"These findings are contrary to conventional thinking that a kidney transplant may put additional strain on the hearts of patients with systolic heart failure," says the lead author of the study, Ravinder K. Wali, M.D., a nephrologist at the University of Maryland Medical Center and assistant professor of medicine at the University of Maryland School of Medicine. "We were surprised to find that, in fact, many of those people with severe heart failure had striking improvement in terms of cardiac function after a kidney transplant."
Dr. Wali adds, "Our study also found that systolic heart failure was more likely to be reversed if patients received a transplant soon after they began dialysis to treat their kidney failure."
The study followed 103 patients between June 1998 and November 2002. Prior to their transplant, all of the patients had congestive heart failure with a left ventricular ejection fraction of 40 percent or less. The ejection fraction is a measure of the ability of the heart to pump blood. In the normal ejection fraction, the heart is capable of pumping more than 55 percent of the blood volume in the ventricle. The researchers assessed the heart's pumping ability of the patients at six and 12 months and at a later follow-up visit after successful transplantation.
Overall, after a kidney transplant, the heart's pumping ability improved in more than 86 percent of the patients. For 70 percent of the patients, pumping ability returned to normal or close to normal following the transplant. Even more dramatic, the majority of the patients with the worst heart failure (about 20 percent of those studied) regained significant cardiac function following the transplant, according to Dr. Wali.
The investigators also observed major recovery in patients whose heart failure included blocked or narrowed heart arteries, a condition known as ischemic heart failure. "We showed that the ejection fraction went up even among those who had undergone coronary artery bypass surgery," says Dr. Wali.
The most important factor that directly affected recovery of the heart function was the length of time the patient was on dialysis. The study was not large enough to determine how long a person can remain on dialysis and still receive a cardiac benefit from a kidney transplant.
"Our conclusion," says Dr. Wali, "is that your best chance of survival, if you have both kidney failure and heart failure, is to receive a kidney transplant as soon as possible." He says this group of patients should be encouraged to seek a living kidney donor since the national waiting time for a deceased donor kidney transplant can average three to five years, according to the United Network for Organ Sharing.
Dr. Wali says it is not clear why prolonged dialysis reduces the benefits of kidney transplantation for the heart, but he says there are several toxins associated with end-stage renal disease that have an adverse effect on the muscles of the heart. It may be that some of those toxins are not totally eliminated during the process of dialysis and that long-term exposure to those toxins increases the risk of death from cardiac causes.
In an editorial accompanying the article in the Journal of the American College of Cardiology, the authors underscore the complexity of heart-kidney interactions and point to the need for further study. "The clinical implications of the study lend credence to the notion that renal transplantation can be performed safely in patients with advanced stages of heart failure due to left ventricular dysfunction," says the editorial.
The editorial was written by Hector O. Ventura, M.D., F.A.C.C., of the Ochsner Clinic Foundation in New Orleans and Mandeep R. Mehra, M.D., F.A.C.C., formerly of Ochsner, who is now head of cardiology at the University of Maryland Medical Center and professor of medicine and head of the Division of Cardiology at the University of Maryland School of Medicine.
In an interview, Dr. Mehra said, "This is an amazing study. It reverses the usual sequence of scientific inquiry from laboratory bench to patient bedside. Instead, astute observation at the bedside is prompting investigators to the laboratory, where they can systematically seek to understand why kidney transplantation successfully treats heart failure."