Penn researchers question change in 'gold standard' for assessing heart failure treatment
Intriguing results, stemming from the largest study ever of female heart failure patients who underwent a specialized stress test, could raise larger questions about gender differences and treatment options(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 device.
"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 genders." 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: www.content.onlinejacc.org/current. 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 Allen, EMT-P.
This was a single site study conducted at Penn. There was no external funding for this study.
To schedule an interview with Dr. Mariell Jessup or Dr. Lee Goldberg, please contact Susanne Hartman at 215-349-5964 or [email protected].
For more information on the Penn Heart Failure and Transplant Program, go on-line to:
Mariell Jessup, MD -- on-line bio: www.pennhealth.com/Wagform/MainPage.aspx?config=provider&P=PP&ID=1245.
Lee Goldberg, MD, MPH -- on-line bio: www.pennhealth.com/Wagform/MainPage.aspx?config=provider&P=PP&ID=1131.
Heart Failure is a disorder in which the heart loses its ability to pump blood efficiently. It is almost always a chronic, long-term condition. Nearly 5 million Americans are living with heart failure. For more information, visit: www.pennhealth.com/ency/article/000158. PENN Medicine is a $2.9 billion enterprise dedicated to the related missions of medical education, biomedical research, and high-quality patient care. PENN Medicine consists of the University of Pennsylvania School of Medicine (founded in 1765 as the nation's first medical school) and the University of Pennsylvania Health System.
Penn's School of Medicine is ranked #2 in the nation for receipt of NIH research funds; and ranked #3 in the nation in U.S. News & World Report's most recent ranking of top research-oriented medical schools. Supporting 1,400 fulltime faculty and 700 students, the School of Medicine is recognized worldwide for its superior education and training of the next generation of physician-scientists and leaders of academic medicine.
The University of Pennsylvania Health System includes three hospitals [Hospital of the University of Pennsylvania, which is consistently ranked one of the nation's few "Honor Roll" hospitals by U.S. News & World Report; Pennsylvania Hospital, the nation's first hospital; and Penn Presbyterian Medical Center]; a faculty practice plan; a primary-care provider network; two multispecialty satellite facilities; and home care and hospice.
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