Ask the doctor: Understanding conflicting test results

Q. The results of my recent stress test indicated I may have blockages in my coronary arteries. However, when I followed up with a cardiac catheterization, my arteries looked clear. How can that be?

A. A stress test is an excellent first step when looking for heart disease. It is especially useful in people who have chest pain with activity, unexplained breathlessness, or other cardiovascular symptoms. However, no medical test is 100% accurate, and noninvasive stress tests can err in either a false negative or false positive direction.