I spoke to Dr. Aaron Abraham, an intensive care physician who ran a children's ward in Bombay for seventeen years, and who now works in Israel, and he knows of no such title.

I googled kardiolog metapel (in Hebrew) in Google, and I came up with nothing (apart from the reference to your proz.com query). That tells me that there is no fixed expression or title "kardilog metapel".

That takes me back to "attending cardiologist".

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Note added at 2 days14 hrs (2016-06-24 12:54:36 GMT)
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Based on Michael's answer to me, I would translate kardiolog metapel as "the patient's cardiologist". The reader will understand by himself that this cardiologist was referred to the patient by the patient's primary care giver, and that he may or may not be someone who the patient goes to a lot.
Raphael