Thank you for your query at DoctorSpring.com.
I understand your concern. Since your work-up for heart related issues is all clean, there is no reason to suspect any heart disease. If you do not have symptoms such as chest pain, shortness of breath on minimal exertion, fainting spells and if your EKG and ECHO and perhaps Holter monitoring are all normal, then heart disease can be ruled out firmly.
I am of the opinion that your symptoms of pounding heart accompanied by sweating are anxiety related. I suggest that youconsult your doctor, a psychiatrist perhaps, for dose adjustment or change of medications so that your symptoms can be taken care of. In addition, you should undergo cognitive behavioral therapy which is highly beneficial in anxiety disorders such as your panic attacks.
I hope this was helpful.
Feel free to ask queries.