Warfarin anticoagulation in the perioperative period: is it safe?

Evaluation of the Safety of Uninterrupted Warfarin Anticoagulation With Tranexamic Acid in Total Joint Arthroplasty

BACKGROUND

The continuation of long-term warfarin therapy is gaining acceptance in minor surgeries but maintaining therapeutic international normalized ratio (INR) values among patients during major orthopedic procedures raises concern. While bridging therapy with low-molecular-weight heparin is currently recommended for patients receiving anticoagulation, few studies have evaluated the safety of continuing warfarin during total joint arthroplasty. This study evaluated the safety and efficacy of continuous warfarin anticoagulation through total joint arthroplasty with and without prophylactic tranexamic acid (TXA).

MATERIALS AND METHODS

We conducted a retrospective, matched-pair analysis of two experimental groups of patients who underwent primary total hip arthroplasty or total knee arthroplasty performed by a single surgeon. Our first experimental group, warfarin plus TXA (warfarin+TXA), consisted of 21 patients who underwent arthroplasty while receiving therapeutic anticoagulation with warfarin (INR, 2.0-3.0) and who received prophylactic TXA. Our second experimental group, warfarin without TXA (warfarin-TXA), consisted of 40 patients who underwent arthroplasty while receiving therapeutic anticoagulation with warfarin (INR, 2.0-3.0) without prophylactic TXA.

RESULTS

The percent change in hemoglobin value after surgery, red blood cells transfused, surgical site infections, bleeding complications, and thrombotic complications were similar between both experimental and control groups. When comparing the historical group with the warfarin+TXA group, the addition of TXA resulted in a statistical decrease in mean red blood cells transfused and estimated blood loss, with no statistically significant increase in complications.

CONCLUSION

Many factors must be considered when choosing perioperative thromboembolic prophylaxis for arthroplasty candidates with medical comorbidities requiring long-term anticoagulation. This study presents data indicating that it could be safe and effective to continue therapeutic warfarin while using prophylactic TXA. [Orthopedics. 2024;47(4):211-216.].

Periprocedural Anticoagulation Management of Patients receiving Warfarin in Qatar: A Prospective Cohort Study

BACKGROUND

The use of anticoagulant bridging remains controversial. This study was conducted to evaluate our warfarin periprocedural management in Qatar and investigate the associated clinical outcomes with such management.

METHODS

A prospective cohort study was designed to describe the periprocedural clinical practice in warfarin patients in Qatar and to compare clinical safety and efficacy outcomes between anticoagulant bridging and nonbridging.

RESULTS

103 patients were recruited. Bridging occurred in 82% of the participants. No thromboembolic events were observed, while 39.1% of patients experienced bleeding events during the study period. The incidence of overall bleeding and major bleeding were numerically higher for bridging group compared to nonbridging but did not reach statistical significance ([30.6% vs 22.2%, P = 0.478] and [12.9% vs 5.6%, P = 0.375], respectively).

CONCLUSION

Warfarin interruption and bridging are overwhelmingly used in warfarin-treated patients in Qatar. While bridging was numerically associated with increased bleeding events, there is no statistical difference in reported clinical events between bridging and nonbridging strategies.

Periprocedural management of patients receiving a vitamin K antagonist or a direct oral anticoagulant requiring an elective procedure or surgery

The periprocedural management of patients receiving chronic therapy with oral anticoagulants (OACs), including vitamin K antagonists (VKAs) such as warfarin and direct OACs (DOACs), is a common clinical problem. The optimal perioperative management of patients receiving chronic OAC therapy is anchored on four key principles: (i) risk stratification of patient-related and procedure-related risks of thrombosis and bleeding; (ii) the clinical consequences of a thrombotic or bleeding event; (iii) discontinuation and reinitiation of OAC therapy on the basis of the pharmacokinetic properties of each agent; and (iv) whether aggressive management such as the use of periprocedural heparin bridging has advantages for the prevention of postoperative thromboembolism at the cost of a possible increase in bleeding risk. Recent data from randomized trials in patients receiving VKAs undergoing pacemaker/defibrillator implantation or using heparin bridging therapy for elective procedures or surgeries can now inform best practice. There are also emerging data on periprocedural outcomes in the DOAC trials for patients with non-valvular atrial fibrillation. This review summarizes the evidence for the periprocedural management of patients receiving chronic OAC therapy, focusing on recent randomized trials and large outcome studies, to address three key clinical scenarios: (i) can OAC therapy be safely continued for minor procedures or surgeries; (ii) if therapy with VKAs (especially warfarin) needs to be temporarily interrupted for an elective procedure/surgery, is heparin bridging necessary; and (iii) what is the optimal periprocedural management of the DOACs? In answering these questions, we aim to provide updated clinical guidance for the periprocedural management of patients receiving VKA or DOAC therapy, including the use of heparin bridging.

