THe only sure fire way to check your heart is to have them pump some fluid in that allows them to see your heart and arteries pumping real time on a screen. A catheter operation in the cath lab. This can be expensive though I have heard there is a good deal in CHicago for a few hundred dollars. The rest, i.e., ECG is not a guarantee of diagnosis, I had several before my infarction as routine check ups and none revealed a 90 percent clogged LAD (Widow maker) and similarly clogged RCA and 50 percent clogged circumflex (which they didn't stent yet because stent cut off line is %70). Perhaps a stress test with the ECG is better. But taking a live camera look is the way to go if you really want to know, you can go in in the morning and be out by the afternoon if all goes well.
This procedure is called Angiography and I had this done for my dad after he was suffering with lack of stamina and heavy breathing even with mild exertion. The doctors found 5 blockages which wasn't surprising since he used to be a smoker and a foodie. Multiple stents were put (couple of blockages were so bad that the couple of wires used to make way for the stent bent and couldn't penetrate but thankfully they were not in the bigger arteries).
I've resolved to undergo Angiography, symptoms or not, once I turn forty. Angiography is not cheap but it is way more cheaper considering the costs of stents (specifically the ones that dissolve are quite expensive). A day of preparation and an hour of discomfort is nothing at all considering the benefits.
I agree, something to think about, but the very first hit on Google for "elective angiography" was an article discussing whether it is over-used due to the dangers including significant radiation. :/
