I get chest pain or tightness

Chest pain is the single most common reason people are referred to a cardiologist, and most of the time the cause turns out not to be the heart. Working out which case you are in is the point of the assessment.

The details matter more than people expect. What brings it on, whether it eases with rest, how long it lasts, where it spreads and what comes with it all shift the likelihood considerably — often more than any single test does.

From there the question becomes which investigation actually answers it. That might mean looking directly at the coronary arteries with a CT scan, or looking at how the heart behaves under exertion with a stress test.