Genetic differences may underlie the tendency of some individuals to suffer kidney complications after cardiac surgery. Testing for a gene variant might identify those most at risk, according to new research.

Summary

Some patients experience shock and kidney injury after heart surgery. The only treatment is with norepinephrine. A new study shows that patients with a gene variant in an enzyme that breaks down this drug are more at risk of post-surgery complications. This test could be used to identify those at risk before surgery so interventions can be prepared.

Introduction

Heart surgery may be life-saving but it also puts patients at risk of shock and injury to the kidneys. There is no known way of preventing this but when it happens the patient is usually treated with the drug norepinephrine which normalizes the blood pressure. But some people do not respond well to norepinephrine. The reason lies in differences in the molecular pathway that breaks down the drug and involve an enzyme called catechol-O-methyltransferase (COMT).

What was done

Researchers in Austria and Germany used a genetic test that detects variants in the COMT gene on 260 patients undergoing heart bypass surgery. They looked for a variant, called LL, that caused lower activity of COMT, making patients less responsive to norepinephrine.

What was found

The patients with the LL variant were more likely to develop shock and kidney failure after their operation, requiring a longer hospital stay.

What this study means

If the study findings are confirmed in a larger study, it may be possible to use a COMT gene test before heart surgery to identify those patients most at risk of shock and kidney failure. Their post-surgery care could then be planned carefully.

Source

Dragun D, Haase-Fielitz A et al Decreased catecholamine degradation associates with shock and kidney injury after cardiac surgery Journal of the American Society of Nephrology online April 30 2009 doi 10.1681/ASN.2008080915