Direct Oral Anticoagulant Use in Atypical Thrombosis-Related Conditions

Genetic and Non-Genetic Factors Impact on INR Normalization in Preprocedural Warfarin Management

Background

Annually, 10% of warfarin patients will likely need to stop warfarin prior to elective surgery to achieve a baseline international normalization ratio (INR) level (INR ≤ 1.2) at the time of the procedure. This study explores the influence of genetic and non-genetic factors on INR normalization in the Arab (major part of Near Eastern) population in preprocedural warfarin management.

Methods

An observational prospective cohort study was designed to recruit Arab patients taking warfarin and scheduled for an elective procedure. Two INR readings were recorded. DNA extraction and genotyping of variants in CYP2C9*2, CYP2C9*3, CYP4F2*3, VKORC1*2, and FII (rs5896) and FVII (rs3093229) genes using real-time polymerase chain reaction were performed.

Results

Data from 116 patients were included in the analysis. CYP2C9 and VKORC1 genetic variants carriers required lower maintenance dose compared to non-carriers. The analysis showed that ciprofloxacin, antiplatelet medications, and INR index (INR at visit 1) are the only factors associated with the INR decline rate. Also, the proportion of CYP2C9*3 carriers with normal INR (≤1.2) on the day of surgery was significantly lower than those with wild-type genotype (28% vs 60%, p=0.013). In addition, heparin bridging, INR target, and Sudanese nationality are significant predictors of INR normalization (≤1.2) on the day of the procedure.

Conclusion

Despite the confirmed effect of genetic factors on warfarin maintenance dose, the study was not able to find a significant effect of any genetic factor on the rate of INR normalization possibly due to the small sample size. Index INR and interacting medications showed to be significant predictors of INR decline rate.

Direct Oral Anticoagulants in Select Patients With Hypercoagulable Disorders

OBJECTIVE

To summarize the literature assessing the safety and efficacy of direct oral anticoagulants (DOACs) for the acute treatment and secondary prevention of venous thromboembolism (VTE) in select patients with hypercoagulable disorders.

DATA SOURCES

An electronic PubMed literature search was conducted from January 2010 to July 2020 using the following keywords: DOAC, rivaroxaban, apixaban, dabigatran, edoxaban, thrombophilia, cancer, antiphospholipid syndrome, protein C deficiency, protein S deficiency, antithrombin deficiency, factor V Leiden, prothrombin G20210A gene mutation, congenital thrombophilia, hypercoagulable, hereditary thrombophilia, acquired thrombophilia.

STUDY SELECTION AND DATA EXTRACTION

Articles were included if they reported clinical outcomes associated with cancer-associated VTE, antiphospholipid syndrome (APS), and other hereditary thrombophilias.

DATA SYNTHESIS

The safety and efficacy of using a DOAC is highly dependent on the type of hypercoagulable disease state. Current trials support the use of edoxaban, rivaroxaban, and apixaban for the treatment of cancer-associated thrombosis (CAT), with apixaban being preferred because of lower bleeding rates compared with standard of care. The use of DOACs, especially rivaroxaban, have been associated with worse outcomes in patients with APS, whereas data on DOAC use in hereditary thrombophilia remains scarce and limited to low-risk patients.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review evaluates the literature assessing the safety and efficacy of DOACs in patients with various hypercoagulable disorders.

CONCLUSIONS

The current body of evidence supports the use of select DOACs for the treatment of CAT. In contrast, DOAC use in patients with APS and hereditary thrombophilia should be avoided at this time.

Approaches to Direct Oral Anticoagulant Selection in Practice

Direct oral anticoagulants (DOACs) carry many advantages over warfarin and are now considered first line or an alternative for mnay thromboembolic disorders. With the emergence of 5 DOAC agents to the market as well as the accumulating evidence gathered from head-to-head comparisons between the agents, we attempt to provide direction for clinicians when selecting the most appropriate DOAC agent. Important aspects such as efficacy, safety, cost effectiveness, approved indications, and other drug-related factors will be addressed to highlight the major similarities and diversities among the DOACs. When considering the safety profile of DOACs, evidence points toward apixaban as the safest followed by dabigatran and then rivaroxaban. On the other hand, dabigatran currently has the only approved antidote, idarucizumab. According to the approved DOAC indications, rivaroxaban may be favorable in European countries given its additional indication for secondary prevention of myocardial infarction. Following rivaroxaban, dabigatran and apixaban have the largest number of approved indications and lastly comes edoxaban and then betrixaban. For patients with renal impairment, betrixaban is the safest option, followed by apixaban and edoxaban, then rivaroxaban and lastly dabigatran. When considering DOAC dosing, rivaroxaban, edoxaban, and betrixaban are mainly dosed once daily compared to dabigatran and apixaban, which are dosed twice daily. However, rivaroxaban and betrixaban must be administered with food, which adds another level of complexity to the DOAC dosing. Lastly, taking into consideration drug interactions, dabigatran, edoxaban, and betrixaban have the least amount of interactions compared to apixaban and rivaroxaban. Each DOAC has its own set of features that makes it better suited than others based on the exact clinical situation. Therefore, no conclusion can be drawn to the most superior DOAC based on the aspects discussed in this review.