Hi ! Thank you for using HCM I would say that having only difficult breathing during walking or taking the stairs is not enough to say that you have heart problem . Usually i would say that a patient has heart problem When he /she experience chest pain ( is the main symptom) with shortness of breath , sweating ,severe weakness, fainting . The pain is like a pressure in your chest, sharp, tightness or squeezing . The symptoms your describe are more due to Asthma. I would advise you to check the the drug dosage and to check your heart to be sure by asking an appointment with your doctor . Wish you good health. If you have any question please feel free to ask me .