New oral anticoagulant and antiplatelet agents for neurosurgeons

Abstract

Until recently, warfarin, clopidogrel and aspirin have provided the mainstay for prevention of thrombotic disease in cardiac patients. However, new classes of drugs have recently emerged that promise better clinical outcomes and lower risks. Use of such agents has increased, but increased risk and severity of intra-cranial haemorrhage (ICH) still remain. These cases of intra-cranial bleeds present as emergencies to neurosurgical units. It is of paramount importance that neurosurgical practitioners are aware of those new drugs, useful monitoring tests and available emergency reversal options in case the patient needs emergency intervention. In this review we survey newly available agents in the U.K. at the time of publication. We look at the data provided by the manufacturers, related publications and international guidelines for their use and reversal. New anticoagulants offer a lower incidence of ICH compared with warfarin. Advanced and accurate monitoring tests are emerging, as are prospective data on reversal of anticoagulation in bleeding. Some standard coagulation tests may be of use, whilst reversal agents are available and being evaluated. The trial data shows that new antiplatelet agents have similar or increased incidence and severity of intra-cranial ICH compared with clopidogrel. There is currently limited data on monitoring or reversal. We suggest they may be managed similarly to clopidogrel by using platelet reactivity assays, optimising platelet count and using platelet transfusion with adjunctive agents.

Platelet activation by crushed and uncrushed muscle: a flow cytometry analysis

“…It should be reiterated that platelet transfusions do not entirely reverse or negate the effect of antiplatelet agents . Blood was collected from patients already taking aspirin or clopidogrel and who had not undergone a diagnosed ischemic event in the previous 3 months.…”

Planning neurosurgical interventions in patients with anticoagulant therapy

“…During use of Dabigatran (direct thrombin inhibitor), the normal ranges of Thrombin Time (TT) or the dilute TT (dTT) is rider for associated anticoagulation effect 6 ; "safe-zone" for TT before surgical interventions is <30 ng/ml; in case of a higher values (> 30 ng/ml) or with heavy bleeding, the antidote must be administered 6 . Activated Partial Thromboplastin Time (APTT) help approximate time since the last dose 19 as prolongation result due to the anticoagulant effect 3 and suggest risk of bleeding if the value is twice the normal ratio 19 ; not done in lupus syndrome or clotting factors deficiency disorders due to the intrinsic prolonged effect of APTT that may mask the true effects 3 . Reversal with Idarucizumab depends on the available tests; in absent of testing facilities and with active bleeding doses have to be repeated 6 .…”

A Recent Update on Oral Anticoagulants

“…Dabigatran is an oral direct thrombin inhibitor that averts clot assembly by preventing fibrinogen to fibrin conversion. It is used amongst the individuals mass with NVAF the pertility to advance to stroke and systemic embolism [15]. The term "nonvalvular AF" is debatable and not easy to distinguish from "valvular AF."…”

“…In female who pertain to reproductive age group outright Oral anticoagulant drugs implementation ought to be approached with extreme vigilance to exclude the likelihood of pregnancy and contraceptive councelling guidance [13][14][15][16][17].…”