I found this on a web md site. Hope it helps you better understand things. Don't know what trouble you were having but they were likely checking to make sure all was ok based on your symptoms at the time.
"cardiac enzyme studies measure the levels of the enzymes troponin (tni, tnt) and creatine phosphokinase (cpk, ck) in the blood. Low levels of these enzymes are normally found in your blood, but if your heart muscle is injured, such as from a heart attack, the enzymes leak out of damaged heart muscle cells and their levels in the bloodstream rise.
Because some of these enzymes are also found in other body tissues, their levels in the blood may rise when those other tissues are damaged. Cardiac enzyme studies must always be compared with your symptoms, your physical examination findings, and electrocardiogram (ekg, ecg) results."