk of hemodynamic instability. This means that the heart cannot properly deliver blood to all of the parts of the body that it needs to. Hemodynamic instability needs to be addressed in order to allow blood flow to be resumed.

When someone has AFib, it means they have an irregular heart rate. Some people with AFib experience no symptoms, while others often report having a fast heart rate. In AFib, unusual electrical signals in the atria or upper chambers of the heart disrupt how fast the heart beats.

The typical heart rate for a person when they are resting is between 60 to 100 beats per minute. A heart rate that is very high or consistently high can be concerning in AFib. It can lead to serious health complications and put a strain on the heart.

A few factors can influence what is considered a dangerously high heart rate in a person with AFib. These include:

  • whether the person is resting or exercising
  • whether the person has other health conditions
  • the person’s overall health

People with AFib can work with their doctor to determine what heart rate is too high on an individual basis and when to seek help.

Generally, though, a person with AFib should consider seeking emergency help if their heart rate is above 120 beats per minute and they have the following symptoms:

A healthcare professional can recommend the best course of treatment to manage and lower the heart rate. It might include medications or other interventions.