This finding sheds new light on the commonly held theory that heart failure is an end-stage disease, with the only option for patients being a heart transplant, say the study researchers.
The study was among the first to look at beta-adrenergic receptor density and inotropic responsiveness to beta-adrenergic stimulation – the mechanisms that control the heart’s ability to contract in times of stress. In individuals with heart failure, both functions are blunted.
Researchers found that with the aid of an LVAD, these hallmarks of heart failure are reversible.
An LVAD is a mechanical pump-type device that is surgically implanted to augment the heart’s pumping ability. It can “buy time” for an individual waiting for a heart transplant and is often referred to as a “bridge to transplant.”
Researchers obtained non-failing human hearts from 15 organ donors whose hearts were unsuitable for transplantation but who had no history of cardiac disease. They obtained failing human hearts from 23 transplant patients who had not been supported with an LVAD and 19 patients who had been supported with an LVAD. The researchers used two methods in the study. They dissected muscle tissue from the hearts to compare cardiac muscle contractility at baseline and after stimulation by the drug isoproterenol. They also measured the density of beta-adrenergic receptors in non-failing human hearts and failing human hearts with or without LVAD. Results showed a significant increase in the response to beta-adrenergic stimulation after LVAD and an increased density of beta-adrenergic receptors, which indicate improved muscle performance.
Nearly 5 million Americans are living with heart failure. There are about 550,000 new cases diagnosed each year while the number of heart donors remains unchanged, according to the researchers. They say that more studies need to be done in order to determine whether the LVAD or other medical or surgical therapies could replace the need for heart transplants.
Monique L. Ogletree-Hughes, Ph.D., post-doctoral fellow, The Cleveland Clinic Foundation, Cleveland, Ohio; 216-445-5046; ogletrm@ccf.org.
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