Short-term warfarin reversal for elective surgery - using low-dose intravenous vitamin K: safe, reliable and convenient*

Controversies in Stoppage of Antiplatelet and Anticoagulant Medications Prior to Oral Surgery

Dental procedures can pose a risk of bleeding, and it is not uncommon for dentists to consult prescribing physicians regarding a mutual patient's antiplatelet and anticoagulant medication to prevent excessive bleeding during or after an upcoming procedure. However, there has been a growing controversy in the dental community surrounding the stoppage of these medications prior to dental procedures. Some believe that stopping these medications prior to dental procedures is necessary to reduce the risk of bleeding complications, while others argue that stopping them can increase the risk of stroke or other thromboembolic events. The debate has left many dentists and specialists unsure about the best course of action when it comes to managing bleeding risk during dental procedures.In this article, we will review the antithrombotic medications, indications, mechanism of action, and its effects on the coagulation pathway, laboratory testing and reversal agents. Also, we will explore the controversy surrounding the stoppage of novel anitplatelets (eg,: prasurgrel and ticagrelor), dual-antiplatelets, triple-antiplatelet, vitamin K antagonists (eg,: wafarin, coumadin), and direct oral anticoagulants (eg,: dabigatran, rivaroxaban, xarelto and endoxaban) in dentistry and examine the current evidence and guidelines for managing dental patients undergoing oral surgery.

Blasting the myth of predictive INR changes related to plasma transfusion: an academic institution's experience

INTRODUCTION

Plasma transfusion is a common therapeutic strategy used to lower international normalized ratio (INR) values in the non-emergent setting. However, due to lack of evidence of its efficacy, standardized guidelines for this practice have not been well established.

METHODS

This retrospective observational cohort study analyzed 276 inpatient encounters that involved plasma transfusions focusing on change in INR values from pre- to post-transfusion, with respect to the following predictor variables: vitamin K co-administration, number of plasma units transfused, order indication and body mass index (BMI).

RESULTS

The overall average change in the INR was 1.35. Patients who received vitamin K showed an average change of 2.51, while patients that did not receive vitamin K demonstrated an average change of 0.70. Increased numbers of plasma units transfused showed benefit up to three-unit orders. Greater decreases in the INR were observed for patients requiring plasma for anticoagulation reversal or active bleeding. There was no significant difference in the change in INR based on the BMI. By multivariate and regression analyses, the stepwise addition of each successive predictor variable demonstrated an increase in the shared variance in the outcome of the post-transfusion INR: the pre-transfusion INR and vitamin K co-administration alone was not significant (p = 0.45); the additional number of plasma units transfused was significant (R² = 0.13, p < 0.001), and; the subsequent additional plasma order indications (R² = 0.19, p < 0.001) and BMI (R² = 0.18, p < 0.001) were increasingly significant.

CONCLUSION

Taking into consideration the combination of multiple predictive factors may aid in a more efficient use of plasma products.

Methods to Correct Drug-Induced Coagulopathy in Bleeding Emergencies: A Comparative Review

OBJECTIVE

Anticoagulant and antiplatelet therapy have become increasingly popular. The goal of therapy is to prevent venous thromboembolism and platelet aggregation, respectively. Traditional anticoagulant and antiplatelet drugs are quickly being replaced with novel medications with more predictable pharmacokinetics. Unfortunately, these drugs carry the risk of uncontrolled hemorrhage because of drug-induced coagulopathy. Uncontrolled hemorrhage continues to be a major cause of preventable death: hemorrhage accounts for approximately 30% of trauma-related deaths, second to brain injury. Controlling hemorrhage while dealing with comorbidities remains a challenge to clinicians. There are many gaps in care and knowledge that contribute to the struggle of treating this patient population.

METHODS

This literature review is focused on the most effective ways to achieve hemostasis in a patient with drug-induced coagulopathy. The antiplatelet therapies aspirin, clopidogrel, ticlopidine, pasugrel, and ticagrelor are analyzed. Anticoagulant therapies are also reviewed, including warfarin, rivaroxaban, apixaban, edoxaban, and dabigatran. In addition, viscoelastic testing and platelet function assays are reviewed for their ability to monitor drug effectiveness and to accurately depict the patient's ability to clot. This review focuses on articles from the past 10 years. However, there are limitations to the 10-year restriction, including no new research posted within the 10-year timeline on particular subjects. The most recent article was then used where current literature did not exist (within 10 years).

RESULTS

Traditional anticoagulants have unpredictable pharmacokinetics and can be difficult to correct in bleeding emergencies. Vitamin K has been proven to reliably and effectively reverse the effect of vitamin K antagonists (VKAs) while having a lower anaphylactoid risk than frozen plasma. Prothrombin complex concentrates should be used when there is risk of loss of life or limb. Frozen plasma is not recommended as a first-line treatment for the reversal of VKAs. Novel anticoagulants have specific reversal agents such as idarucizumab for dabigatran and andexxa alfa for factor Xa (FXa) inhibitors. Although reliable, these drugs carry a large price tag. As with traditional anticoagulants, cheaper alternative therapies are available such as prothrombin complex concentrates. Finally, static coagulation testing works well for routine therapeutic drug monitoring but may not be appropriate during bleeding emergencies. Viscoelastic testing such as thromboelastography and rotational thromboelastometry depict in vivo hemostatic properties more accurately than static coagulation assays. Adding viscoelastic testing into resuscitation protocols may guide blood product usage more efficiently.

