Being a smoker and having high cholesterol puts you at an intermediate to even high risk of having CAD. I would recommend the stress testing. Given that you are on the slightly higher risk side, a catheterization would not be unreasonable.
I smoke, family members on my mom side have arrythmias. My cholesterols are high, but they did not put me on any meds for it, they just told me to adjust my diet and lower my salt intake. I have done all they have told me to do...
What is your age and what are your risk factors for CAD (smoking, DM, HTN, family history, cholesterol). These factors give us a general risk of coronary artery disease and guide out further diagnostic evaluation. Unfortunately, the monitor or the echo don't really help in terms of ruling out coronary artery disease as the cause of your pain. Because the symptoms do sound concerning for coronary artery disease, your doctors should probably consider further testing such as a stress test. You may also need a monitor that is worn for a couple of weeks to see whether or not there is some sort of tachycardia that could also explain your symptoms.