Hello Aliasaskar,
if you want to train on cardiology the others are right - first of all you have to get your qualifications recognized. I've done a little research for you via anabin.de - looking at this, if you have an Egyptian M.D. it is equivalent to the German Dr med. To get your licensure however, you have to apply to the LPA (Landesprüfungsamt) of the Federal State you want to live in (you are allowed to work anywhere in Germany with this licensure - it just depends on the place where you live at the beginning of your career in Germany). I think profiency in German is absolutely necessary - the others' information is correct.
Afterwards you can apply for residency/specialty training in hospital. It's not part of college/university here. For cardiology for example you have to choose the specialty internal medicine (5 years) and at the end of these years you can specialise on cardiology (but have to go through the other internal disciplines as well). There are some hospitals which are well known for a very good cardiology - maybe such a placement might be appropriate for you.
If you have any questions concerning the application, don't hesitate to ask - I am a native speaker in German by the way