CONCLUSION

This review is intended to be used as a guide. The topics covered in this review should be used as a reference for treating the conditions described. This review article also covers laboratory testing and is meant as a guide for physicians on best practices. These findings illustrate recommended testing and reversal techniques based off evidence-based medicine and literature.

Pharmacometric modeling to explore 4F-PCC dosing strategies for VKA reversal in patients with INR below 2

The indicated dose of 4-factor prothrombin complex concentrate (4F-PCC) for urgent vitamin K antagonist (VKA) reversal in patients with an international normalized ratio (INR) of 2 to 4 is 25 IU/kg, but there is no indicated dose for INR <2. We explored 4F-PCC dosing strategies for baseline INR <2. Clinical trial data were used to develop pharmacometric models for Factor X (FX) and FII, accounting for covariates including baseline INR. FX and FII levels over time were simulated for mean baseline INR levels of the clinical trial participants plus baseline INRs 3.1, 1.9, and 1.6. For each INR, 200 virtual male patients were simulated to evaluate 4F-PCC doses of 35, 25, 20, 15, 12.5, and 10 IU/kg. Given an elevated bleeding risk with VKA therapy in Japanese vs Western populations, results were stratified by Japanese and non-Japanese patients. Target levels of FX and FII were ≥50% activity at 30 minutes after dosing in ≥80% of patients. FX- and FII-time models were developed with 1088 FX observations from 193 patients and 1074 FII observations from 192 patients. Model-based simulations indicated that at baseline INR 3.1, ≥80% of patients achieved ≥50% FX and FII activity with 25 IU/kg and 20 IU/kg 4F-PCC, respectively; at baseline INR 1.9, corresponding doses were 20 IU/kg and 15 IU/kg 4F-PCC, and at baseline INR 1.6, corresponding doses were 15 IU/kg, and 10 IU/kg 4F-PCC. Trends in Japanese and non-Japanese patients were similar. In conclusion, low 4F-PCC doses (15-20 IU/kg) may be sufficient to achieve hemostatic levels of FX and FII in Japanese and non-Japanese patients with baseline INR <2.

Clinical protocols for oral anticoagulant reversal during high risk of bleeding for emergency surgical and nonsurgical settings: a narrative review

Background and objectives

Oral anticoagulants prevent thromboembolic events but expose patients to a significant risk of bleeding due to the treatment itself, after trauma, or during surgery. Any physician working in the emergency department or involved in the perioperative care of a patient should be aware of the best reversal approach according to the type of drug and the patient’s clinical condition. This paper presents a concise review and proposes clinical protocols for the reversal of oral anticoagulants in emergency settings, such as bleeding or surgery.

Contents

The authors searched for relevant studies in PubMed, LILACS, and the Cochrane Library database and identified 82 articles published up to September 2020 to generate a review and algorithms as clinical protocols for practical use. Hemodynamic status and the implementation of general supportive measures should be the first approach under emergency conditions. The drug type, dose, time of last intake, and laboratory evaluations of anticoagulant activity and renal function provide an estimation of drug clearance and should be taken into consideration. The reversal agents for vitamin K antagonists are 4-factor prothrombin complex concentrate and vitamin K, followed by fresh frozen plasma as a second-line treatment. Direct oral anticoagulants have specific reversal agents, such as andexanet alfa and idarucizumab, but are not widely available. Another possibility in this situation, but with less evidence, is prothrombin complex concentrates.

Conclusion

The present algorithms propose a tool to help healthcare providers in the best decision making for patients under emergency conditions.

Proximal femur fractures in patients taking anticoagulants

Thirty per cent of patients presenting with proximal femoral fractures are receiving anticoagulant treatment for various other medical reasons. This pharmacological effect may necessitate reversal prior to surgical intervention to avoid interference with anaesthesia or excessive peri/post-operative bleeding. Consequently, delay to surgery usually occurs.

Platelet inhibitors (aspirin, clopidogrel) either alone or combined do not need to be discontinued to allow acute hip surgery. Platelet transfusions can be useful but are rarely needed.

Vitamin K antagonists (VKA, e.g. warfarin) should be reversed in a timely fashion and according to established readily accessible departmental protocols. Intravenous vitamin K on admission facilitates reliable reversal, and platelet complex concentrate (PCC) should be reserved for extreme scenarios.

Direct oral anticoagulants (DOAC) must be discontinued prior to hip fracture surgery but the length of time depends on renal function ranging traditionally from two to four days.

Recent evidence suggests that early surgery (within 48 hours) can be safe. No bridging therapy is generally recommended.

There is an urgent need for development of new commonly available antidotes for every DOAC as well as high-level evidence exploring DOAC effects in the acute hip fracture surgical setting.

