dear friend
i hope the ECG showed
SINUS TACHYCARDIA only, if that is the case, then in all probability you have only a reactionary increase in
heart rate. As you have mentioned that you encounter stress in life and the palpitations are associated with stress, the most likely explanation for this tachycardia is stress only. you must try
relaxation techniques and take help of a
psychologist, if needed. your normal ECHO is reassuring.
other causes of tachycardia can be excessive intake of coffee, tea,. smoking, anxious personality trait, drugs for common cold/asthma, fever, anemia and
hyperthyroidism (which is ruled out in your case).
one more help is that if your pulse rate is normal at times when you are not under stress, like sleeping, then, again it favours a reactionary increase in heart rate. (
hope this answers your query, thanks for writing to us.
sincerely