Hello and thank you for using HCM.I carefully read your question and I understand your concern.But dont worry.I ll try to explain you something and give you some advises. You might experience fast and strong heart beats for different reasons. It may be a simple sinus tachycardia.This mean that your heart beats over 100 beat for minute.Its normal range in resting situation is between 60-100 beat for minute.This might happen from different reasons from simple emotional stres to different pathologys like anamia,hyperthyroidism ect. You may feel strong heart beats because of extrasistoles.This are electrical impulses that generates from different parts of the heart different from that of a normal sinus rhythm.This couses an ectopic, escaped beat and you feel like a beat is skipping and the other one is stronger causing difficulties in breathing fully and sometimes a cough. The extrasistolic beats might happen for the same reasons as sinus tachycardia.Sometimes in young ages or in stressed periods this are quite normal and they come ang go. But if your heart beats very fast sundenly and in a chaotic,irregular way it might be what we call an atrial fibrilation.This is an ariithmia when the heart doesn t beat in a normal sinus rhythm.You might experience paroxysmal episodes when your heart jumps from normal rhithm to fibrilation and vise- versa. So, if I was your treating doctor I will recommend you to make some simple examinations like a blood analysis to exclude anemia or hypothyroidism, a electrocardiogram,echo cardiography and of course a holter monitoring for 24-48 hours.this will tell as your rhythm tendency. You have nothing to worry but I will recommend this chek up if this symptoms begin to interfere with your normal healthy live. At mean time avoid coffee and caffeine products becouse they rise your heart frequency or exstra systoles. Hope I was helpful.Wish you good health.Best regards.