Cite this article: EFORT Open Rev 2020;5:699-706. DOI: 10.1302/2058-5241.5.190071

Coagulation in liver surgery: an observational haemostatic profile and thromboelastography study

BACKGROUND

International normalized ratio (INR) is used as a marker of the haemostatic status following liver resection. However, the impact of liver resection on haemostasis is complex and beyond what can be measured by INR. This study aimed to prospectively assess haemostatic profile following liver resection and determine if INR measurement can safely guide post-operative thromboprophylaxis.

METHODS

In this prospective cohort study, patients undergoing liver resection had coagulation parameters (International normalised ratio (INR), prothrombin time (PT), activated partial thromboplastin time, fibrinogen, d-dimer, von Willebrand factor antigen, procoagulant activity of phospholipids and clotting factors II, VII, VIIIc, IX and X) and thromboelastogram parameters assessed perioperatively. Clinical follow-up assessed for thromboembolism and haemorrhage.

RESULTS

In the 41 patients included, INR was significantly (P < 0.0001) elevated post-operatively, and INR >1.5 was observed in seven of 41 (17.1%) on post-operative day 1 and one of 41 (2.4%) patients on post-operative day 3, respectively. Factor VII levels showed transient reduction but other factors, especially factors II and X, remained within normal range following liver resection. Thromboelastogram parameters remained normal or supranormal for all patients at all time points. One incident of post-hepatectomy haemorrhage occurred, despite a normal coagulation profile. Two patients suffered late pulmonary embolic episodes.

CONCLUSION

Post liver resection haemostasis is complex and poorly reflected by INR, which should not guide initiation of chemical thromboprophylaxis in the immediate post-operative period.

Revisiting the International Normalized Ratio Threshold for Bleeding Risk and Mortality in Primary Total Hip Arthroplasty: A National Surgical Quality Improvement Program Analysis of 17,567 Patients

BACKGROUND

Efforts to identify preoperative risk factors for primary total hip arthroplasty have amplified with its increasing incidence. The international normalized ratio (INR) is 1 measure that may influence postoperative outcomes. This study of a national database assessed whether there exists an association between preoperative INR and postoperative bleeding and mortality among patients who underwent primary total hip arthroplasty.

METHODS

We retrospectively analyzed 17,567 adult patients who underwent primary total hip arthroplasty in the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) between 2005 and 2016. Patients were stratified by preoperative INR into 4 groups: INR <1.0, 1.0 to <1.25, 1.25 to <1.5, and ≥1.5. Bleeding necessitating transfusion was the primary outcome, and secondary outcomes included mortality, infection, and readmission. Multivariable logistic regressions controlled for baseline differences.

RESULTS

Among the patients who underwent total hip arthroplasty, 20.5% had INR <1.0, 73.6% had INR 1.0 to <1.25, 4.2% had INR 1.25 to <1.5, and 1.8% had INR ≥1.5. Mortality increased incrementally from 0.3% for INR <1.0 to 4.9% for INR ≥1.5 (p < 0.001), and bleeding risk increased from 13.2% for INR <1.0 to 29.3% for INR ≥1.5 (p < 0.001). After adjustment, bleeding risk was increased for INR 1.25 to <1.5 (odds ratio [OR], 1.55 [95% confidence interval (CI), 1.26 to 1.92]) and INR ≥1.5 (OR, 1.55 [95% CI, 1.15 to 2.08]) compared with INR <1.0. The only group associated with increased mortality was INR ≥1.5 (OR, 2.69 [95% CI, 1.07 to 6.76]). The length of stay significantly increased with increasing INR, from 3.6 to 6.3 days (p < 0.001).

CONCLUSIONS

This study found a significant, independent effect between increased preoperative INR and increased bleeding and mortality. Bleeding risk becomes evident at INR ≥1.25, and those patients with INR ≥1.5 are at significantly increased risk of mortality.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Risk Factors for Postoperative Intracranial Hemorrhage After Resection of Intracranial Tumor in 2259 Consecutive Patients

BACKGROUND

Postoperative hemorrhage (POH), an uncommon complication after cranial operation, may result in prolonged postoperative hospitalization, severe neurologic impairment, or even death. Most models in studies detecting risk factors for POH include all kinds of cranial lesions; however, factors associated with POH may vary among intracranial diseases. There is a paucity of large sample studies focusing solely on POH after intracranial tumor surgery. Therefore, this study was designed to investigate the preoperative risk factors for POH after surgery for intracranial tumor.

METHODS

Medical records of 2259 adult patients who underwent primary surgical resection of single intracranial tumor between January 2017 and June 2018 at West China Hospital of Sichuan University were retrospectively studied. Univariate and multivariate analyses were performed to identify the risk factors for POH after resection of intracranial tumor.

RESULTS

POH (defined as postoperative hematoma requiring surgical evacuation) occurred in 40 of 2259 patients (1.8%). Univariate analysis revealed that older age (P = 0.037, Wilcoxon-Mann-Whitney test), higher international normalized ratio (INR) (P = 0.037, Wilcoxon-Mann-Whitney test), and larger tumor size (P = 0.001, Wilcoxon-Mann-Whitney test) were significantly associated with POH. Then it was confirmed by multivariate analysis that all of the 3 factors (older age: P = 0.033, higher INR: P = 0.044, larger tumor size: P = 0.002) were independent risk factors for POH after removal of intracranial tumor.

