The Northern Ireland international has gone off with a leg knock in each of his last two matches, for club and country.
Hearts coach Gordon Forrest said: "We are assessing Mikey, he is back in, but off the pitch. We will see how he is on Friday and make that decision. He is an important player for us and we have got to look after him."
Smith was replaced by Taylor Moore, a recent loan signing from Bristol City, during Sunday's goalless Edinburgh derby and Forrest is pleased with the depth that manager Robbie Neilson has available.
"With the additions to the already good group we have got, it now provides good options for us for the starting XI to coming off the bench, but not only that, it gives us good training sessions, good competition," he said.
"We have a good group of players, they understand it's going to take the squad to achieve what we want to try to achieve this season.
"So you can see they are sticking together just now, they are helping each other out. They know they will get their opportunities and when they do get their opportunities, they will produce for us.
"But we need that full squad. At the moment the boys are in a good place, supporting each other."