Yes, EPICARDIA is a Scrabble word!

Letter values in Scrabble US: E 1, P 3, I 1, C 3, A 1, R 1, D 2, I 1, A 1.

Is it a valid word?

EPICARDIA is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

the short part of the esophagus extending downward from the diaphragm to the stomach
the innermost of the two layers of the pericardium

Also: visceral pericardium.