CONCLUSIONS

Older age, higher INR, and larger tumor size were identified as independent risk factors for POH after resection of intracranial tumor in adults.

Periprocedural Bridging in Patients with Venous Thromboembolism: A Systematic Review

BACKGROUND

Vitamin K antagonists (VKA) are the most widely used anticoagulants, and bridging is commonly administered during periprocedural VKA interruption. Given the unclear benefits and risks of periprocedural bridging in patients with previous venous thromboembolism, we aimed to assess recurrent venous thromboembolism and bleeding outcomes with and without bridging in this population.

METHODS

We performed a systematic review searching the PubMed and Embase databases from inception to December 7, 2017 for randomized and nonrandomized studies that included adults with previous venous thromboembolism requiring VKA interruption to undergo an elective procedure, and that reported venous thromboembolism or bleeding outcomes. Quality of evidence was graded by consensus.

RESULTS

We included 28 cohort studies (20 being single-arm cohorts) with, overall, 6915 procedures for analysis. In 27 studies reporting perioperative venous thromboembolism outcomes, the pooled incidence of recurrent venous thromboembolism with bridging was 0.7% (95% confidence interval [CI], 0.4%-1.2%) and 0.5% (95% CI, 0.3%-0.8%) without bridging. Eighteen studies reported major or nonmajor bleeding outcomes. The pooled incidence of any bleeding was 3.9% (95% CI, 2.0%-7.4%) with bridging and 0.4% (95% CI, 0.1%-1.7%) without bridging. In bridged patients at high thromboembolic risk, the pooled incidence for venous thromboembolism was 0.8% (95% CI, 0.3%-2.5%) and 7.5% (95% CI, 3.1%-17.4%) for any bleeding. Quality of available evidence was very low, primarily due to a high risk of bias of included studies.

CONCLUSIONS

Periprocedural bridging increases the risk of bleeding compared with VKA interruption without bridging, without a significant difference in periprocedural venous thromboembolism rates.

Revisiting the International Normalized Ratio (INR) Threshold for Complications in Primary Total Knee Arthroplasty: An Analysis of 21,239 Cases

BACKGROUND

Consensus guidelines recommend use of the international normalized ratio (INR) to predict the risk of perioperative bleeding in orthopaedic surgery. However, current recommendations for targeting an INR of <1.5 are based on studies across all surgical disciplines. This study examined the impact of the INR on perioperative bleeding, mortality, postoperative infections, length of hospital stay (LOS), and readmissions following primary total knee arthroplasty (TKA).

METHODS

We retrospectively reviewed the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database for adult patients who underwent primary TKA from 2010 to 2016. Patients for whom an INR had been recorded within 1 day before the surgery were stratified and analyzed for perioperative bleeding, mortality within 30 days, deep wound and superficial infections, LOS, and readmissions. Multivariable regressions were utilized to adjust for differences in demographics and comorbidities among INR groups.

RESULTS

Of 21,239 patients, 57.2% had an INR of ≤1.0; 38.1% had an INR of >1.0 to 1.25, 3.9% had an INR of >1.25 to 1.5, and 0.8% had an INR of >1.5. After adjustment, a progressively increased bleeding risk was found with an INR of >1.0 to 1.25 (odds ratio [OR] = 1.19, 95% confidence interval [CI] = 1.07 to 1.31, p = 0.001), an INR of >1.25 to 1.5 (OR = 1.29, 95% CI = 1.02 to 1.63, p = 0.033), and an INR of >1.5 (OR = 2.02, 95% CI = 1.29 to 3.14, p = 0.002) relative to an INR of ≤1.0. Patients with an INR of >1.5 were at increased risk for infection (OR = 5.34, 95% CI = 2.45 to 11.68, p < 0.001), but only patients with an INR of >1.25 to 1.5 were at increased risk for mortality (OR = 3.37, 95% CI = 1.31 to 8.63, p = 0.011) relative to those with an INR of ≤1.0. Overall and TKA-related readmission rates and LOS were significantly increased for patients with an INR of >1.25 to 1.5 or an INR of >1.5.

CONCLUSIONS

An INR of >1.25 to 1.5 was associated with increased bleeding, infection, and mortality rates following TKA, and an INR of >1.5 was associated with increased bleeding and infection rates. Current INR target recommendations in consensus guidelines should be reconsidered.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Vitamin K: Double Bonds beyond Coagulation Insights into Differences between Vitamin K1 and K2 in Health and Disease

Vitamin K is an essential bioactive compound required for optimal body function. Vitamin K can be present in various isoforms, distinguishable by two main structures, namely, phylloquinone (K1) and menaquinones (K2). The difference in structure between K1 and K2 is seen in different absorption rates, tissue distribution, and bioavailability. Although differing in structure, both act as cofactor for the enzyme gamma-glutamylcarboxylase, encompassing both hepatic and extrahepatic activity. Only carboxylated proteins are active and promote a health profile like hemostasis. Furthermore, vitamin K2 in the form of MK-7 has been shown to be a bioactive compound in regulating osteoporosis, atherosclerosis, cancer and inflammatory diseases without risk of negative side effects or overdosing. This review is the first to highlight differences between isoforms vitamin K1 and K2 by means of source, function, and extrahepatic activity.

Effect of vitamin K administration on rate of warfarin reversal

BACKGROUND

Vitamin K is reported to begin reversing warfarin within 6 to 12 hours, but this may occur sooner. We sought to determine the rate of international normalized ratio (INR) reversal following vitamin K and relationships with dose, route, and baseline INR.

METHODS

We evaluated adult patients receiving vitamin K monotherapy for warfarin reversal. Post-vitamin K INRs through 48 hours were collected. Relationships between vitamin K dose and route and baseline INR on rate of reversal and complete reversal (INR < 1.5) were evaluated. Assessment was performed graphically using scatter plots with a line of best fit and a counting process model to determine variables associated with achieving complete reversal.

RESULTS

A total of 469 post-vitamin K INRs from 235 patients were included. Time to first INR follow-up after vitamin K administration averaged 10.5 ± 4.2 hours. A significant decrease was detected in INR values in comparison to the baseline INR (3.0 ± 1.9 vs. 4.7 ± 2.2; p < 0.01). Rapid and steady INR change began immediately after vitamin K administration (0-4 hr). A high vitamin K dose and intravenous route were associated with rapid INR change and complete reversal (Vitamin K 10 mg [hazard ratio, 2.4; 95% confidence interval, 1.4-4.2] and IV route [hazard ratio, 1.8; 95% confidence interval, 1.3-2.6]); however, overall complete reversal at 24 and 48 hours was low (14.5% and 41.7%, respectively). Higher baseline INR was associated with rapid INR change and lower baseline INR with complete reversal.

CONCLUSION

Vitamin K alone starts to reverse warfarin immediately. High vitamin K doses and intravenous route are associated with faster INR reversal. Baseline INR also influences rate of correction and frequency of achieving complete reversal.

Elevated International Normalized Ratio Is Not Associated With Increased Perioperative Morbidity in Podiatric Limb Salvage Surgery: A Retrospective Analysis

The risk of hemorrhage always exists in anticoagulated patients with an elevated international normalized ratio (INR), a risk that must be measured against the necessity for surgical procedures. The objective of the present retrospective medical record study was to assess the safety with which limb salvage procedures can be conducted in patients with an INR >1.4. The medical records of 231 patients who had undergone limb salvage procedures by 1 surgeon at the Yale New Haven Health System from November 2008 through July 2014 were reviewed. All patients were administered foot blocks with monitored intravenous sedation. The patients' demographic data, comorbidities, preoperative anticoagulant use, coagulation profile, intraoperative analgesic administration, estimated blood loss, total operating room time, total postanesthesia care unit time, intraoperative ankle tourniquet use, and postoperative complications within the initial 72 hours were reviewed. We found no differences in intraoperative bleeding, total intraoperative time, or recovery time between the INR <1.4 group (n = 212) and the INR >1.4 group (n = 19). None of the patients experienced any postoperative complications, defined as any cardiac or pulmonary event, the need for invasive monitoring, or admission to the intensive care unit within the initial 72-hour period. Our findings suggest that patients are suitable for undergoing peripheral procedures with foot blocks and monitored intravenous sedation even in the presence of an elevated INR.

Management of anticoagulation in hip fractures: A pragmatic approach

Hip fractures are common and increasing with an ageing population. In the United Kingdom, the national guidelines recommend operative intervention within 36 hours of diagnosis. However, long-term anticoagulant treatment is frequently encountered in these patients which can delay surgical intervention. Despite this, there are no set national standards for management of drug-induced coagulopathy pre-operatively in the context of hip fractures.

The aim of this study was to evaluate the management protocols available in the current literature for the commonly encountered coagulopathy-inducing agents.

We reviewed the current literature, identified the reversal agents used in coagulopathy management and assessed the evidence to determine the optimal timing, doses and routes of administration.

Warfarin and other vitamin K antagonists (VKA) can be reversed effectively using vitamin K with a dose in the range of 2 mg to 10 mg intravenously to correct coagulopathy.

The role of fresh frozen plasma is not clear from the current evidence while prothrombin complex remains a reliable and safe method for immediate reversal of VKA-induced coagulopathy in hip fracture surgery or failed vitamin K treatment reversal.

The literature suggests that surgery should not be delayed in patients on classical antiplatelet medications (aspirin or clopidogrel), but spinal or regional anaesthetic methods should be avoided for the latter. However, evidence regarding the use of more novel antiplatelet medications (e.g. ticagrelor) and direct oral anticoagulants remains a largely unexplored area in the context of hip fracture surgery. We suggest treatment protocols based on best available evidence and guidance from allied specialties.

Hip fracture surgery presents a common management dilemma where semi-urgent surgery is required. In this article, we advocate an evidence-based algorithm as a guide for managing these anticoagulated patients.

