How can unstable angina be detected and/or diagnosed, particularly if the patient is not experiencing the event at the time of appointment or has not experienced it in the past month or so?

Stress testing: is almost the gold standard. Discuss with your cardiologist about the best exercise stress test in your particular situation. CPET? ECHO? thallium? or something else? Good luck

Clinical diagnosis: Unstable angina is defined as new or worsening chest pain at rest or with exertion/emotional stress. There is no test to detect unstable angina. If a blockage in the heart is more than 50% then a stress test may detect it. But if less it will not. Unstable angina can occur with any size blockage. 10% or 99% and all in between. majority of heart attacks occur with a blockage less than 50%