Introduction
Heparin resistance (HR) is defined as need for higher than normal heparin doses to induce sufficient anticoagulation for cardiopulmonary bypass. The definitions, causes and effects of HR are still controversial in cardiac surgery practice. Our study specifically compared adult patients undergoing on-pump coronary artery by-pass graft (CABG) surgery who have received preoperative low molecular weight heparin (LMWH) with a control group who had not received any anticoagulants before surgery.
Material- Methods
Data were retrospectively reviewed from adult patients who undergone isolated on-pump CABG surgery. Patients were stratified into 4 groups according on medical regimen and presence of HR. The groups receiving preoperative LMWH was showen as LMWH+, where as the groups who does not receive preoperative LMWH was shown as LMWH -. The groups presense intraoperative HR was showen as HR+ and the groups without intraoperative HR was showen as HR-.
Material- Methods
Data were retrospectively reviewed from adult patients who undergone isolated on-pump CABG surgery. Patients were stratified into 4 groups according on medical regimen and presence of HR. The groups receiving preoperative LMWH was showen as LMWH+, where as the groups who does not receive preoperative LMWH was shown as LMWH -. The groups presense intraoperative HR was showen as HR+ and the groups without intraoperative HR was showen as HR-.
Results
Group 1 (n=55) (LMWH-/HR-), Group 2 (n=5) (LMWH-/HR+), Group 3 (n=55) (LMWH+/HR-), Group 4 (n=24) (LMWH+/HR+). All patients in Group 3 and 4 had been treated with subcutaneous injections of enoxaparin 0,01cc/kg body weight twice daily for at least 3 days prior to surgery, and the last dose was given 12 hours before surgery. Compared to the patients who had not received any anticoagulants preoperatively, patients who were treated with preoperative LMWH developed significantly higher ratio of intraoperative HR and compared to other groups, mortality rate was significantly higher in Group 4(LMWH+/ HR+).
Discussion
Our study is a rare research which specificaly compared adult patients undergoing on-pump CABG surgery who have received preoperative LMWH with a control group who had not received any anticoagulants before surgery.
In conclusion, preoperative treatment of patients undergoing on-pump CABG surgery with LMWH preoperatively may cause HR. Corrective and preventive arrangements with close follow-up should be performed in this group of patients. However, further prospective clinical researches in larger patient populations are necessary to encourage our results.