Special care dentistry for general dental practice

Although special care dentistry (SCD) is a fairly recent specialty, the principles and practice of SCD have been developed since the 1980s. Shared care of these patients with general dental practitioners remains vital to ensure that comprehensive care is provided. This article aims to discuss some of the patient groups commonly seen in SCD clinics and give an insight into the varied complex medical and social aspects of care which are managed as part of providing appropriate, safe and holistic care.

CLINICAL RELEVANCE

Many patients who currently fall under the remit of special care dentistry could be treated safely in general dental practice. This article acts as an introduction to special care dentistry for general dental practitioners.

How I treat anticoagulated patients undergoing an elective procedure or surgery

The periprocedural management of patients receiving long-term oral anticoagulant therapy remains a common but difficult clinical problem, with a lack of high-quality evidence to inform best practices. It is a patient's thromboembolic risk that drives the need for an aggressive periprocedural strategy, including the use of heparin bridging therapy, to minimize time off anticoagulant therapy, while the procedural bleed risk determines how and when postprocedural anticoagulant therapy should be resumed. Warfarin should be continued in patients undergoing selected minor procedures, whereas in major procedures that necessitate warfarin interruption, heparin bridging therapy should be considered in patients at high thromboembolic risk and in a minority of patients at moderate risk. Periprocedural data with the novel oral anticoagulants, such as dabigatran, rivaroxaban, and apixaban, are emerging, but their relatively short half-life, rapid onset of action, and predictable pharmacokinetics should simplify periprocedural use. This review aims to provide a practical, clinician-focused approach to periprocedural anticoagulant management.

[Bridging, interruption and switching of anticoagulants in trauma surgery]

Patients under long-term administration of vitamin K antagonists may require temporary interruption of anticoagulation therapy for invasive procedures or trauma surgery. Due to the long half-life of these substances bridging therapy with anticoagulants having a shorter half-life may become necessary. In this situation the risk of bleeding due to the intervention and the risk of thromboembolism due the underlying disease must be assessed. Low molecular weight heparins (LMWHs) are considered to be the medication of choice for bridging anticoagulation, mainly due to practical reasons and as they do not require coagulation monitoring and dose adjustment out of hospital treatment is feasible. Low molecular weight heparins are not authorized for the indication of bridging anticoagulation, however, on the basis of recent studies on large patient cohorts, the evidence of efficacy and safety is significantly better for LMWHs than for unfractionated heparin. New oral anticoagulants will soon become available for stroke prevention in patients with atrial fibrillation and for treatment of venous thromboembolism. Due to the shorter half-lives these compounds will no longer require bridging anticoagulation. However, the trauma surgeon should be familiar with the dosing regimens for different indications in order to adequately decide about the preoperative cessation and the perioperative pause of these anticoagulants.

[Bridging anticoagulation]

Patients on anticoagulants of the vitamin K antagonist type may sometimes be scheduled for invasive procedures or surgical operations. In order to minimize the risk of thromboembolism caused by the interruption of chronic anticoagulation for the procedure, temporary administration of anticoagulants with shorter half-lives is required (so-called bridging anticoagulation). The present review outlines the spectrum of risks during this period regarding both thromboembolism and major bleeding. Low molecular weight heparins may be considered the medication of choice for bridging anticoagulation, mainly for practical reasons. Since they require no coagulation monitoring or dose adjustment, outpatient treatment is feasible. Such heparins are not labelled for the indication of bridging anticoagulation. However, based on recent studies of large patient cohorts, evidence of their efficacy and safety is significantly more solid than for unfractionated heparin. A simple dosing scheme for low molecular weight heparins is given here and all requirements are discussed for safe guidance through episodes of bridging anticoagulation.