Cite this article: EFORT Open Rev 2017;2:394–402. DOI: 10.1302/2058-5241.2.160083

Fast-track rapid warfarin reversal for elective surgery: extending the efficacy profile to high-risk patients with cancer

Periprocedural management of patients on long-term warfarin therapy remains a common and important clinical issue, with little high-quality data to guide this complex process. The current accepted practice is cessation of warfarin five days preoperatively, but this is not without risk and can be complicated, particularly if bridging is required. An alternative method utilising low-dose intravenous vitamin K the day before surgery has been shown previously to be efficacious, safe and convenient in an elective surgical population receiving chronic warfarin therapy. The efficacy and utility of this 'fast-track' warfarin reversal protocol in surgical patients with cancer, who were at high risk of both thromboembolism and bleeding was investigated in a prospective, single-arm study at a dedicated cancer centre. Seventy-one patients underwent 82 episodes of fast-track warfarin reversal (3 mg intravenous vitamin K 18 to 24 hours before surgery). No patient suffered an adverse reaction to intravenous vitamin K, all but one achieved an International Normalized Ratio =1.5 on the day of surgery, and no surgery was deferred. Assays of vitamin K-dependent factor levels pre- and post-vitamin K demonstrated restoration of functional activity to within an acceptable range for surgical haemostasis. While this alternative method requires further validation in a larger prospective randomised study, we have now extended our use of fast-track warfarin reversal using vitamin K to patients with cancer, on the basis of our experience of its safety, convenience, reliability and efficacy.

Budget impact analysis of warfarin reversal therapies among hip fracture patients in Finland

BACKGROUND

Hip fractures require operation within 36-48 h, and they are most common in the elderly. A high International Normalized Ratio should be corrected before surgery. In the current study, we analyzed the budget impact of various warfarin reversal approaches.

METHODS

Four reversal strategies were chosen for the budget impact analysis: the temporary withholding of warfarin, administration of vitamin K, fresh frozen plasma (FFP), and a four-factor prothrombin complex concentrate (PCC).

RESULTS

We estimated that, annually, 410 hip fracture patients potentially require warfarin reversal in Finland. The least costly treatment was vitamin K, which accounted for €289,000 in direct healthcare costs, and the most costly treatment option was warfarin cessation, which accounted for €1,157,000. In the budget impact analysis, vitamin K, PCC and FFP would be cost-saving to healthcare compared with the current treatment mix.

CONCLUSION

The various warfarin reversal strategies have different onset times, which may substantially impact the subsequent healthcare costs.

Management of Anticoagulant and Antiplatelet Medications in Adults Undergoing Percutaneous Interventions

OBJECTIVE

Many radiologists are unfamiliar with the new antithrombogenic medications and how to modify patient management before nonvascular percutaneous procedures performed in a radiology department. In this article, we review the indications for use, mechanism of action, pharmacokinetics, dosing, and recommendations for periprocedural management of patients using these medications.

CONCLUSION

To improve patient safety, radiologists involved in percutaneous procedures should have knowledge of the antithrombotics that will be encountered routinely in clinical practice.

New strategies for effective treatment of vitamin K antagonist-associated bleeding

Vitamin K antagonists have been used as oral anticoagulants in the treatment and prevention of thromboembolic events for over half a century. Although vitamin K antagonists are effective in the management of thromboembolic events, the need for routine monitoring and the associated risk of bleeding has resulted in the development and licensing of direct oral anticoagulants for specific clinical indications. Despite these developments, vitamin K antagonists remain the oral anticoagulants of choice in many clinical conditions. Severe bleeding associated with oral anticoagulation requires urgent reversal. Several options for the reversal of vitamin K antagonist exist, including vitamin K, prothrombin complex concentrates and plasma. In this manuscript, we review current evidence and provide physicians with treatment strategies for more effective management of vitamin K antagonist-associated bleeding.

Preoperative warfarin reversal for early hip fracture surgery

PURPOSE

To evaluate our hospital protocol of low-dose vitamin K titration for preoperative warfarin reversal for early hip fracture surgery.

METHODS

Records of 16 men and 33 women aged 63 to 93 (mean, 81) years who were taking warfarin for atrial fibrillation (n=40), venous thromboembolism (n=9), cerebrovascular accident (n=3), and prosthetic heart valve (n=3) and underwent surgery for hip fractures were reviewed. The 3 patients with a prosthetic heart valve were deemed high risk for thromboembolism and the remainder low-risk. The international normalised ratio (INR) of patients was checked on admission and 6 hours after administration of vitamin K; an INR of <1.7 was considered safe for surgery.

RESULTS

No patient developed venous thromboembolism within one year. The 30-day and one-year mortality was 8.2% and 32.6%, respectively. For the 46 low-risk patients, the mean INR on admission was 2.6 (range, 1.1-4.6) and decreased to <1.7 after a mean of 2.2 (range, 0-4) administrations of 2 mg of vitamin K. Their INR was <1.7 within 18 hours (mean, 14 hours). 78% of patients underwent surgery within 36 hours. In the 22% of patients who did not undergo surgery within 36 hours, the delay was due to insufficient operative time or the patient being medically unfit for surgery. The 3 high-risk patients underwent bridging therapy of low-molecular-weight heparin and received no vitamin K; their mean INR on admission was 3.2 (range, 3.1-3.3) and the mean time to surgery was 5.3 (range, 3-8) days. Two low-risk patients and one high-risk patient died within 5 days of surgery.

CONCLUSION

The low-dose intravenous vitamin K protocol is safe and effective in reversing warfarin within 18 hours. Hip fracture surgery within 36 to 48 hours of admission improves morbidity and mortality.

