What could be the cause of heart pain and frequent urination?

2 things: They most likely are unrelated. Heart pain, i guess meaning pain in the chest, could be related to something other than the heart. If it is heart related there are several possible reasons (blocked artery, pericarditis for instance). I cannot think of a way to relate any of them to frequent urination. For that think of diabetes or infection in the kidney or bladder.

Diabetes link: Diabetes mellitus can cause frequent urination if untreated and increase the risk for a heart attack. Do you have other risk factors for cardiovascular disease? Family history, high ldl, smoking, htn, obesity, sedentary lifestyle, high alcohol intake? Check with your physician for a complete history and physical.