(Ivanhoe Newswire) – Most people come through heart surgery just fine, but some end up going into shock or experiencing kidney complications.

Now researchers from Germany and Australia help explain why. Their study links these complications to a variation in a gene involved in the metabolism of norepinephrine, the key drug used to treat shock following heart surgery.

Specifically, people with the LL variant of the COMT gene are less responsive to the effects of the drug. These individuals are also more likely to experience shock and kidney failure following heart surgery, and to require longer hospital stays as a result.

The investigators speculate the gene variant may be more pronounced in women because protective estrogen metabolities are often inactivated by norepinephrine, but they emphasize more study is needed to confirm this theory. However, they do believe the current findings on the COMT gene variation could help doctors determine post-surgery care for heart patients, if they are validated by larger studies.

The study was conducted among 260 people who underwent heart bypass surgery.

SOURCE: Journal of the American Society Nephrology, published online April 30, 2009