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Aspirin is not recommended for the prevention of thromboembolism in NVAF due to decreased efficacy and no difference in bleeding risk compared to anticoagulant therapy. The Garfield-AF registry reports that NVAF patients on antiplatelet monotherapy for stroke prevention tend to have higher HAS-BLED scores suggesting that clinicians may be unfamiliar with guidelines and studies revealing similar bleeding risks of anticoagulants and antiplatelet agents. The AVERROES trial showed no significant difference in bleeding with apixaban vs. aspirin. A recent meta-analysis of 4 randomized controlled trials with greater than 20,000 patients, showed no significant difference in outcomes of major bleeding with therapeutic direct oral anticoagulant (DOAC) dosing vs. aspirin. Guidelines from the United States and Europe (CHEST 2018, ESC 2016 and AHA/ACC/HRS 2019) all recommend anticoagulants over antiplatelets and the ESC recommends against antiplatelet therapy used for stroke prevention in NVAF patients.

Resources

• Verheugt, European Heart Journal. 2018; 39(5):464-473
• Dimitrios Sagris, et al., European Journal of Internal Medicine. https://doi.org/10.1016/j.ejim.2020.05.001
• Connoly, NEJM 2011; 364:806-817.
• Lipp, CHEST 2018;154(5):1121-1201.
• European Society of Cardiology 2016; 37, 2893-2962
• January, Circulation.2019;140:e125–e151.

It should first be noted that in the large pivotal trials that brought the DOACs to market, enrolled patients were assigned a dose based on renal function at study randomization without changes during the study period. Subgroup analyses of the ARISTOTLE and ROCKET-AF trials demonstrated that – in patients experiencing worsening renal function during the study period - apixaban and rivaroxaban maintained their efficacy and safety benefits as compared to warfarin. It should also be noted that studies have identified off-label DOAC dosing (including under- and over-dosing for renal function) as a common problem that significantly increases the risk of major bleeding, thromboembolic events, and all-cause mortality. As such, guidelines and experts note that patients prescribed DOACs require regular monitoring of renal function to ensure their safe and effective use – with dose adjustments made according to the renal dosing parameters for each DOAC agent. However, it may be impractical and unnecessary to frequently adjust the dose when a patient’s renal function is slightly fluctuating across parameter endpoints. DOAC dosing decisions should be based on factors such as the extent of creatinine change, the overall trend in renal function, and the clinical plan in response to the changing renal function (i.e., repeat labs, work-up, adjustments to medications which may be causative, etc). Other considerations that may sway a decision include (but are not limited to), drug-drug interactions, perceived bleeding/thrombotic risk, and patient preference. An approach that limits frequent dose changes and promotes shared decision-making between the patient and prescriber is recommended.

Resources

• JAMA Cardiol. 2016;1:451-460
• Circulation. 2016;134:37-47
• J Am Coll Cardiol. 2016;68(24);2597-604
• J Am Coll Cardiol. 2017 Jun 13;69(23):2779-2790

The 9th edition of the ACCP Antithrombotic guidelines (CHEST 2012) states the following:

For patients with stable therapeutic INRs presenting with a single subtherapeutic INR value, we suggest against routinely administering bridging with heparin (Grade 2C).

It should be noted that this is not specific to MHVs, does not speak to repeatedly subtherapeutic INR, and does not speak specifically to high-risk indications. One could extrapolate from current recommendations about bridging for intentional interruptions, but this does not add much clarity to the issue if the guidelines and available literature are taken in context. First, the annualized stroke risk associated with MHVs has been estimated at 2-4% so one can assume a daily risk of no more than 0.01% - quite low. While some societies still encourage periprocedural bridging for certain patients with MHVs, it should be clear that all available literature would suggest net HARM from bridging in all patient populations represented in studies to date. Across the board, the data demonstrates no significant reduction in the risk of thromboembolic events, with significant increase in the risk of major bleeding. Clear data on the risk and benefit of bridging in the highest risk population (including the highest risk patients with MHVs) are lacking, but the net harm from other populations seems so clear that the likelihood of any population exhibiting net benefit is low. As such, bridging for a single subtherapeutic INR should likely be avoided in most cases. For the highest risk patients and/or those with multiple subtherapeutic INRs, the above should be taken

Resources

• CHEST 2012; 141(2)(Suppl):7S–47S.
• Circulation. 2017;135:e1159–e1195.
• European Heart Journal (2017) 38, 2739–2791.
• J Am Coll Cardiol 2000; 86:1097–101.

