The Influence Of Low-molecular-weight Heparin (LMWH)to Plasma Anti-Xa In Acute Coronary Syndromes

Objective:To observe the influence of low-molecular-weight heparin (LMWH) on plasma anti-Xa level and its change features.At the same time,we also want to observe the influence of different dosage of LMWH on anti-Xa activity and their difference.Method:There are patients with ACS as experimental groups and13patient with PSVT as control. All patients were randomized to4group:(1)the rountine dose of enoxiparin:24patients,received enoxiparin40mg q12h;(2)the rountine dose of nadroparin:16patients,received nadroparin0.4ml ql2h;(3)the routine doses of dalteparin:20patients, received dalteparin5000u ql2h;(4)the standard dosage of enoxiparin:22patients,received enoxiparin1mg/Kg.Plasma anti-Xa were measured with the specific chromogenic substrate in82patients with ACS and13controls.Plasma anti-Xa were measured immediately,and at4h,24h, and day3after initial injection.Result:(1)In the early onset of ACS patients,the density of Fg is higher than that of control (p<0.05). PT, APTT, ACT:there are no significant difference with the control group. In the early injection of LMWH, the change of Fg is not obvious, after three days,Fg significantly increased compared with before treatment (P<0.05).After24hours and3days,PT decreased compared with before(p<0.05). APTT, ACT:the difference between LMWH injection before and after have no significant(P>0.05).(2)Plasma anti-Xa level in ACS patients are significiantly higher than those in controls(anti-Xa0.021±0.09, P<0.05).(3)In the conventional dose group, anti-Xa levels reached the peak at4h, and then gradually decreased. At4h, the increase of anti-Xa level in enoxiparin is higher than these in nadroparin and dalterparin groups (P<0.05). At24h and3d, the increase of anti-Xa level in enoxiparin and nadroparin group is higher than that in dalterparin (P<0.05). However, there are no difference between enoxiparin and nadroparin (p>0.05). (4)In the group of standard dose of enoxiparin, plasima anti-Xa leveal is higher than the group of conventional dose of enoxiparin at4h and24h after initial injection (P<0.05),there is no difference between them at3d (P>0.05).Conclusion:Activity of anti-Xa increased significantly in ACS patients.LMWH can influence the Xa but can not influence the APTT. With the intervention of LMWH,anti-Xa can reach the peak at4h.But the anti-Xa is lower than the0.5u/ml under the routine doses. In the clinical application,it should be considered to adjust LMWH dosage according to body weight. If the condition allowed,it should monitor the anti-Xa activity level.