Heart Palpitations and Muga Vs Echo

[Rupali]

Hi all,
I have been on Herceptin every 3 weeks for more than a year now. Exactly for 14 months.
I was diagnosed with Stage 3A, 9cm tumor, right breast matectomy, dose dense 4AC+ 4 Taxol and 33 rads. COmpleted chemo in May 2005 and have been on Herceptin since.
I also take 400mg COQ10 and a list of other supplements.
I have been relatively ok and have been doing my daily work and also have been actively swimming etc.
Recently in last 2 days I feel some palpitation and feel out of breath.
I called my cardiologist and he said my recent ECHO was good and also my stress echo was fine. He disontinue MUGA 6 months back and said that he will folow me up with Echos every 3 months.
I called him up again to let him know whats going on and he said he would not worry a lot as the ECHO was done a few days back and everything was fine.
I am getting concerned and would like to know what you would have done in this situation.
The other worrysome question is should I go for 2 years of Herceptin or just stop it now and let my heart recover and perhaps start Herceptin again after 2 months or so.

Please advice and comment.
Regards,
Rupali