The effect of preoperative vitamin K on the INR in bridging therapy

We investigated a bridging protocol using oral Vitamin K three days before scheduled surgery. 60 patients in two bridging protocols, 30 cases per protocol. The first cohort (Control group) had its warfarin held on Day-5 (five days before surgery). The intervention cohort (Vitamin K group) routinely received 2.5 mg of oral Vitamin K on Day-3 but was otherwise identically bridged. Primary outcome was INR on Day-1. Secondary outcomes included patients with INRs ≥1.5 on Day-1, bleeding episodes and elevated INR post surgery. Day-1 INR for the Vitamin K group was 1.16, vs. 1.28 for the Control group (p = 0.037). Postoperative INR was similar. Only the Control group had patients with INRs ≥1.5 on Day-1, or patients with significant bleeding. Adding Vitamin K on Day-3 leads to a safe preoperative INR and may limit other complications.

Management of bleeding and reversal strategies for oral anticoagulants: clinical practice considerations

PURPOSE

Currently available clinical data and optimal strategies for reversing oral anticoagulants in patients who are bleeding or need an urgent invasive procedure or operation are reviewed.

SUMMARY

Bleeding from oral anticoagulants, including new target-specific oral agents (TSOAs), is a common cause of morbidity and mortality, especially in elderly patients. Limited clinical data are available to guide the reversal of warfarin or TSOAs in patients who are bleeding or need an urgent invasive procedure or operation. A panel of five experts with diverse backgrounds in anticoagulation therapy, cardiology, critical care, and emergency medicine and with experience in managing complications of anticoagulation therapy was convened to develop practical strategies for managing patients receiving oral anticoagulants who are bleeding or have an urgent need for an invasive procedure. The strategies were designed to guide clinicians in the acute care setting by providing efficient and potentially effective management concepts to avoid delays in initiating treatment that could adversely affect patient outcomes. The consensus of this expert panel is summarized herein. Recommendations are based on currently available evidence from a comprehensive review of the literature and other pertinent data, along with the experience and expert opinion of the panelists.

CONCLUSION

Bleeding is a serious complication of the use of oral anticoagulants, and limited information is available to guide the reversal of warfarin or TSOAs in patients who are bleeding or are in need of an urgent invasive procedure. Use of a systematic approach to assessing and treating these patients based on available evidence and expert opinion can help avoid delays that could adversely affect patient outcomes.

Comparison of different warfarin reversal protocols on surgical delay and complication rate in hip fracture patients

PURPOSE. To compare the effects of different warfarin reversal protocols on surgical delay and complication rate in hip fracture patients. METHODS. Records of 7 men and 17 women aged 68 to 93 (mean, 82) years who were on warfarin and underwent surgery for femoral neck fractures were reviewed. The time to surgery, complication rate, and mortality were recorded, as were the International Normalised Ratio (INR) on admission and the day of operation, as well as the dose, route, and time of administration of vitamin K for reversing the anticoagulation effect of warfarin. Patients were divided into 4 groups based on the warfarin reversal treatment. Group 1 (n=4) included patients who did not receive reversal treatment, as their admission INR was 1.5 or less. Group 2 (n=6) included patients who did not receive reversal treatment even though their INR was >1.6. Group 3 (n=5) included patients who received inappropriate reversal treatment (late or low-dose oral administration). Group 4 (n=9) included patients who received appropriate reversal treatment in terms of dose, route, and time of administration. RESULTS. Among the 4 groups, the mean INR was 2.2 (range, 1.3-4.6) on admission and 1.4 (range, 1.0-1.6) on the day of surgery. Group 1 was excluded from further analysis. Respectively in groups 2, 3, and 4, the mean times to surgery were 2.3, 2.6, and 1.2 days, and the complication rates were 67%, 20%, and 11%. CONCLUSION. Early administration of intravenous vitamin K for hip fracture patients on warfarin is recommended to ensure early operative management and avoid postoperative complications.

An update of consensus guidelines for warfarin reversal

• Despite the associated bleeding risk, warfarin is the most commonly prescribed anticoagulant in Australia and New Zealand. Warfarin use will likely continue for anticoagulation indications for which novel agents have not been evaluated and among patients who are already stabilised on it or have severe renal impairment. • Strategies to manage over-warfarinisation and warfarin during invasive procedures can reduce the risk of haemorrhage. • For most warfarin indications, the target international normalised ratio (INR) is 2.0-3.0 (venous thromboembolism and single mechanical heart valve excluding mitral). For mechanical mitral valve or combined mitral and aortic valves, the target INR is 2.5-3.5. • Risk factors for bleeding with warfarin use include increasing age, history of bleeding and specific comorbidities. • For patients with elevated INR (4.5-10.0), no bleeding and no high risk of bleeding, withholding warfarin with careful subsequent monitoring seems safe. • Vitamin K1 can be given to reverse the anticoagulant effect of warfarin. When oral vitamin K1 is used for this purpose, the injectable formulation, which can be given orally or intravenously, is preferred. • For immediate reversal, prothrombin complex concentrates (PCC) are preferred over fresh frozen plasma (FFP). Prothrombinex-VF is the only PCC routinely used for warfarin reversal in Australia and New Zealand. It contains factors II, IX, X and low levels of factor VII. FFP is not routinely needed in combination with Prothrombinex-VF. FFP can be used when Prothrombinex-VF is unavailable. Vitamin K1 is essential for sustaining the reversal achieved by PCC or FFP. • Surgery can be conducted with minimal increased risk of bleeding if INR ≤ 1.5. For minor procedures where bleeding risk is low, warfarin may not need to be interrupted. If necessary, warfarin can be withheld for 5 days before surgery, or intravenous vitamin K₁ can be given the night before surgery. Prothrombinex-VF use for warfarin reversal should be restricted to emergency settings. Perioperative management of anticoagulant therapy requires an evaluation of the risk of thrombosis if warfarin is temporarily stopped, relative to the risk of bleeding if it is continued or modified.

