Perioperative Management Of Anticoagulation Research Articles

Update on Perioperative Antithrombotic Management

Abstract Purpose of the Review In this review, we discuss the recent studies and recommendations on the perioperative management of oral anticoagulant and antiplatelet drugs. Recent Findings In elective surgery, clear and simple recommendations exist for oral anticoagulants and antiplatelet drugs. The shorter stopping intervals with direct-acting oral anticoagulants have simplified the perioperative management compared with vitamin K antagonists. The specific use of laboratory testing is suggested for bleeding patients treated with antithrombotic drugs or for emergent surgery. The postoperative prevention of thromboembolism has gained more attention, and individualized strategies including extended treatment or use of aspirin has been suggested in specific patients. The use of risk scores might be helpful for decision making. Summary The perioperative management of anticoagulants and antiplatelet drugs is still challenging, especially in urgent or emergent surgery. The use of individualized strategies to prevent perioperative bleeding and thromboembolic events rather than a “one-size-fits-all” approach is suggested.

Perioperative Management of Traditional and Direct Oral Anticoagulants in Hip Fracture Patients

Hip fractures are an increasingly common injury in the senior population and almost always require surgical fixation or prosthetic replacement. These surgeries, according to the American Academy of Orthopaedic Surgeons, are considered high-risk for bleeding, especially in a population fraught with comorbidities and often presenting on anticoagulation medications. Direct oral anticoagulants represent a class of drugs that have been becoming more popular in use in this population, with many benefits over the historically used Warfarin. There are recommendations for preoperative discontinuation and postoperative resumption of these medications, which can be more readily managed for elective surgeries. However, there is a paucity of literature detailing best practice guidelines for the perioperative management of direct oral anticoagulants when a patient presents with a hip fracture. This review article summary of the periprocedural management of DOACs for hip surgery was developed by examining the American College of Chest Physicians evidence-based clinical practice guidelines, Perioperative Guidelines on Antiplatelet and Anticoagulant Agents written by anesthesiologists, various retrospective studies, and drug labels for pharmacokinetic data. These recommendations should be used as a guideline, along with the collaboration of multidisciplinary hospital teams during inpatient admission, to manage these complex patients.

Hematoma Prevention Using Tachosil (Fibrin Sealant) Patch during Insertion of Cardiovascular Implantable Electronic Devices without Suspending Antithrombotics: Three Case Reports

Patients undergoing insertion of cardiac implantable electronic devices often exhibit perioperative hemorrhagic complications. Perioperative antithrombotic management, which balances the risk of acute thrombosis and postoperative bleeding, is therefore important for these patients. In this case report, we present three cases of cardiovascular implantable electronic device (CIED) insertion. While the three patients each had different reasons for not discontinuing antithrombotic medications, they all needed CIEDs. During the CIED implantation procedures, a small incision was made on the pectoralis muscle region to obtain a small subcutaneous pocket, and Tachosil, a fibrin sealant patch, was inserted below and above the inserted device. The patients showed no pocket hematoma formation or any hemorrhagic complications. We thus concluded the application of a fibrin sealant patch could be an option for perioperative anticoagulation management without interruption of anticoagulants and antiplatelets.

Anticoagulation Stewardship to Bridge the Implementation Gap in Perioperative Anticoagulation Management.

Lack of alignment of care protocols among providers in health care is a driver of increased costs and suboptimal patient outcomes. Perioperative anticoagulation management is a good example of a complex area where protocol creation is a clinical challenge that demands input from multiple experts. Questions regarding the need for anticoagulation interruptions are frequent. Yet, due to layers of complexity involving analysis of anticoagulation indication, surgical risk, and anesthesia-associated bleeding risk as well as institutional practices, there is heterogeneity in how these interruptions are approached. The recent perioperative anticoagulation guidelines from the American College of Chest Physicians summarize extensive evidence for the management of anticoagulant and antiplatelet medications in patients who undergo elective interventions. However, implementation of these guidelines by individual clinicians is highly varied and often does not follow the best available clinical evidence. Against this background, anticoagulation stewardship units, which exist to improve safety and quality monitoring for the anticoagulated patient, are of growing interest. These units provide a bridge for the implementation of value-based, high-quality guidelines for patients who need perioperative anticoagulation interruption. We use a case to pragmatically illustrate the problem and tactics for change management and implementation science that may facilitate the adoption of perioperative anticoagulation guidelines.

Anticoagulation management in elderly patients with proximal femur fractures- overview of current concepts.

