I have a family member who has had a 40% blockage in their coronary artery for the past 5 years (at least this is when the blockage was detected). Since then, this person has been seen by his cardiologist 3 times in which each visit yielded a stressed test followed by a catheter. The first 2 times these tests were performed, my family member failed his stress test while the catheter revealed a 40% blockage. This 3rd and last series of tests revealed the same, however, the cardiologist mentioned that the latest stress test looked a bit worse than the previous 2 tests. Even though the cardiologist mentioned this, there was no further course of action leaving my relative concerned about his worsening stress test results.
Therefore, my question would be: can a stress test reveal something that a catheter cannot? From what I understand, a stress test will show blood flow to the muscles of the heart, while a catheter focuses more on any blockage. I understand that there is often times a correlation here, however, I am guessing that other factors such as valve function etc that can lead to a worsening stress test while not being detectable by a catheter. Should my family member request a follow up as to why his stress test has worsened but his catheter results stayed the same?