Perioperative complications in patients on low-molecular-weight heparin bridging therapy

BACKGROUND

Patients taking warfarin are often given interim anticoagulation in the perioperative period. Institutional guidelines that use low-molecular-weight heparin (LMWH) 'bridging' while the international normalized ratio (INR) is sub-therapeutic are often based on the American College of Chest Physicians Anticoagulation Guidelines.

PURPOSE

This study aims to identify if patients at a tertiary referral hospital were anticoagulated in line with these guidelines, and the incidence and nature of bleeding and thromboembolic complications.

METHODS

A retrospective review of the Alfred Hospital General Surgical and 'Hospital at Home' databases was conducted, identifying patients who underwent elective general surgical procedures and received bridging anticoagulation with enoxaparin. Demographics, indication for anticoagulation, bleeding and thromboembolism rates were recorded. Thromboembolic risk was estimated.

RESULTS

The study identified 108 patients. Three-quarters of all patients were anticoagulated with LMWH doses in accordance with the guidelines. Thirty of the 108 patients suffered bleeding complications. This group was younger, weighed less, received higher doses of enoxaparin and were at higher predicted risk of thromboembolism than non-bleeding patients. Wound haematoma, rectal bleeding and intra-abdominal bleeding were the most frequent complications. The peak time of bleeding was 3.5 days after surgery. Twelve patients returned to theatre, 13 were readmitted and 3 received blood transfusion. One patient suffered pulmonary emboli on the first post-operative day.

CONCLUSION

LMWH bridging therapy when prescribed appropriately is associated with low rates of inpatient thromboembolism in elective general surgical patients within our institution, but an unexpectedly high rate of bleeding complications.

Blood component support in acquired coagulopathic conditions: is there a method to the madness?

Acquired coagulopathies are often detected by laboratory investigation in clinical practice. There is a poor correlation between mild to moderate abnormalities of laboratory test and bleeding tendency. Patients who are bleeding due to coagulopathy are often managed with various blood components including plasma, platelets, and cryoprecipitate. However, prophylactic transfusion of these products in a nonbleeding patient to correct mild to moderate abnormality of a coagulation test especially preprocedure is not evidence-based. This article reviews the management of bleeding due to oral anticoagulants and antiplatelet agents, disseminated intravascular coagulation, chronic liver disease, and trauma.

Reversal of antithrombotic agents

Anticoagulants are the mainstay of therapy for thromboembolic diseases. In addition to the more traditional agents, new oral anticoagulants, including dabigatran etexilate, rivaroxaban, and apixaban, have been shown to be effective across several indications. Bleeding is a serious complication associated with any anticoagulant, but many of the traditional parenteral and new oral agents do not currently have specific antidotes. This review describes available and future options for the reversal of the effects of anticoagulants, in particular the new oral agents and discusses current management strategies for bleeding events in clinical practice.

Study of Octaplex dosing accuracy: an in vitro analysis

Prothrombin complex concentrates (PCC) are recommended for urgent warfarin reversal. However, disagreement exists regarding the proper dosing strategy (i.e. fixed vs. weight-based). We measured the in vitro effect of PCC dosing on international normalised ratio (INR) and factor activity. Plasma from warfarin-anticoagulated patients with stable INRs was collected. PCC doses of 1,000, 2,000 and 3,000 IU were added to the samples, and INR and factor activity were analysed before and after PCC. Twenty-three of thirty subjects enrolled had complete data for analysis. INRs were below 1.5 in all samples post-1,000 IU, and decreased further with subsequent doses (p<0.001). Factors II, VII, and X increased with consecutive doses (p<0.01). Linear correlation was seen between INR and factors II, VII and X. Factor IX did not increase consistently nor show correlation with INR reversal. Weight-based dosing was then estimated; INRs were all <1.2 (0.9-1.2) and activity >0.50 IU for factors II, VII and X (0.96-1.52, 0.51-1.45 and 0.81-1.38, respectively). Factor IX did not uniformly correct above 0.50 IU (0.31-1.31). We confirm in vitro that 1,000 IU of Octaplex(®) is able to correct INR to <1.5 but factors were not uniformly >0.50 IU until 2,000 IU, and not >1.00 IU until 3,000 IU. This suggests that INR correction alone may not accurately reflect factor activity, and lends support for weight-based dosing.