Increased Inflammation in South Asians After CABG Surgery

November 23, 2011

November 22, 2011 (Orlando, Florida) — South Asian individuals undergoing CABG surgery have significantly increased systemic inflammation in response to cardiopulmonary bypass, and this increased inflammatory response might explain their higher rate of mortality following cardiac surgery.

Dr. Subodh Verma

"There is something unique about the South Asian population with regard to their perioperative response to cardiopulmonary bypass that may help explain why they have poorer outcomes compared [with whites]," senior investigator Dr Subodh Verma (University of Toronto, ON) told heartwire . "It might not just be all about their risk factors, all about their burden of disease, or the size of their blood vessels, it might also be that they're primed to mount a greater inflammatory response to the heart-lung machine."

The study, presented last week at the American Heart Association (AHA) 2011 Scientific Sessions, was intended to investigate why South Asian individuals have a higher risk of mortality after CABG surgery. To heartwire , Verma noted that South Asians differ from whites, including having higher rates of cardiovascular disease, developing the disease at earlier ages, being at an increased risk of MI, and having differing risk factors.

In CABG, all patients typically develop a systemic inflammatory response to cardiopulmonary bypass. The inflammatory response syndrome has been linked with an increased need for blood transfusions, kidney failure, lung failure, and heart failure, among other adverse outcomes. In their study, Verma, along with lead investigator Dr Sébastien Trop (University of Toronto), investigated whether the systemic inflammatory response differed in South Asian patients undergoing CABG when compared with white patients undergoing surgery.

In total, 37 patients scheduled for elective CABG were included in the study. Compared with whites, the researchers observed that in response cardiopulmonary bypass, the South Asian patients appeared to mount a greater inflammatory response, with patients having significantly higher levels of proinflammatory cytokines. The increase in cytokines, such as interleukin-6, was significantly correlated with the Sequential Organ Failure Assessment (SOFA) score, a validated measure of postoperative morbidity.

"For the first time, we were able to demonstrate that South Asians behave differently [from whites], even after adjusting for other important variables," said Verma. "Ethnicity by itself is a trigger for the greater inflammatory response during cardiopulmonary bypass, and that heightened response seen in South Asians might be related, in turn, to the increased morbidity seen in the postoperative period. It might be one of the reasons these patients have a higher rate of mortality."

They also found that South Asian patients had a higher surface expression of toll-like receptor-4 (TLR4) and increased levels of p38 mitogen-activated protein kinase (MAPK) and pAKT, and this means that there likely was increased TLR4 signaling in inflammatory monocytes compared with whites.

The inflammatory response during cardiopulmonary bypass causes multiorgan dysfunction, which increases the need for inotropic support postoperatively. It also results in a prolonged respiratory dysfunction, and this requires a prolonged period of intubation. Finally, it can also result in significant kidney dysfunction. To heartwire , Verma said that studies are needed to test whether South Asian patients treated with anti-inflammatory agents, such as steroids, might limit the inflammatory response during cardiopulmonary bypass and whether a treatment course could improve postoperative outcomes in this patient population.


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