SNPwatch: Genetic Variation May Influence Heart Surgery Recovery

SNPwatch gives you the latest news about research linking various traits and conditions to individual genetic variations. These studies are exciting because they offer a glimpse into how genetics may affect our bodies and health; but in most cases, more work is needed before this research can provide information of value to individuals. For that reason it is important to remember that like all information we provide, the studies we describe in SNPwatch are for research and educational purposes only. SNPwatch is not intended to be a substitute for professional medical advice; you should always seek the advice of your physician or other appropriate healthcare professional with any questions you may have regarding diagnosis, cure, treatment or prevention of any disease or other medical condition.

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 rs4680 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 rs4680 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 rs4680 also had greater frequency of acute kidney injury.

The median hospital stay after bypass surgery was longer for people with two As at rs4680: nine days vs. eight days for AG and seven days for GG.

(23andMe customers can check their data for rs4680 using the Browse Raw Data feature.)

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.

  • Having two As at rs4680 in the COMT gene has been associated with a number of conditions, ranging from neuropsychiatric and hormonal disorders to cardiovascular diseases. 23andMe customers can read about how this SNP interacts with tea drinking to affect breast cancer risk in the Breast Cancer Risk Modifiers Research Report.  There is also a Research Report about another SNP in the COMT gene and its effects on pain sensitivity.