How do you know if you're having a heart attack if you have no pain and just have elevated hr?

Elevated heart rate : Tachycardia can heralds a heart attack as a lone symptom, but is rare. Usually shortness of breath, confusion, fatigue, nausea, dizziness, weakness, sweats, or other symptoms accompany it. Rapid heart rate is more likely to mean one of several other diagnosis if encountered alone (hyperthyroid, infection, atrial fibrillation, anxiety, etc). If you have a rapid heart rate, get seen in an er today.