My hearts been having issues lately, but my cardiologist thought it was due to stress/fatigue.  Passed my stress test, although my heart rate hit target (too) quickly.  My heart is now POUNDING when I go up stairs.  I do have a cold, overweight, 35 female.
Thanks for your question on Chat Doctor. I can understand your concern. Since your stress test is normal, no need to worry about heart diseases for your symptoms. Stress, anxiety can cause heart pounding ongoing upstairs. Another possible cause is obesity. So try to lose some weight and stay fit, healthy. Consult psychiatrist and get done counselling sessions. Try to identify stressor in your life and start working on its solution. You may need anxiolytic Chat Doctor.  Don't worry, you will be alright. Avoid stress and tension, lose some weight. Hope I have solved your query. I will be happy to help you further. Wish you good health. Thanks.