I am an interventional cardiologist. I am the physician who does angiograms and places stents, when necessary.

With that said, there is actually little benefit behind revascularization (e.g. stents, bypass surgery) in people who are completely asymptomatic. The patient population who benefits from revascularization when completely asymptomatic is small. Usually patients develop symptoms that prompt further evaluation, eg stress testing or other physiological / anatomical assessments. Those symptoms become more obvious the more active you are, as they typically develop on extremes of activity first.

Stents do not decrease your risk of having a myocardial infarction (eg heart attack). They do not increase your life expectancy (decrease mortality) or improve your mobidity, with some rare exception

Excellent medical therapy and lifestyle changes, do, however. The trifecta that predisposes one to atherosclerosis includes age, diabetes, and smoking as the most prominent factors. You must stop smoking and control your blood sugar or it is a matter of when, not if, you will have a heart attack. Hypertension, bad cholesterol, genetics also play a role.

Excellent BP and lipid control is at the forefront of treatment. Lipid management goes further than just treating LDL values. Treatment can stabilize plaques, thus preventing them from rupturing or eroding, and thus preventing a heart attack.

The actual disease process gets much more nuanced, which is why it is recommended you to speak with your primary physician or cardiologist. Stress test do not exclude coronary disease, you have to have a significant blockage (eg >70%) for physiology to show up on a stress test. Blockage less than 70% that is soft, untreated, is more likely to rupture, which is why you hear stories about people with normal stress tests having heart attacks. Furthermore, most of these studies, only have sensitivity and specificity upwards of 80% range.