As of this writing, there exists no prospective AF nor VTE trial data involving patients with ESRD prescribed any of the direct-acting oral anticoagulants (DOACs). Such patients were excluded from the large randomized controlled trials of DOACs vs. warfarin for these conditions. Further, none of the DOACs have FDA approval for use in this specific population. Both apixaban and rivaroxaban include language in their prescribing information about use in these populations that is based on pharmacokinetic modeling data involving a SINGLE DOSE of the respective agents administered to eight study subjects. A steady state pharmacokinetic modeling study published in 2017 found that apixaban 2.5mg twice daily given to patients on hemodialysis (HD) resulted in drug exposure comparable to that of apixaban 5mg twice daily given to pts with preserved renal function. It concluded that apixaban 5mg twice daily resulted in supratherapeutic levels and should be avoided in the HD population. However, a more recent retrospective outcomes study evaluating the use of apixaban in patients with AF and ESRD concluded that "apixaban may be associated with a lower risk of major bleeding compared with warfarin, with a standard 5mg twice a day dose also associated with reductions in thromboembolic and mortality risk."" As this likely represents the best available data, it would appear that following the AF dosing recommendations in the prescribing information represents the best approach.

As for VTE, there exists no available data to inform decisions.

Resources

• Eliquis (apixaban) prescribing Information
• Xarelto (rivaroxaban) prescribing information
• J Am Soc Nephrol 2017. 28: 2241–2248
• Circulation. 2018 Oct 9;138(15):1519-1529

The WATCHMAN procedure is indicated for the prevention of stroke in patients with atrial fibrillation (AF) and involves the implantation of an occlusive device in the left atrial appendage (LAA) of the heart.¹ More than 90% of AF-related thrombi originate in the LAA making LAA closure (LAAC) an attractive option. The WATCHMAN is associated with stroke reduction similar to warfarin, but with a long-term major bleeding reduction.^2,3,4 Left atrial appendage closure (LAAC) can also be cost-effective in the long-term.⁵ However, there are risks associated with the WATCHMAN, including the risk of procedure-related major bleeding, and risk of stroke from incomplete LAAC. Some opponents have also raised concerns about insufficient data and lack of compelling evidence supporting the WATCHMAN.⁶ Additionally, the WATCHMAN was compared ONLY to warfarin. For patients who are poor candidates for long-term warfarin therapy, the use of safer, more effective, and more convenient anticoagulants (i.e., Direct-Acting Oral Anticoagulants) should be considered before LAAC with WATCHMAN.⁷

Resources

Since DOACs exhibit a similar pharmacokinetic profile as LMWH, the use of parenteral bridging is generally not a recommended strategy for perioperative management. For high risk procedures, it is recommended that DOACs be held 3-5 half-lives to achieve maximal drug clearance.

Resources

• ASRA Guidelines
• How to manage patients who need a procedure, April 2014
• AC Forum Guidance - DOAC Management

Recent literature has shifted the landscape on how perioperative bridging should be approached. In most cases bridging with LMWH is associated with more risk of bleeding than prevention of VTE. Instances where bridging could be considered are:

1. Active cancer
2. Recent VTE (within 3 months)
3. Strong Thrombophilia (APS, protein C/S def or antithrombin deficiency)
4. Previous therapeutic failure or VTE during short term interruption
5. Patient undergoing procedure with high thrombotic risk

Resources

• A Call to Reduce the use of Bridging Anticoagulation
• American College of Cardiology Periprocedural Guidance

Recent publications have highlighted that “off-label” DOAC dose reductions correspond with higher incidence of thromboembolic events. Presently, “off-label” dose reductions should be avoided.

