i had undergone stenting 4 times, just because i had the pulpitation. its not difficult for me to do exercises and i dont get tired, but i get pulpitation,chest pain and shortning of breath sometimes when i lie down to sleep.The last holtermeter test showed that a heart beat is missing, my cardiologist told me that there is nothing to worry about. i keep wondering that is it from the medicines those that i am taking.