 All participants will undergo myocardial flowperfusion imaging with positron emission tomography PET imaging at rest and after a standardized arithmetic mental stress test. Participants will then undergo repeat testing after 6 weeks. At 12 weeks, participants will also undergo a limited examination without myocardial perfusion imaging. The intervention group will receive biofeedback after enrollment, and the wait-list control group will receive the intervention between week 6 and week 12 study visits without imaging. 