RELATIONSHIP BETWEEN POSTOPERATIVE ANEMIA AND CARDIAC MORBIDITY IN HIGH-RISK VASCULAR PATIENTS IN THE INTENSIVE-CARE UNIT

Objective: To determine if postoperative anemia is associated with pos toperative myocardial ischemia and morbid cardiac events Design: Case control study. Setting: Postanesthesia care unit and surgical intensiv e care unit. Patients: A total of 27 high-risk patients undergoing inf ra-inguinal arterial bypass procedures. Interventions: None. Measureme nts and Main Results: After informed consent, patients were continuous ly monitored by ambulatory electrocardiographic recorders from the eve ning before surgery up to 80 hrs during the postoperative period. Myoc ardial ischemia was defined as greater-than-or-equal-to 1 mm of horizo ntal or downsloping ST depression or greater-than-or-equal-to 2 mm ST segment elevation persisting for at least 60 secs on the ambulatory el ectrocardiogram. Morbid cardiac events were defined as: cardiac death, myocardial infarction, unstable angina, and ischemic pulmonary edema. Using a receiver operating characteristic curve, a hematocrit of 28% was determined to be the best threshold hematocrit value below which m orbid cardiac events were most likely to occur. Statistical significan ce between hematocrit and cardiac outcome was determined by Fisher's e xact test where appropriate. Thirteen of 27 patients had a hematocrit <28%. Of these 13 patients, ten demonstrated postoperative myocardial ischemia and six sustained a morbid cardiac event. Of 14 patients with a hematocrit greater-than-or-equal-to 28%, two displayed myocardial i schemia and none sustained a morbid cardiac event. A hematocrit of <28 % was significantly associated with myocardial ischemia (p = .001) and morbid cardiac events (p =.0058). No significant differences in basel ine heart rate and heart rate at the onset of myocardial ischemia were noted between the anemic and nonanemic patients. Conclusions: This st udy suggests that postoperative anemia may play a role in postoperativ e myocardial ischemia and cardiac morbidity.