May 1, 2009 - Research

Genetic Variation May Influence Heart Surgery Recovery

A common genetic variation may influence how well a person recovers from heart surgery, a study published online yesterday in the Journal of the American Society of Nephrology suggests.

Coronary artery bypass surgery, which involves using blood vessels from elsewhere in the body to reroute blood around clogged arteries feeding the heart, increases the risk of low blood pressure and shock.   Norepinephrine can be used to bring blood pressure back up to acceptable levels, but a variation in the gene for an enzyme critical to the metabolism of this drug, COMT, may make some people less responsive.

Researchers studied 260 people who had had bypass surgery and found that those who carried an A at both copies of went into shock more often compared to those with other genotypes (69% vs. 57% in AG people and 46.6% in GG people). The A version of produces a less efficient version of the COMT enzyme.

Prolonged shock, lasting more than 48 hours, was also more frequent in people with two As (25% vs. 13% for AG and 6.8% for GG). Because the body responds to shock by restricting blood flow to the kidneys, people with two As at also had greater frequency of acute kidney injury.

The median hospital stay after bypass surgery was longer for people with two As at : nine days vs. eight days for AG and seven days for GG.

More research on the effects of the COMT variation investigated in this study and variations in other genes that could also affect recovery after bypass surgery will be needed.   But if confirmed, the researchers suggest that their findings could help tailor drug regimens and lead to better outcomes.

“If confirmed in larger trials, preoperative COMT genotyping together with known clinical risk factors could aid in preoperative risk stratification to anticipate occurrence of circulatory and renal dysfunction, and prolonged recovery.   Patients thus identified may benefit from an individualized treatment…” the authors conclude.

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