Oral anticoagulation in surgical procedures: risks and recommendations

Surgery in anticoagulated patients is problematic. Coumarin therapy is often discontinued or reversed to reduce the perioperative bleeding risk. Meanwhile, the thromboembolic risk is enhanced. We sought to determine the frequency of bleeding and thromboembolism in anticoagulated patients undergoing routine surgery and to investigate the role of patient characteristics and the level of anticoagulation. We studied patients who attended the Leiden Anticoagulation Clinic for treatment relating to mechanical heart valve prostheses, atrial fibrillation or myocardial infarction and underwent surgery at the Leiden University Medical Centre between 1994 and 1998. Outcome events were bleeding and thromboembolism in the perioperative period. Seventy-two complications occurred in 603 interventions, yielding an overall frequency of 11.9% [95% confidence interval (CI): 9.3-14.9], 9.5% (n = 57) for haemorrhage and 2.5% (n = 15) for thromboembolism. Younger patients tended to have more complications [odds ratio (OR) for >65 years of age: 0.5, 95% CI 0.3-1.0] as did patients with atrial fibrillation (OR for atrial fibrillation versus mechanical heart valve prostheses: 1.8, 95% CI 0.8-4.2). High postoperative levels of anticoagulation were associated with a slightly increased risk of complications [OR international normalized ratio (INR) > 3 vs. INR < 2: 1.3, 95% CI 0.6-3.0]. We conclude that routine surgery in anticoagulated patients yields a high perioperative bleeding and thromboembolic risk. While neither patient characteristics nor the level of anticoagulation appeared to play a major role in the occurrence of complications, the risk was clearly associated to the type of surgery, with the highest risk in thoracic surgery.

Estimation of acute blood loss in the anticoagulated rabbit model using 3 modalities of radio frequency energy ablation

PURPOSE

An anticoagulated animal model was tested to evaluate estimated acute blood loss (EABL) following tissue ablation with 3 modalities of radio frequency (RF) thermal energy.

MATERIALS AND METHODS

Four groups of randomly divided rabbits were established. Group 1 (3 control and 3 anticoagulated rabbits) underwent sham treatment (noRF), group 2 (2 control and 7 anticoagulated) received single probe dry RF (dRF) (475 KHz and 5 W for 2 minutes), group 3 (2 control and 7 anticoagulated) received single probe wet RF (wRF) (475 KHz with 14.6% hypertonic saline at 50 W for 40 seconds) and group 4 (3 control and 7 anticoagulated) was treated with vapor RF (vRF) (0.9% normal saline for 10 seconds). Oral warfarin sodium was the anticoagulant. Following a midline incision ablation was performed on the left kidney and liver. Pre-weighed gauze pads were used to collect EABL for a 5-minute observation period after needle probe removal. Temperature data were recorded from the right kidney using fiberoptic thermocouples. Lesions were grossly inspected and measured.

RESULTS

Anticoagulation resulted in super anticoagulated animals with an average prothrombin time of almost 140 seconds. EABL was the least from the ablated left kidney for vRF (50 mg), followed by wRF (260 mg), dRF (390 mg) and noRF (1,800 mg). EABL was the least from the liver for vRF (10 mg), followed by wRF (470 mg), dRF (1,260 mg) and noRF (2,680 mg). A greater percent of total ablative time at 10 mm was spent at greater than 50C during wRF and vRF. Measured ablative lesions size was largest following vRF ablation.

CONCLUSIONS

The thermal coagulative effects of RF ablation resulted in less bleeding compared with controls in this orally anticoagulated animal model. The novel RF modality vRF is introduced.

Preoperative monitoring of warfarin in cutaneous surgery

BACKGROUND

We report a patient who developed postoperative bleeding as a result of inadvertent excessive warfarin intake. We subsequently introduced a policy of checking the international normalization ratio (INR) 24 h before cutaneous surgery for all patients on warfarin.

OBJECTIVES

To review the perioperative INR and outcome of all patients on warfarin who had cutaneous surgery from January 1999 to June 2002 at the Department of Dermatology, Sunderland Royal Hospital.

METHODS

A retrospective review was undertaken from patients' medical records.

RESULTS

Sixty-eight patients (1.84% of total) underwent 85 skin procedures comprising 33 excisions, 16 punch biopsies, 15 curettages, 13 diagnostic biopsies, five shave biopsies, two Mohs micrographic surgical excisions and one delayed reconstruction. Repairs included 50 direct closures, five secondary intention healing, seven local flaps, two full-thickness skin grafts and 20 by electrocautery. Forty-five surgical procedures were undertaken with the INR checked on the day of surgery, 37 procedures within 24 h, and three within 2 days. The preoperative INR ranged from 1.1 to 3.4, median 2.5. There was no excess intraoperative or postoperative bleeding or haematoma for all patients.

CONCLUSIONS

Our experience supports the continued and safe use of warfarin for a wide variety of cutaneous surgical procedures with a preoperative INR of < 3.5. We recommend a routine INR before the procedure, preferably within 24 h.

The frequency and effects of cytochrome P450 (CYP) 2C9 polymorphisms in patients receiving warfarin

BACKGROUND

Warfarin sodium (warfarin) is commonly prescribed in surgical practice. Warfarin use is complicated by an unpredictable dose response that may be due in part to genetically determined differences in metabolic capacity. To better understand the interaction between genotype and response to warfarin therapy, we determined the frequency and functional effects of polymorphisms of the predominant cytochrome P450 subfamily responsible for warfarin metabolism (eg, CYP2C9) in an ethnically defined U.S. patient population.

