Duke University Medical Center researchers have discovered that patients who have two specific gene variants are more than three times as likely to suffer a stroke after heart surgery.
Furthermore, since the two implicated genes are involved in the body's immune response to insult or injury, the researchers said that their findings strongly suggest that inflammation plays an important role in post-operative stroke.
The researchers said that if the findings are confirmed by more extensive studies, they could become part of a battery of genetic tests to better identify the risk to patients of stroke after surgery.
"Despite all our advances in improving outcomes after cardiac surgery over the decades, stroke remains a significant and debilitating complication," said Duke cardiothoracic anesthesiologist Hilary Grocott, M.D., whose study results were published early on-line in the journal Stroke. The study was supported by the National Institutes of Health and the American Heart Association.
"As the population of patients getting cardiac surgery continues to age, it is important for us to better understand all the factors that impact mortality and the quality of life for these patients," he continued. "Discovering that these two genes are linked to stroke after heart surgery is an important first step that should now be validated by larger studies."
While it is still too early to change clinical practice based on the findings of the Duke team's findings, Grocott said that in the not-too-distant future physicians will be better able to define a specific patient's risk for adverse outcomes after heart surgery based on a spectrum of genetic and clinical information.
"When discussing the risks and benefits of surgery, it is important to patients to know whether they are at a higher or lower risk," he said.
For their study, the researchers selected 26 genes implicated in past non-surgical studies as possibly playing a role in the incidence of stroke. The genes identified regulate three general processes – coagulation, inflammation and lipid metabolism.
After identifying the candidate genes, the researchers then consulted a databank of 1,635 patients enrolled in an ongoing Duke study on the role of genetics in cardiac surgery outcomes. Of those patients, 28 (1.7 percent) suffered a stroke after surgery. Nationally, the reported incidence of stroke after heart surgery is approximately two percent but can vary widely, Grocott said.
The researchers then analyzed blood samples to determine whether specific variants, known as polymorphisms, of the 26 candidate genes, either alone or in various combinations were associated with stroke.