| (Philadelphia, PA) – Researchers at the University
of Pennsylvania School of Medicine -- in the largest study
to date of female heart failure patients who underwent a specialized
stress test called oxygen uptake or VO2 -- concluded that women tend
to have lower maximum exercise VO2 levels than men, yet their survival
is significantly better than men. The results suggest that instead
of one standard cut-off level in VO2 test results for both men and
women, perhaps there should be a lower cut-off level for women. This
would allow physicians to avoid more advanced therapies in some female
heart failure patients. The study results are published in the June
6th issue of the Journal of the American College of Cardiology.
“Heart failure cardiologists utilize this special kind of
exercise test, which examines your body’s ability to utilize
oxygen during maximal exercise, to determine a course of treatment
for our patients. Up until now, there has been one absolute cut-off
level, based on VO2 stress test results, for both men and women.
It’s been the ‘gold standard’ for us to decide
the risk of proceeding with a treatment like transplant, ventricular
assist devices or other therapies,” said Mariell Jessup,
MD, Medical Director of the Heart Failure and Transplant
program and Professor of Medicine at Penn.
The VO2 is an exercise test in which a patient walks on a treadmill.
The patient is outfitted with a mouthpiece that measures the amount
of oxygen the body is using during exercise. It can determine how
well the heart muscle is delivering oxygen to the muscles of the
body in order to do work. If the heart muscle is weak, and the body
tries to exercise, the heart may not be able to keep up with the
stressful demand and deliver enough oxygen rich blood to muscles.
The test measures a patient’s ability to function (their functional
capacity to live and work).
Based on the prognosis, it helps to guide cardiologists in deciding
which advanced treatments may have to be considered for their patients.
If patients have a result below the standard cut-off level, the
cardiologist may consider a heart transplant or ventricular assist
“The physician must consider the risk of the therapy versus
the risk of keeping what the patient already has. Of all the things
we do, the maximal VO2 is the most potent predictor. We decided
to look at what happened to these patients, both men and women,
after they had the VO2 stress test done, to see how many of them
went on to receive a heart transplant and how many did not survive,”
explains Lee Goldberg, MD, MPH, an investigator
in the study and Associate Director of the Heart Failure and Transplant
program at Penn. “There have been other studies suggesting
the outcome for women with heart failure is better than men. We
took that one step further, and for the first time, went back to
investigate the outcomes of male and female patients based on what
their VO2 stress test result had been. Now, the question is –
if the VO2 is the main determinant for prognosis in heart failure,
we need to make sure we’re using the right cut-off for both
Every VO2 test done in this study was performed on the same piece
of equipment and read by the same physician resulting in few variables
and high quality data. Goldberg adds, “We tested both men
and women (nearly 600 heart failure patients total), looking at
their peak oxygen consumption results, and then watched what happened
to them. Women had a better outcome with a lower VO2 level, and
better survival at all levels of exercise capacity, signaling less
of a need for a heart transplant. More studies need to be done in
women and if we find more differences, we need to figure out if
we can capitalize on them in our therapies for heart failure.”
The investigators caution that while we now know there are gender
differences to consider in determining treatment in heart failure
patients, and that this is an important observation -- there is
much more research that remains to be done in this area.
The results of this study are published in the June 6, 2006 issue
of the “Journal of the American College of Cardiology.”
You can access the journal on-line at: http://content.onlinejacc.org/current.dtl.
The article is titled, “Effects of Gender on Peak Oxygen Consumption
and the Timing of Cardiac Transplantation.” The principal
investigator of this study and senior author is Andrew Kao, MD,
FACC. Other investigators include Sammy Elmariah, MD and Michael
This was a single site study conducted at Penn. There was no external
funding for this study.
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