This is from the Advanced FCE forum heading "Blood pressure response to exercise".  You might give it a further look.  Here are some key points;

I would estimate that about 30-40 percent of my population over 40 is on some level of Beta Blocker. Although I agree that rises in heart rate for beta blocker medicated client's should not increase in proportion to the normal population (can't use norms), there is no scientific reason that a rise in heart rate for one activity that involves repetitive use of large muscle groups (stair climbing, ladder climbing, advanced treadmill walking during cardio testing), should not be expected to rise similarly for another-with a relative eqivalence in exertion.

For example, if my mild to moderately obese, 1 pack a day smoking beta blocker taking over 40 patient is found to be safe to perform an FCE, I almost always have them perform a ladder climb (if safe), as a measure of how their heart rate will respond to exertion. I document this number under ladder climb and the pace they demonstrated (HR; 122, slowed, moderate, quick), and ask them how they feel ("fine, woosy, light headed, nauseous", etc.). When it then comes time for the lifting evaluation, I now have some frame of reference as to how their HR responded when they;

a. Exerted themselves
b. Claimed fatigue
c. Were SOB
d. Threw up (just kidding)

In my opinion, there is no valid reason to dismiss the heart rate component of an FCE just because the HR is suppressed via Beta Blocker medication-provided the client demonstrates exertion during some portion of the test. I use the comparison of HR, as discussed, to both support full effort and to dismiss full effort. There are, of course, exceptions to this statement. In addition, never objectively state someones cardio test placed them in a certain category of work without the "However, these results should no be considered valid, as the client's heart rate was most likely skewed by beta blocker medication" statement.