Resources

• Off-Label Dosing of Non-Vitamin K Antagonist Oral Anticoagulants and Adverse Outcomes
• Non-Vitamin K Anticoagulant Dose Selection: It’s Best to Read and Follow the Directions

It is best to avoid the use of DOACs in patients with APLS. Warfarin or LMWH should remain first line options until more data becomes available.

Recommendations from the International congress of Antiphospholipid Antibodies Task Force:

“The taskforce recommends that warfarin or other VKA remains the mainstay of anticoagulation in thrombotic APS. Oral direct inhibitors can be considered in APS patients with a first or recurrent VTE occurring off or on subtherapeutic anticoagulation, only when there is known VKA allergy/intolerance or poor anticoagulant control. There are no data to recommend ODI (oral direct inhibitors) in APS patients with recurrent VTE occurring on therapeutic anticoagulation or with APS-related arterial thrombosis”

Resources

• 14th International Congress on Antiphospholipid Antibodies Task Force Report on Antiphospholipid Syndrome Treatment Trends

Recent studies such as the BRIDGE trial have demonstrated that there is a net harm associated with LMWH bridging. Consideration for bridging should be reserved for patients who are at high risk for thromboembolism such as:

1. Patients with any thromboembolism during past interruptions of anticoagulation, or while on therapeutic anticoagulation
2. Patients with a cerebrovascular accident or transient ischemic attack in the past 3 months
3. Patients with recent (within 1 month) evidence of mural thrombus or left atrial appendage clot
4. Patients with a mitral mechanical valve
5. Patients with older caged ball or tilting disc mechanical valves
6. Patients with VTE in the past 3 months
7. Patients with VTE and a properly diagnosed hypercoagulable state, including antiphospholipid antibody syndrome,
8. Protein C or Protein S deficiency, or antithrombin3 deficiency.
9. CHADS2 score of 5-6 or CHADS2VASc score of 7-9

Additional guidance is available from the American College of Cardiology at:
American College of Cardiology Periprocedural Guidance

In patients undergoing major orthopedic surgeries who do not require bridging, it is still necessary to consider post-operative VTE prophylaxis, due to the high risk of thromboembolism associated with major orthopedic surgeries, until full dose anticoagulation is cleared by the orthopedic surgeon.

In very high risk patients in whom full dose bridging is deemed necessary, it is recommended risks and benefits be discussed with the proceduralist to determine the best course of action for the patient.

Resources

• A Call to Reduce the use of Bridging Anticoagulation
• Prevention of VTE in orthopedic surgery patients - Article 1
• Prevention of VTE in Orthopedic Surgery Patients - Article 2

The CHEST guidelines provide recommendations for lower extremity SVT (not upper). If the SVT is >5cm, recommendations are to utilize prophylactic dosing of fondaparinux.

Patients with superficial venous thrombosis of the lower limb of at least 5 cm in length. Suggest the use of a prophylactic dose of fondaparinux or LMWH for 45 days over no anticoagulation.

Currently, none of the DOACs have FDA approval to treat SVT, however a recent study showed a 45 day course of rivaroxaban 10mg was noninferior to fondaparinux at preventing serious complications in high risk SVT.

Resources

• CHEST Guidelines
• Prevention of thromboembolic complications in patients with superficial-vein thrombosis given rivaroxaban or fondaparinux.

Literature suggests patients who have experienced warfarin associated GIB, the benefits of resuming anticoagulant therapy will outweigh the risks (RETREAT). While the data varies as to exactly when anticoagulation should be restarted, available evidence indicates that waiting ∼14 days may best balance the risk of recurrent bleeding, thromboembolism, and mortality after gastrointestinal tract bleeding (WITT ASH Education Book December 2, 2016 vol. 2016 no. 1 620-624).

Resources

• Reply to “When to resume anticoagulation after acute gastrointestinal bleeding?”
• Thromboembolic events, recurrent bleeding and mortality after resuming anticoagulant following gastrointestinal bleeding
• What to do after the bleed