PURPOSE: Antithrombin therapy with heparin is the evidence-based standard treatment in patients with NSTE ACS. UFH is to be preferred in high-risk NSTE-ACS patients with planned invasive strategy. The most vulnerable part of its application is correct dosing. The aim of this analysis was to define the risk factors which are associated with the problematic dose titration of UFH in high risk NSTE ACS patients.
METHODS: We analysed a group of 267 patients with high risk NSTE ACS managed with an early (≤;48h) invasive strategy and treated with the recommended dose of UFH (a bolus of 60–80 U/kg and an initial infusion of 12–15 U/kg per hour). The subsequent dose was adjusted after measurement of aPTT, using the nomogram. The goal for activated partial thromboplastin time was 45–70 seconds.
RESULTS: 29% of patients had a therapeutic initial aPTT value (6h after starting therapy). Half of them were overcoagulated, and 22% of patients were undertreated. By continuing therapy, the proportion of optimally treated patients increased. 40% of patients reached the therapeutic dose after 12 hours of treatment, and 58% after one day. Undertreatment is a problem in ≤;65-year old men. Women and older patients have a higher risk of overdose(fig). The patients with a therapeutic dose of UFH had the lowest occurrence of combined clinical end-point death and/or re-catheterization(5%). The highest occurrence of these events were in undertreated patients(7,2%). Overcoagulated patients had the highest rate of hemorrhage(10%). Renal function per se did not influence the anticoagulation activity of UFH. We discovered a correlation between renal function and loss of haemoglobin in patients treated with a full dose of UFH (r=0,212;p=0,019; R2–0,448)(fig).
CONCLUSION: The recommended weight adjusted first dose of UFH led to an optimal antithrombin effect in less then one third of high risk patients.
CLINICAL IMPLICATIONS: An expert consensus on more precise dose guidelines for UFH is needed. The dose of UFH can be not only weight, but also age and sex adjusted.
DISCLOSURE: Zuzana Motovska, No Financial Disclosure Information; No Product/Research Disclosure Information