My son was diagnosed with tachycardia. Is it serious?

My son is 13 year old, and he was diagnosed with tachycardia. Is this serious? His doctor says that he doesn't need to be treated for it.

It depends on how fast the heart rate is and if he is symptomatic.

Tachycardia is a very broad term. Some are benign and don’t need treatment. We need to know what kind of tachycardia.