An echo shows the size and thickness of the heart chambers, how well the heart pumps (ejection fraction), valve narrowing or leakage, blood flow, pressure estimates, fluid around the heart and the width of the aortic root. It is the usual test for breathlessness, a heart murmur, high blood pressure or heart failure.
A normal echo is reassuring about the structure and pumping strength of your heart, but it does not rule out everything. A resting echo does not directly show the coronary arteries, so it cannot on its own confirm or exclude blocked arteries, and it does not record your heart rhythm over time. If your cardiologist thinks you need a stress test, a CT coronary angiogram, an ECG or a Holter monitor, you are told on the day.