DESIGN

Patients requiring chronic anticoagulation with warfarin sodium (warfarin) were recruited over an 11-month period (June 1999 through May 2000) from the inpatient and outpatient divisions of a tertiary care medical center in this prospective observational study. Clinical and demographic information was collected and CYP2C9 genotype was determined.

RESULTS

One hundred fifty-three patients receiving warfarin therapy for at least four weeks and comprising two ethnic groups [33 African Americans (22%) and 120 Caucasians (78%)] were genotyped. The mean weekly warfarin dose (+/-SEM) for all patients [36.9 (+/- 1.5) mg] was not influenced by gender [85 males (56%), 68 females (44%)] or ethnicity (p>0.05 for both), but was significantly affected by age (p = 0.006 for weight adjusted warfarin dose). The frequencies of CYP polymorphisms were as follows: 2C9*2 (24/153) 15.7%, 2C9*3 (23/153) 15.0%. There were no gender differences in polymorphism frequency (CYP2C9*2 frequency = (13/ 85) 15.3% in males, (12/68) 17.6% in females, p=0.74; CYP2C9*3 frequency = (15/85) 17.6% in males and (8/68) 11.8% in females, p = 0.38). CYP polymorphisms were much less common in African Americans than Caucasians [(5/33) 15.2% versus (47/120) 39.2%, respectively p = 0.05)]. Patients with CYP polymorphisms (2C9*2, 2C9*3) had significantly lower warfarin doses compared to patients with wild-type genotypes [30.6 (+/- 2.5) mg versus 40.1 (+/- 1.7) mg, p = 0.0021] . Stepwise backward regression analysis suggested a moderate ability to predict warfarin dose based on CYP genotype (r2 = 0.26), p < 0.01).

CONCLUSIONS

CYP2C9 polymorphisms are common, associated with significant reductions in warfarin dose, and partly account for interpatient variability in warfarin sensitivity. As interactions between genetic factors and other variables that influence warfarin effect are more completely understood, CYP analysis may prove a useful adjunct for increasing the safety and efficacy of this agent.

Postoperative stroke after stopping warfarin for cutaneous surgery

BACKGROUND

Two patients undergoing cutaneous surgery had thromboembolic strokes within 1 week after surgery. Both patients had been taking warfarin for prevention of thromboembolism and warfarin was stopped 3-7 days prior to surgery.

OBJECTIVE

To examine the rationale and problems associated with preoperative warfarin discontinuation.

METHODS

Review of the medical literature.

RESULTS

When warfarin is stopped prior to surgery and restarted soon after surgery, the patient is at increased risk for thromboembolism. Although it is commonly believed that continuing warfarin during surgery is associated with an increased bleeding risk, for cutaneous surgery, this risk is extremely low and can be easily managed.

CONCLUSION

Warfarin should not be discontinued prior to cutaneous surgery because of the risk of thromboembolic stroke.

Clinical utilization of the international normalized ratio (INR)

The prothrombin time (PT) is one of the most important laboratory tests to determine the functionality of the blood coagulation system. It is used in patient care to diagnose diseases of coagulation, assess the risk of bleeding in patients undergoing operative procedures, monitor patients being treated with oral anticoagulant (coumadin) therapy, and evaluate liver function. The PT is performed by measuring the clotting time of platelet-poor plasma after the addition of calcium and thromboplastin, a combination of tissue factor and phospholipid. Intra- and interlaboratory variation in the PT was a significant problem for clinical laboratories in the past, when crude extracts of rabbit brain or human placenta were the only source of thromboplastin. The international normalized ratio (INR), developed by the World Health Organization in the early 1980s, is designed to eliminate problems in oral anticoagulant therapy caused by variability in the sensitivity of different commercial sources and different lots of thromboplastin to blood coagulation factor VII. The INR is used worldwide by most laboratories performing oral anticoagulation monitoring, and is routinely incorporated into dosage planning for patients receiving warfarin. Although the recent availability of sensitive PT reagents prepared from recombinant human tissue factor (rHTF) and synthetic phospholipids eliminated many of the earlier problems associated with the use of crude thromboplastin preparations, local instrument variability in the INR still remains a problem. Presently, the use of plasma calibrants seems the best solution to this problem. Standardizing the point-of-care instruments for INR monitoring is another dilemma faced by the industry. Ultimately, new generations of anticoagulant drugs may eliminate the need for laboratory monitoring of anticoagulant therapy.