Thank you for posting your query on XXXXXXX
Well looking into your problem I would like to tell you that since you suffer from scleroderma
a possibilty of heart involvement cannot be ruled out .
What your doctor have told you is right because they are thinking this to be sinus bradycardia
but I would strongly recommend a 2 D ECHO to rule out any cardiac involvement including pericardial effusion
which can also lead to such symptoms . I think you should consult your cardiologist and get it done as early as possible .