To ensure that patients' baseline health status did not influence results, the researchers assessed each patient's predicted surgical risk using a standardized risk scoring system called the Parsonnet risk score. This system is based on 19 factors known to be associated with death or other complications after heart surgery. The researchers found that regardless of the Parsonnet score, patients with heparin antibodies before surgery fared worse than patients without the antibodies.
More than 350,000 adult cardiac surgeries are performed in the United States each year. In this study, as many as13 percent of surgical patients were found to have heparin antibodies before undergoing surgery.
Slaughter says there is no simple solution to the problem. Several anti-clotting medications may provide an alternative to heparin, but they are not approved by the Food and Drug Administration for use during heart surgery. The safety of these alternative medications in the setting of complex heart surgery remains to be determined.
Another option may be for patients with the antibodies to delay surgery until the antibody levels subside. However, in some cases this might require months and, in many cases, the severity of a patient's disease may not allow for safe delay of surgery.
"Researchers are at the cutting edge of learning about heparin antibodies and how they affect surgical outcomes," said Slaughter. "We need to understand more about mechanisms underlying the adverse effects of heparin antibodies and whether alternative anti-clotting medications will prove safer before informed recommendations can be made to patients and surgeons."