A prospective and randomized comparison of the safety and effects of therapeutic levels of enoxaparin versus unfractionated heparin in chronically anticoagulated patients undergoing elective cardiac catheterization

Consecutive patients with atrial fibrillation and/or prosthetic heart valves, receiving chronic anticoagulation with phenprocoumon and scheduled to undergo cardiac catheterization, were randomized to subcutaneous enoxaparin twice daily (n = 32) or intravenous UFH (n = 36). Cardiac catheterization was performed at an international normalized ratio <1.5. Activated partial thromboplastin times and levels of anti-Factor Xa activity were measured daily. The time until effective anticoagulation (primary endpoint) was significantly shorter for enoxaparin than for UFH (1.1 +/- 0.4 days versus 3.7 +/- 2.5 days, p<0.0001). The percentage of days of effective anticoagulation was significantly higher in the enoxaparin group than in the UFH group (93.3 +/- 9.5% versus 53.7 +/- 26.6%, p <0.0001). In conclusion, enoxaparin achieves therapeutic levels of anticoagulation more rapidly and consistently than UFH in chronically anticoagulated patients with prosthetic heart valves and/or atrial fibrillation undergoing cardiac catheterization.