Exercise Testing

Hello all. Wanted to generally poll those of you working in exercise testing area. I am working on a presentation to our team. Over past few years, have had an increase in how differently our providers/physicians handle tests where patients do not meet the rather arbitrary 85% of predicted max (220-age) at a level that must be attained before they call testing "diagnostic"

As those of us in this profession know, there is nothing actually magical about reaching 85% of predicted max, in fact if a patient does not have a good HR response to exercise that might be the answer you were looking for, especially in those with dyspnea on exertion and exercise intolerance.

Wanted to know from those of you who conduct testing:
1. do you use it as a cut-point where you call a test diagnostic.
2. if is used as solid black and white criteria to follow up with pharmacological testing
3. as a solid cut point to inject radio-isotope for nuclear imaging stress tests?


Thanks for any feedback you provide.

Mark: We use 85% or RPP<25000 as criteria to include a statement that the test results may have reduced sensitivity. If a patient does not reach 85% during an exercise nuclear study they are switched to regadenoson. 

1. Every cardiac diagnostic clinic I've worked in has used 85% as the "adequate/inadequate" determination.

2. Typically our physicians would recommend following up with pharmacologic testing if the patient reached aprox. <70-80% MPHR during exercise (w/ no ST changes). We were fortunate to have a "standing order/protocol" with our clinic physicians that allowed us to go ahead and switch to pharmacologic testing provided the patient was unable to reach 85% or develop symptoms on the treadmill.

3. I used to perform a variety of stress tests on patients in a private cardiology clinic. During nuclear stress testing, we would wait to inject the Cariolite (isotope) when the patient stated they could only exercise for 1 more minute - sometimes this was very close to 85% MPHR and sometimes this was well beyond 85% MPHR. It didn't make much sense for us to inject a patient with Cardiolite at 85% when they could ultimately reach >= 100% MPHR and possibly develop ST changes after the 85% HR. If the patient could not reach 85%, but developed ST changes, then we would go ahead and inject the Cardiolite.

Hope this helps. Sorry for the late response.

Hi Oliva. Never too late. Essentially my point is that anyone who is not able to perform to their peak has the potential to cause reduced sensitivity, regardless of if they hit 85%. In my opinion, their is an overuse of 85% being some kind of gold standard to reach during exercise. Each and every person should be considered individually, in fact, not being able to reach 85% may very well have answered the question at hand, they might just be chronotropically incompetent. So if this person did not have symptoms or ECG changes, but appears to have given their full effort, why not refer to cardiology and if later down the line they want more stress testing, let them develop that plan of care.

Mark, well said. As you know, we do mostly cardiopulmonary stress testing at our facility. We use a combination of % predicted HR, RER, and % predicted VO2 when writing our reports. If any one of those values is too far below what we would normally expect to see at near maximal exercise, a comment goes into the report stating that the low value **may** indicate a submaximal effort/performance on the part of the patient and possibly affect the validity. We try to provide as much data to the physicians as we can and guide their interpretation of the test when needed.

Olivia, good to hear you're doing what you're doing with your nuclear imaging GXTs. It sounds like you're right on point with best practice for obtaining the best quality data for the patient and physicians.

Yes I so agree !! It does not make since to inject at 85% if they can go beyond that very easily.

Unfortunately most tests are run by RNs just following a protocol and do not individualize target rates.

I happen to be both a CEP and a RN. My vo2 max is 43 and my RHR 60 bpm, and I am 59 yo. They injected me at 85% so I really consider my test useless. Test was normal.

Although I also know the correlation between ischemic heart disease and an excellent level of fitness is very low...but in my clinic, I have seen ischemic changes (ST straightening and downsloping) at a very high level of exercise.

Thank you for posting.

Another thing I think is that 85% point of injection was studied in the past and found that only 60% of significant CAD was captured, leaving 40% not. Do not totally quote me on that, but I think it is correct.