Proximal femur fractures (PFF) are common injuries in elderly patients and can have considerable effects on their quality of life, morbidity, and mortality. Due to pre-existing comorbidities, the prevalence of anticoagulated patients is increasing. The right timing for surgery and perioperative anticoagulation treatment remains controversial. This overview aims to summarize current practices in the pre- and postoperative anticoagulation management and the recommended time to surgery in elderly patients with PFF. Time to surgery for anticoagulated patients is often prolonged due to worries about serious perioperative bleeding and higher transfusion demands. But the delay of surgical PFF treatment increases the risk for perioperative complications like pulmonary embolism, pneumonia, deep vein thrombosis and urinary tract infections. Early surgery can be achieved with a consistent and interdisciplinary perioperative anticoagulation management. Antiplatelets do not have to be discontinued and surgery should be performed early without delay. For patients taking vitamin K antagonists (VKA) an INR less than 1.5 is recommended prior to surgery, which can be achieved by pausing VKA intake or by administering vitamin K, prothrombin complex concentrate (PCC) or fresh frozen plasma (FFP). For the treatment with direct oral anticoagulants (DOAC) a plasma drug level of under 50 pg/mL is considered safe for surgery. If the plasma level can not be determined, a gap of 24 h between the last DOAC dose and surgery is recommended. The systemic administration of tranexamic acid can reduce overall blood loss and transfusion rates in anticoagulated patients with PFF. Surgical treatment of PFF should be performed within 24 h, as delayed surgery increases the risk for perioperative complications. This also applies to anticoagulated patients, when clinically appropriate. International and interdisciplinary guidelines are necessary to ensure early and appropriate treatment of anticoagulated elderly patients with PFF.

Perioperative Management of Anticoagulation and Antithrombotic Therapy

The latest updates to the NCCN Guidelines for perioperative management of anticoagulation and antithrombotic therapies reflect significant changes in the use of bridging anticoagulation. For patients with low- to intermediate-risk atrial fibrillation, the standard of care has shifted toward reduced reliance on bridging anticoagulation. The rationale for this shift is based on the BRIDGE trial, which revealed a 3-fold greater risk of major bleeding without significant reduction in thrombotic outcomes in patients receiving bridging therapy. In patients with mechanical heart valves, findings from the PERIOP2 study led to similar conclusions. Both of these studies have contributed to a paradigm shift in perioperative anticoagulation management, pivoting toward personalized therapy based on patient-specific bleeding and thrombotic risks. For emergent or elective surgeries, the NCCN Guidelines provide a framework for more individualized decision-making, emphasizing the need for ongoing cooperation among physicians, surgeons, and patients.

Peri-Procedural Management of Direct-Acting Oral Anticoagulants (DOACs) in Transcatheter Miniaturized Leadless Pacemaker Implantation.

Data on peri-operative management of direct-acting oral anticoagulants (DOACs) during transcatheter pacing leadless system (TPS) implantations remain limited. This study aimed to evaluate a standardized DOAC management regime consisting of interruption of a single dose prior to implantation and reinitiation within 6-24 h; also, patient clinical characteristics associated with this approach were identified. Consecutive patients undergoing standard TPS implantation procedures from two Swiss tertiary centers were included. DOAC peri-operative management included the standardized approach (Group 1A) or other approaches (Group 1B). Three hundred and ninety-two pts (mean age 81.4 ± 7.3 years, 66.3% male, left ventricular ejection fraction 55.5 ± 9.6%) underwent TPS implantation. Two hundred and eighty-two pts (71.9%) were under anticoagulation therapy; 192 pts were treated with DOAC; 90 pts were under vitamin-K antagonist. Patients treated with DOAC less often had structural heart disease, diabetes mellitus, and advanced renal failure. The rate of major peri-procedural complications did not differ between groups 1A (n = 115) and 1B (n = 77) (2.6% and 3.8%, p = 0.685). Compared to 1B, 1A patients were implanted with TPS for slow ventricular rate atrial fibrillation (AF) (p = 0.002), in a better overall clinical status, and implanted electively (<0.001). Standardized peri-procedural DOAC management was more often implemented for elective TPS procedures and did not seem to increase bleeding or thromboembolic adverse events.

Influence of perioperative antiplatelet and anticoagulant medication management on bleeding events in dermatosurgery-A prospective observational study.

