This observational study will enroll up to 773 patients who participated in either AI-700-32 or AI-700-33 and who were evaluated with AI-700 contrast ECHO at rest and at pharmacologic-induced stress. Approximately 28 international study centers will participate. At the time of AI-700 contrast ECHO (defined as the index date), the patients were to have had a recent history of chest pain and were to meet all eligibility criteria. Chest pain (angina) was defined as either: