Upstairs can indicate either your spiritual side or your intellect. Look for other symbols that indicate Spirituality in the same dream.
When a dream has a lot of symbols for the heart, the upstairs is often about the intellect. It is very common for dreams to show the cost on your heart because you rationalize all the time (operating from your head).
Walking upstairs can be about activating your spiritual side or your intellect. Again to tell which, you need to look at the other symbols in the same dream.