Perioperative management of antiplatelet and anticoagulant (AP/AC) therapy is a matter of balancing the risks of bleeding and thromboembolic events. Reliable data for dermatosurgery are still lacking, especially for direct oral anticoagulants (DOAC). The aim was to prospectively evaluate the influence of AP/AC-medication on bleeding risk in dermatosurgery with focus on exact intervals between DOAC intake and procedure performed on post-operative bleeding. Patients with or without AP/AC-therapy were included in the study without randomization. Exact times of DOAC-intake, procedure performed and post-operative bleeding were documented. Data collection was prospectively and standardized done by one person. We evaluated 1852 procedures in 675 patients. Post-operative bleeding occurred after 15.93% (n = 295) of all procedures, but only a few of them were severe (1.57%, n = 29). Compared to patients without AP/AC-medication, severe post-operative bleeding occurred significantly more often under dual antiplatelet therapy (11.76%, n = 2; p = 0.0166) and bridging of either vitamin K antagonist (9.09%, n = 2; p = 0.0270) or DOAC (15.38%, n = 2; p = 0.0099). There was no significant difference in the frequency of severe bleeding regarding to the preoperative DOAC-free period. Although AP/AC-therapy is associated with a significant higher rate of post-operative bleeding, no life-threatening bleeding was recorded. Long preoperative pausing or bridging of DOAC does not lead to significantly less severe bleeding events.

Potential for a Virtual Care Model in the Perioperative Management of Anticoagulant Therapy: A 5-Year Retrospective Clinic Review

Abstract Background With a trend toward greater virtual care in selected clinical settings, perioperative anticoagulant management appears well suited for this care delivery model. We explored the potential for virtual care among patients who are receiving anticoagulant therapy and require perioperative management around the time of an elective surgery/procedure. Methods We undertook a retrospective review of patients who were receiving anticoagulant therapy, either a direct oral anticoagulant (DOAC) or warfarin, assessed in a perioperative anticoagulation-bridging clinic over a 5-year period from 2016 to 2020. Using prespecified criteria, we determined the proportion of patients who likely would be suitable for virtual care (receiving a DOAC or warfarin and having a minimal- or low-/moderate-bleed-risk surgery/procedure), those who likely would be suitable for in-person care (receiving warfarin and requiring heparin bridging for a mechanical heart valve), and patients who would be suitable for either care delivery model (receiving a DOAC or warfarin, but not with a mechanical heart valve, and requiring a high-bleed-risk surgery/procedure). Results During the 5-year study period, there were 4,609 patients assessed for perioperative anticoagulant management in whom the most widely used anticoagulants were warfarin (37%), apixaban (30%), and rivaroxaban (24%). Within each year assessed, 4 to 20% of all patients were undergoing a minimal-bleed-risk procedure, 76 to 82% were undergoing a low-/moderate-bleed-risk surgery/procedure, and 10 to 39% were undergoing a high-bleed-risk surgery/procedure. The proportion of patients considered suitable for virtual, in-person, or either virtual or in-person management was 79.6, 7.1, and 13.3%, respectively. Conclusion In patients who were assessed in a perioperative anticoagulation clinic, there was a high proportion of patients in whom a virtual care model might be suitable.

Compliance to perioperative anticoagulation protocols in elderly patients undergoing elective orthopedic procedures: a retrospective observational cohort study on 548 patients

BackgroundCompliance with perioperative anticoagulation guidelines is essential to minimize bleeding and thromboembolic risks in patients undergoing surgery. Compared to vitamin-K antagonists (VKAs), perioperative management of direct oral anticoagulants (DOACs) contains fewer steps. Therefore, we hypothesized that noncompliance with guidelines in VKA users is higher than in DOAC users. The primary aim of our study was to investigate the difference in noncompliance to perioperative anticoagulant management guidelines between elderly patients using VKAs versus those using DOACs. The secondary aim was to determine the difference in occurrence of conflicting information communicated to the patients and the difference in incidence of coagulation-related adverse events.MethodsThis retrospective non-controlled observational cohort study examined elderly patients undergoing elective orthopedic surgery in a teaching hospital in the Netherlands. All patients undergoing elective orthopedic surgery between 1 May 2016 and 1 January 2020, aged 70 years and over, using VKAs or DOACs were selected. Nonelective surgeries were excluded. The primary outcome was the noncompliance to perioperative anticoagulant management guidelines. Secondary outcomes were missing or conflicting information on anticoagulation management communicated to the patient and coagulation-related adverse events. For continuous data, the unpaired T-test was used and for categorical data, the chi-square test.ResultsIn patients using VKAs, noncompliance to one of the steps of perioperative anticoagulation management was 81%, compared to 55% in patients using DOACs (p < 0.001). In most cases, VKAs or DOACs were interrupted for longer than recommended. In 13% of patients using a VKA with perioperative bridging, bridging was not conducted as recommended in the guidelines. In 13% of patients using a DOAC, a low-molecular-weight heparin (LMWH) was prescribed while a DOAC had already been restarted postoperatively. VKA users received conflicting information about perioperative anticoagulation management more often than DOAC users (33% versus 20%; p < 0.001). No difference was seen in postoperative coagulation-related complications.ConclusionGuidelines compliance in DOAC users is higher than in VKA users. Clinical decision support to help in selecting the right interruption interval in DOAC users, simplified standardized perioperative management, good coordination of instructions given to patients, and familiarity with updated guidelines are important in reducing noncompliance.

