MILWAUKEE, Nov. 1 /PRNewswire/ -- The presence of heparin antibodies pose an independent risk for potential serious complications following cardiac surgery, according to data from the first large-scale study presented today at the annual meeting of the American College of Chest Physicians in Montreal, Quebec, Canada. Importantly, patients who did not develop the life-threatening drug reaction called Heparin Induced Thrombocytopenia (HIT) are also at a higher risk of postoperative complications.
The Aurora St. Luke’s Medical Center study demonstrated that the patients who test positive for heparin/platelet factor 4 (HPF4) antibodies are at higher risk for a number of postoperative complications including renal failure requiring dialysis, prolonged mechanical ventilation, gastrointestinal complications and acute limb ischemia.
“The clinical risk associated with HPF4 antibodies in patients who don’t have HIT syndrome is poorly understood in clinical practice,” stated David Kress, MD, leading study investigator and senior cardiothoracic surgeon at Aurora St. Luke’s Medical Center in Milwaukee, Wisconsin. “This study suggests that just having HPF4 antibodies, even without HIT or thrombocytopenia, confer a risk of adverse outcomes.”
This study is the first to control for comprehensive preoperative risk factors and uses the Society of Thoracic Surgeons (STS) National Adult Cardiac Surgery Database to evaluate postoperative outcomes. Its findings confirm prior studies that show 12.7 to 22 percent of patients who test positive for HPF4 antibodies prior to cardiac surgery, independent of HIT, are at an increased risk for complications.(1,2)
In this observational retrospective analysis, researchers followed patients undergoing coronary bypass grafting (CABG) and/or valve surgery for 2.5 years. They screened 1209 cardiac surgery patients in an unselected manner and studied the incidence of HPF4 antibodies through a blood test administered before surgery.
Of the total 1114 patients tested, 60 (5.4%) had positive HPF4 antibodies preoperatively. Adverse outcomes in the study and control groups were reported as follows:
* Higher incidence of acute limb ischemia (5.0 percent vs. 0.9 percent, p=.03) * Higher incidence of renal dialysis (11.7 percent versus 4.3 percent, p=.02) * Higher incidence of gastrointestinal complications (15.0 percent versus 5.7 percent, p=.01) * Higher incidence of prolonged ventilation greater than 96 hours (21.7 percent versus 8.8 percent, p=.01) * Longer median intensive care unit LOS (56 vs. 42 hours, p <0.05) * Two days longer median postoperative length of stay LOS (7 vs. 9 days, p <0.01)
HPF4 antibodies typically indicate that a patient has had past exposure to heparin and is at greater risk for developing a life-threatening drug reaction HIT.(3) HIT is an immune-mediated complication of heparin administration that contraindicates further heparin exposure. HIT syndrome occurs in about 3% of the patients undergoing cardiac surgery and overt thrombosis occurs in 50% of HIT patients. This condition, which involves a decrease in circulating platelets (thrombocytopenia) and an increased tendency to form blood clots, can have devastating clinical consequences such as limb ischemia requiring amputation (10-20%), myocardial infarction, stroke, pulmonary embolism and even death (20-30%).(3,4,5)
According to the National Center for Health Statistics, approximately 515,000 CABG procedures were performed on 306,000 patients and 93,000 valve procedures were conducted in the United States in 2002. The ACC/AHA 2004 Guideline Update also reports the risk of death with CABG surgeries has been the focus of numerous studies in the last two decades with patients 70 years and older experiencing a longer hospitalization and increased likelihood of morbidity after CABG. If up to 22% of these patients test positive for HPF4 antibodies prior to cardiac surgery, approximately 50,000 to over 87,000 patients are at increased risk for life-threatening conditions on an annual basis.
Previous studies have suggested risks associated with HPF4 antibodies, and adverse outcomes with antibody positivity have been observed across the spectrum of cardiac and surgical patients.(4) These findings suggest that optimal preoperative care for cardiac surgery patients should include screening for HPF4 antibody status. Diagnostic and therapeutic methods to identify and minimize the development of HPF4 antibodies during cardiac surgery may be important for reducing risk in the overall cardiac surgery patient population.
About Aurora St. Luke’s Medical Center
Aurora St. Luke’s Medical Center is a part of Aurora Health Care, a not-for-profit Wisconsin health care provider and a national leader in efforts to improve the quality of health care. Aurora offers care at sites in more than 80 communities throughout eastern Wisconsin. The STS National Adult Cardiac Surgery Database was used to obtain comprehensive and strictly defined data to evaluate preoperative risk factors and postoperative outcomes.
(1) Visentin GP et al. Patients Treated with Unfractionated Heparin during Open Heart Surgery are at High Risk to Form Antibodies Reactive with Heparin Platelet Factor 4 Complexes. J Clin Lab Med. 1996;128:376-383. (2) Slaughter TF, Bennett-Guerrero E. et al., Anti-heparin/PF4 Antibodies Detected Prior to Cardiac Surgery Identify Patients at High Risk for Adverse Perioperative Outcomes. Anesth Analg. 2002;93;SCA28. (3) Warkentin, TE, Greinacher A. Heparin-induced thrombocytopenia and cardiac surgery. Ann Thorac Surg. 2003;76;2121-2131. (4) Warkentin, TE, et al. Heparin-induced Thrombocytopenia in Patients Treated with Low Molecular Weight Heparin or Unfractionated Heparin. NEJM. 1995;332:1330-1335. (5) Rice L. Heparin-induced thrombocytopenia: Myths and Misconceptions (that will cause trouble for you and your patient). Arch Intern Med. 2004;164:1961-1964.
Aurora St. Luke’s Medical Center
CONTACT: Steve Pinzer, Aurora Health Care, +1-414-649-6419
