Biomarker Found for Heart Failure

Scientists have discovered an enzyme in the blood that could be a potential marker for heart failure, according to a new study reported in the July 29, 2005, online edition of the European Heart Journal.

In the study, the scientists compared tissue samples from a group of 24 patients with heart failure in need of transplants with tissue samples from 58 patients who were not sick but had various stages of left ventricular malfunction. The results showed that the sicker patients had higher levels of an enzyme called beta-adrenergic kinase (ßARK1), or GRK2.

"We can track levels of this kinase with a simple blood test,” said Walter Koch, Ph.D., professor of medicine and director of the Center for Translational Medicine at Jefferson Medical College (Philadelphia, PA, USA), who led the team of scientists.” It appears consistent with the numerous animal studies we have done. When GRK2 is elevated in the blood, patients have more severe heart failure. It's a potential biomarker for heart failure.”

Animal studies have shown that the expression of GRK2 appears to be regulated by hormones called catecholamines, which include norepinephrine and epinephrine. These are message-carrying neurotransmitters in the sympathetic nervous system. In heart failure, this system is in overdrive, and levels of these hormones are high. In congestive heart failure, the beta-adrenergic receptor system fails to work properly. One function of GRK2 is to turn off beta-adrenergic receptors.

"In heart failure, beta adrenergic receptor density is decreased, ßARK is increased, and both together cause dysfunctional beta receptor signaling,” added Dr. Koch. "A failing heart then has little capacity to respond to exercise or stress because there are fewer receptors, and remaining receptors are more or less turned off.”