Half-dose enoxaparin vs. full-dose enoxaparin for postoperative bridging therapy in patients after cardiac surgery: Which dose regimen should be preferred?

Abstract

Patients who require oral anticoagulation (OAC) after cardiac surgery due to an increased risk for thromboembolic events should receive bridging therapy with heparin until the INR is in a therapeutic range. For this purpose, unfractionated heparin (UFH) or low molecular weight heparin (LMWH) can be used. Recently published studies have demonstrated the safety and efficiency of therapeutic dose LMWH as bridging anticoagulant in cardiac surgery. The present study compares a full-therapeutic dose regimen with a half-therapeutic dose regimen of LMWH looking for safety and efficiency. This study represents a retrospective, single-center cohort study. In a period of 19 months all patients in whom a postoperative bridging therapy after cardiac surgery was necessary (atrial fibrillation, mechanical heart valve replacement, tricuspid valve repair, intracardiac patch implantation, excision of intracardiac tumors) were selected. In the first part of the study, patients received full-dose (FD = 1 mg/kg bodyweight twice daily) LMWH (Enoxaparin). Analogously, patients in the second part of the study were treated with half-dose (HD = 0.5 mg/kg bodyweight twice daily) LMWH. In case of renal insufficiency (GFR <30 ml/min) the dose was adjusted to one daily application. The duration of follow-up was the patients' entire stay in hospital. Main outcome parameters were bleeding, thromboembolic events, and death. The first dose of LMWH was given on the morning of the first postoperative day, considered that the bleeding risk was acceptable. OAC (Phenprocoumon) was started on the evening of the first postoperative day. Altogether 402 out of 3133 patients met the inclusion criteria (201 patients in each group). Despite a reduced renal function in the HD-group (p = 0.002) both groups were well matched. Mortality was significantly higher in the HD-group than in the FD-group (5.5% vs. 0.5%, p = 0.003) but not related to the anticoagulation regimen. We observed more bleeding events in the FD-group (11 vs. 5, p = 0.126) but vice versa more thromboembolic events in the HD-group (9 vs. 5, p = 0.277). In the HD-group postoperative dialysis was required more often (29 vs. 12, p = 0.011) and there was a higher incidence of patients who were psychic disorientated (42 vs. 26, p = 0.033). The hospital stay was longer in the FD-group (FD: 15.1 ± 9.3 days, HD 12.5 ± 8.1 days, p = 0.003). This study shows that a bridging therapy with LMWH is feasible and safe no matter which dose-regimen is used. The differences observed seem not to be related to the anticoagulation. The decision of using a full-dose or half-dose LMWH bridging regimen should be determined by the individual risk of the patient and the general bleeding risk of the procedure.