For a few months now, my heart has been racing and for no apparent reason. I went to the ER last month 3 times thinking I was having a heart attack. These "attacks" mainly only happen at night. I've had 2 EKG's and an echocardiogram. EKG's were normal and my echo showed very mild mitral valve prolapse. My doc said that he had reviewed my echo 3 or 4 times and he was sure that it wasn't the mitral valve causing these symptoms. He said that I was having anxiety attacks but I don't have an attack that will happen and go away in 30 min. or so, but a feeling of nervousness and rapid heartbeat will come and go many times throughout the day. At night is when my heart goes crazy and feels like its beating out of my chest. Also, lately I've had this constant pressure in my chest and had shortness of breath. When my heart does slow down, the slightest movements sends my heart racing again. Is this truly anxiety or is there an underlying heart condition??