I have a Mitrovalve Prolapse leakage and had a question?

I've been having palpitation's and my doctor diagnosed me with anxiety/ panic attacks and put me on xanax 1mg 3 times a day but they do not help at all. I'm wondering if i should go back to my cardiologist and see if anything is wrong. I was born with this and saw a cardiologist since I was 18 but was told only to come see him unless I had a problem but my regular doctor told me I was just suffering from anxiety/ panic attacks..I am 23 now and can not handle this anymore, any suggestions?