If you see a cardiologist, they will be able to determine if this is a result of heart disease and if you are at risk for a future heart attack. Blood tests will reveal if one is happening now, which is possible because symptoms vary. Some people feel no discomfort and have no idea they had a heart attack, while others are brought to their knees in agony. If blood tests reveal no attack, then they can test for angina by a stress test as Flycaster points out. An echo is next to useless for Angina if you only get symptoms on exertion, but it can reveal plenty of other situations such as leaky valves or enlargement. If they try to tell you that angina is always associated with exertion, then tell them it isn't. Angina can be triggered by a few things, even air temperature. I had to walk for about 20 mins to trigger my angina, and get my heart to around 140 bpm, but if I opened the front door on a cold day, it instantly hit me. If you feel it could be the heart, it's always worth getting checked out just in case. Too many people don't bother and end up with damaged heart muscle for the rest of their lives.
I'm sorry for your diagnosis, and I'm sure it can mask other problems. However, most hospitals have labs that can determine from your blood sample what is happening, and a couple of basic tests, an Echocardiogram and a stress test that can narrow down any potential reasons for heart problems, if your symptoms are heart related, and if your hospital can't provide these services, I'm sure they will refer you to the closest facility that can help you.
I hope you keep us informed.