Direct-acting oral anticoagulants (DOACs), including apixaban, rivaroxaban, edoxaban, and dabigatran, are widely used for various indications and considered first-line therapy for prevention of acute ischemic stroke in patients with nonvalvular atrial fibrillation . The management of acute ischemic stroke in patients on DOACs presents a difficult clinical scenario in the emergency department due to concern for increased risk of hemorrhage. IV thrombolytics (e.g., alteplase, tenecteplase), a mainstay in acute ischemic stroke management, are not recommended in current guidelines for patients whose last DOAC dose was within the last 48 hours [2, 3]. Therefore, patients with an acute ischemic stroke who are compliant with their DOACs are often excluded from guideline recommended therapy. Additionally, as covered in a previous ALiEM post, it is not recommended to reverse anticoagulation status in order to administer a thrombolytic.
The use of IV thrombolytics in patients on DOACs was evaluated by Kam et al in a 2022 study published in JAMA . This retrospective analysis included 163,038 patients from the AHA/ASA Get With The Guidelines-Stroke registry with acute ischemic stroke who received IV alteplase within 4.5 hours of symptom onset. Of the total number of patients, only 2207 had documented use of a DOAC within the last 7 days, with 25 of these patients reporting DOAC use within 48 hours. Patients on warfarin or other anticoagulants were excluded. The primary outcome was symptomatic intracranial hemorrhage (ICH) within 36 hours of IV alteplase administration. After adjusting for clinical factors, the rate of symptomatic ICH was not significantly different between patients taking DOACs and those not on anticoagulation (3.7% vs. 3.2%, adjusted OR 0.88, 95% CI 0.70 to 1.10). However, when stratified based on time from last DOAC dose, patients who took their DOAC 0-48 hours prior had an 8% rate of symptomatic ICH compared to 3.2% among those not on DOACs. Furthermore, the rate of any alteplase complication was 12% vs. 6% in those taking DOACs within 48 hours vs. no DOAC.
- The population at highest risk for bleeding is patients who took a DOAC within the last 48 hours, and this study only included 25 such patients.
- A similar study tried to answer the same question for warfarin patients with an INR between 1.5-1.7. They also failed to include enough patients to make any definitive conclusions. 
- Timing from the last DOAC dose was given as a range, with the majority of patients reporting use sometime within the last 7 days. It has been established in current AHA/ASA guidelines that receipt of DOACs past 48 hours prior is considered safe for thrombolytic administration, and if the included institutions were following current recommendations, thrombolytics were likely administered mostly to patients outside the 48-hour window.
- Large potential for selection bias, since it was reported that almost 23,000 patients on DOACs from the original registry (who were otherwise eligible) did not receive thrombolytics.
- Not clear how patients were determined to be on DOACs or if the authors were able to confirm this in unresponsive/intubated/deceased patients retrospectively. This could have resulted in DOAC patients being included in the non-DOAC group, which could have falsely evened-out the bleeding rates.
- The management of acute ischemic stroke in patients receiving prior anticoagulation presents a challenging clinical scenario.
- Studies to date fail to include enough patients to evaluate the true risk of bleeding.
- This study supports the current guideline recommendation to avoid alteplase in patients receiving a DOAC within 0-48 hours due to the increased risk of intracranial hemorrhage.
Want to learn more about EM Pharmacology?
- January CT, Wann LS, Calkins H, et al. 2019 AHA/ACC/HRS focused update of the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation. Published correction appears in Circulation. 2019;140(6):e285. Circulation. 2019;140(2):e125-e151. doi: 10.1161/CIR.0000000000000665. PMID: 30686041.
- Powers WJ, Rabinstein AA, Ackerson T, et al. Guidelines for the early management of patients with acute ischemic stroke: 2019 update to the 2018 guidelines for the early management of acute ischemic stroke: a guideline for healthcare professionals from the American Heart Association/American Stroke Association. Stroke. 2019;50(12):e344-e418. doi: 10.1161/STR.0000000000000211. PMID: 31662037.
- Berge E, Whiteley W, Audebert H, et al. European Stroke Organisation (ESO) guidelines on intravenous thrombolysis for acute ischaemic stroke. Eur Stroke J. 2021;6(1):I-LXII. doi: 10.1177/2396987321989865. PMID: 33817340.
- Kam W, Holmes DN, Hernandez AF, et al. Association of Recent Use of Non-Vitamin K Antagonist Oral Anticoagulants With Intracranial Hemorrhage Among Patients With Acute Ischemic Stroke Treated With Alteplase. JAMA. 2022;327(8):760-771. doi:10.1001/jama.2022.0948. doi: 10.1001/jama.2022.0948. PMID: 35143601.
- Xian Y, Liang L, Smith EE, et al. Risks of intracranial hemorrhage among patients with acute ischemic stroke receiving warfarin and treated with intravenous tissue plasminogen activator. JAMA. 2012;307(24):2600-2608. doi:10.1001/jama.2012.6756. doi: 10.1001/jama.2012.6756. PMID: 22735429.
Jessica Mason, PharmD
PGY-2 Emergency Medicine Pharmacy Resident
Massachusetts General Hospital
Bleeding patients or those undergoing procedures that are at high risk of bleeding may require correction of their INR. Multiple products can be used to achieve this, including fresh frozen plasma (FFP). FFP contains many substances, including clotting factors, fibrinogen, plasma proteins, electrolytes, and anticoagulant factors. It is sometimes said that the intrinsic INR of FFP is approximately 1.6-1.7 and that it’s not possible to achieve a lower INR. This pearl will further explore these concerns.
