Some people with chest pain are found to have open arteries on angiograms instead of blocked arteries and many, but not all, of these people have abnormal stress tests or other tests showing there is not enough blood flow to the heart. Prior research has not made clear whether chest pain in such patients is due to heart disease or something else, in part because no one has found out whether chest pain and stress test results change in the same direction over time. This study will use two measurements of chest pain and two stress tests, one year apart, to find out if chest pain and abnormal stress tests are both caused by the same problem: not enough blood flow to the heart.The association between angina, ischemia and atherosclerosis severity at baseline will be examined, as will medication effects.