walking down stairs  and  heart beating so fast could not count it-- felt like  in my throat and upper chest NO history of high  BP  it converted back to normal rhythm in about 3 to five minutes  is this a panic attack or heart disease  iam a 60 year old healthy female--- only risk factor is over weight BMI 29-30
Mostly your body is not used to exercise, hence the heart rate Response is higher, however if persistent, associated with chest heaviness Or breathlessness, get a stress test done Regards Chat Doctor.