- What is the INR of FFP?
- The mean INR of FFP appears to be ~1.1 (0.9-1.3) [1,2].
- Reports that the intrinsic INR of FFP is 1.6-1.7 may be based on the clinical experience of not being able to achieve an INR <1.6-1.7 with FFP.
- Is it possible to “normalize” the INR with FFP alone?
- Several studies have found that it’s difficult to achieve an INR <1.7 with only FFP [3,4]. However, other studies were able to achieve lower average INR values [2,5,6].
- Overall, these studies found that there was a significantly greater decrease in INR when the pre-FFP INR was higher, but there was a much smaller decrease when the INR was closer to the normal range.
- Why does FFP appear to have diminishing returns when the pre-FFP INR is lower?
- The relationship between the INR and percentage of clotting factors present in the blood is not linear (see figure) .
- For example: An increase of ~5% in clotting factors may decrease the INR from 3 to 2.5 but the same amount of FFP may only reduce an INR of 1.7 to 1.6.
Figure 1: Adapted from Dzik 2012 .
- Additionally, the table below also demonstrates that small volumes of FFP result in large changes when the initial INR is elevated, but very large amounts of FFP are required to achieve an INR of 1.3 no matter the initial INR (see table).
|Amount of FFP to Achieve a Target INR Based on Pre-FFP INR|
|Initial INR||Volume (L)||Dose (mL/kg)||Factor (%)||Volume (L)||Dose (mL/kg)||Factor (%)||Volume (L)||Dose (mL/kg)||Factor (%)|
Table 1: Adapted from Holland 2006 . Note: 1 unit of FFP is ~200-250 mL
- Given the above data, the issue preventing the achievement of an INR <1.7 appears to be the dose/volume of FFP required and not the intrinsic INR of FFP.
- Does the INR need to be <1.7 to achieve hemostasis?
- Since the INR only provides limited information regarding a single aspect of anticoagulation status, complete normalization for the INR to control bleeding is usually not necessary .
- An INR elevation alone does not indicate a patient is coagulopathic or at an increased risk of bleeding . Additionally, an INR elevation in patients with liver dysfunction likely reflects an overall state of decreased factor production, both procoagulant and anticoagulant factors .
- The target INR varies depending on multiple patient factors and planned interventions, but an INR of 1.0 is likely not necessary to prevent bleeding or achieve hemostasis.
- A unit of FFP has an INR of ~1.1, but this doesn’t mean it can easily normalize the INR.
- There is a non-linear relationship between percentage of clotting factors and the INR, resulting in diminishing returns from each unit of FFP as the INR decreases.
- Very large doses of FFP may be required to fully correct an elevated INR, which frequently precludes its use.
- Complete normalization of the INR is not required to achieve hemostasis or prevent bleeding from a procedure.
Want to learn more about EM Pharmacology?
- Holland LL, Foster TM, Marlar RA, Brooks JP. Fresh frozen plasma is ineffective for correcting minimally elevated international normalized ratios. Transfusion. 2005;45(7):1234-1235. doi: 10.1111/j.1537-2995.2005.00184.x. PMID: 15987373.
- Only AJ, DeChristopher PJ, Iqal O, Fareed J. Restoration of normal prothrombin time/international normalized ratio with fresh frozen plasma in hypocoagulable patients. Clin Appl Thromb Hemost. 2016;22(1):85-91. doi: 10.1177/1076029614550819. PMID: 25294634.
- Holland LL, Brooks JP. Toward rational fresh frozen plasma transfusion: The effect of plasma transfusion on coagulation test results. Am J Clin Pathol. 2006;126(1):133-139. doi: 10.1309/NQXH-UG7H-ND78-LFFK. PMID: 16753596.
- Abdel-Wahab OI, Healy B, Dzik WH. Effect of fresh-frozen plasma transfusion on prothrombin time and bleeding in patients with mild coagulation abnormalities. Transfusion. 2006;46(8):1279-1285. doi: 10.1111/j.1537-2995.2006.00891.x. PMID: 16934060.
- Müller MCA, Straat M, Meijers JCM, et al. Fresh frozen plasma transfusion fails to influence the hemostatic balance in critically ill patients with a coagulopathy. J Thromb Haemost. 2015;13(6):989-997. doi: 10.1111/jth.12908. PMID: 25809519.
- McCully SP, Fabricant LJ, Kunio NR, et al. The International Normalized Ratio overestimates coagulopathy in stable trauma and surgical patients. J Trauma Acute Care Surg. 2013;75(6):947-953. doi: 10.1097/TA.0b013e3182a9676c. PMID: 24256665.
- Dzik W “Sunny.” Reversal of drug-induced anticoagulation: old solutions and new problems. Transfusion. 2012;52(s1):45S-55S. doi: 10.1111/j.1537-2995.2012.03690.x. PMID: 22578371.
- Harrison MF. The misunderstood coagulopathy of liver disease: a review for the acute setting. West J Emerg Med. 2018;19(5):863-871. doi: 10.5811/westjem.2018.7.37893. PMID: 30202500.