Exercise Testing

Do any of you use the FRIEND predicted equations for CPET in clinical populations? How about with heart failure or heart transplant qualification?

If you do use the FRIEND equations have you used them since your lab has been in operation or have you transitioned from other reference equations?

If you were to start a new CPET lab would you use FRIEND or Wasserman-Hansen equations?

The thresholds for normality, risk stratification, and transplant qualification will vary according to which standards are used (see Brawner et al 2020 below). In starting a new CPET lab that will be serving a wide range of clinical populations, including heart transplant candidates, I am leaning to the Wasserman-Hansen equations. It is widely used, so the reports will be more portable, and the percent predicted will be more appropriate for transplant qualification.

What do you think? Any comments would be appreciated. Thanks!

-Brian

"...any adoption of new normative references should only occur after thorough consideration of how they might affect clinical decisions. For instance, we previously showed that in patients with heart failure and reduced ejection fraction, the classification of these patients into risk categories (eg, high risk associated with ppVO2max <50%) can vary greatly depending upon the equation used to predict normal VO2max. Considering that the vast majority of studies of peak VO2 and survival in patients with heart failure have used the Wasserman-Hansen equations, the ppVO2max associated with a target absolute survival (eg, 60% survival at 2 years) must be determined before adopting a new reference. Interestingly, current heart failure guidelines statements do not address which reference equation is preferred."

Brawner CA, Ehrman JK, Keteyian SJ. Are International Standards for Exercise Capacity Ready for Prime Time? Mayo Clin Proc. 2020 Feb;95(2):218-220.

Hi Brian- At Henry Ford we continue to use the Wasserman/Hansen equations for risk stratification in our adult patients with heart failure. Over the past few years I've incorporated the FRIEND dataset in patients who are obese and referred for dyspnea evaluation. There absolute VO2 might be within normal limits per the Wasserman/Hansen equations, but their VO2/kg is low per the FRIEND dataset. It is not a good practice to mix and match datasets, but FRIEND has not reported normal values for absolute VO2 and the Wasserman/Hansen equations only report absolute VO2. Best wishes.

Hi Clinton, I'm having trouble finding the correct wasserman equation. Can you please provide the equation in this thread?

Kirill- There does not seem to be a way to post an attachment on this forum. Maybe that is something the webmaster, which is me, can turn on. IDK. In the meantime, I sent you a private message asking you to send me an email and I will send the supplement to the paper we published in MSSE. This has the Wasserman/Hansen equations and the others that we used in that paper.

At Northwestern Medicine (Chicago and surrounding areas), we also use the Wasserman-Hansen equations for CPET norms for all patients whether being tested for HF, unexplained dyspnea, etc. We include a statement on our report referencing that this is the norm set we use.

I am interested in the emerging data for norm sets but, at this point, we continue with Wasserman-Hansen. I agree with your thought about the results being more portable and widely used. Also, for us, it would be difficult to have consistency among patients with comorbidities if utilizing different norm sets in the same lab/health system.