Exercise stress testing is very safe. It is always done by well-trained doctors or other professionals. There's a slight risk that this test could bring on a heart attack or a dangerous irregular heartbeat. But this is very rare. Because of this risk, there are guidelines for doctors saying who shouldn't have a stress test.  
Your doctor might do an echocardiogram (see below) while you have an exercise test.Non-exercise stress test
If you can't exercise or you have an abnormal ECG while you are resting, your doctor might suggest you have a non-exercise stress test instead. This test doesn't involve any exercise.
For this test, your doctor can give you a drug to make your heart work harder. And he or she may also use an echocardiogram (see below) or a special scan, called a nuclear scan, to see how your heart is working. (During a nuclear scan, radioactive chemicals are injected into your blood. The chemicals stick to red blood cells and travel through your bloodstream and heart. Doctors can then use a special scanner see images of your heart and blood vessels.)Echocardiogram
An echocardiogram uses sound waves to tell doctors how well your heart is working. It's a type of ultrasound test.
For this test, an instrument that sends and picks up sound signals is put on your chest. The sounds (echoes) it picks up show up on a screen as a picture.
This test is safe and it doesn't hurt.
From this test, your doctor can tell:
How well your heart chambers fill with blood and pump it to the rest of your body
If your heart muscle has any damage
If your heart is a normal size
If your heart valves are working properly.
Coronary angiography is a type of x-ray that shows your coronary arteries.
This test is done in an x-ray laboratory. You may hear doctors call it the cath lab. Before the test, you may be given medicine to make you sleepy.
When you have angiography, doctors put a thin tube (called a catheter) through an artery in your arm or thigh and into your heart. Then they inject dye through the tube into your coronary arteries. When they take the x-ray, the dye shows up.
From this test, your doctor can tell how badly your coronary arteries are narrowed. If it shows that your arteries are very narrow, your doctor may suggest you have a procedure to widen them. This is called coronary angioplasty.