What can a doctor tell me about my risk for fast heart rate?

Not sure...: Heart rate itself, when in normal rhythm, is highly variable and depends on many factors. When abnormal rhythm develops such as atrial fibrillation or flutter, fast heart rates are usually avoided with medications or other therapy. If you have some types of valvular heart disease you might be at higher risk for atrial fibrillation, and also if your left atrium is large on echo.