Perioperative Anticoagulation in Patients with Cancer.

There is a paucity of evidence for managing perioperative anticoagulation in patients with cancer. This review aims to provide clinicians who provide care for patients with cancer an overview of the available information and strategies needed to provide optimal care in a perioperative setting. There is new evidence available around the management of perioperative anticoagulation in patients with cancer. The new literature and guidance were analyzed and summarized in this review. Management of perioperative anticoagulation in individuals with cancer is a challenging clinical dilemma. The approach to managing anticoagulation requires clinicians to review both disease and treatment specific patient factors that can contribute to both thrombotic and bleed risks. A thorough patient-specific assessment is essential in ensuring patients with cancer receive appropriate care in the perioperative setting.

Exploration and Practice of Medicine Pathway for Perioperative VTE Prophylactic Anticoagulant Treatment.

Using perioperative VTE prophylactic anticoagulant pathway delicacy management, we aimed to explore the role of clinical pharmacists in perioperative VTE prophylactic anticoagulant treatment and the effect of the clinical medicine pathway implementation. In compliance with evidence-based medicine, combined with clinical practice, clinical pharmacists participated in the formulation of the perioperative anticoagulant clinical medicine pathway. The PDCA cycle was strictly implemented. Urologic Department, Affiliated Hospital of Qingdao University, Qingdao Shandong, China, served as a pilot department for the evaluation of the effect of drug clinical pathway implementation. The anticoagulant clinical medicine pathway for the urologic department was formulated and implemented from October 2020 to August 2021. The entry rate gradually increased, and the accuracy of thrombosis risk assessment improved. The proportion of drugs in the department and the per capita drug cost decreased significantly. The perioperative VTE prophylactic anticoagulant pathway showed significant achievements in the rational use of urologic anticoagulant drugs, lowering the cost of medical care. Therefore, it could be considered a novel long-term mechanism for rational analgesia drug use.

The bridging conundrum: perioperative management of direct oral anticoagulants for venous thromboembolism

Most patients diagnosed with venous thromboembolism (VTE) are currently treated with direct oral anticoagulants (DOACs). Before an invasive procedure or surgery, clinicians face the challenging decision of how to best manage DOACs. Should the DOAC be held, for how long, and are there instances where bridging with other anticoagulants should be considered? Although clinical trials indicate that most patients taking DOACs for atrial fibrillation do not require bridging anticoagulation, the optimal strategy for patients with a history of VTE is undefined. In this review, we present a case-based discussion for DOAC interruption perioperatively in patients receiving anticoagulation for management of VTE.

Proactive Risk Assessment through Failure Mode and Effect Analysis (FMEA) for Perioperative Management Model of Oral Anticoagulant Therapy: A Pilot Project

Correct perioperative management of anticoagulant therapy is essential to prevent thromboembolic events and reduce the risk of bleeding. The lack of universally accepted guidelines makes perioperative anticoagulant therapy management difficult. The present study aims to identify the perioperative risks of oral anticoagulant therapy and to reduce adverse events through Failure Mode and Effect Analysis (FMEA). A multidisciplinary working group was set up, and four main phases of the process were identified. Each of these phases was divided into micro-activities to identify the related possible failure modes and their potential consequences. The Risk Priority Number was calculated for each failure mode. Seventeen failure modes were identified in the entire perioperative period; those with a higher priority of intervention concern the incorrect timing between therapy suspension and surgery, and the incorrect assessment of the bleeding risk related to the invasive procedure. The FMEA method can help identify anticoagulant therapy perioperative failures and implement the management and patient safety of surgical procedures.

Perioperative Management of Vitamin K Antagonists and Direct Oral Anticoagulants: A Systematic Review and Meta-analysis

The management of patients who are receiving chronic oral anticoagulation therapy and require an elective surgery or an invasive procedure is a common clinical scenario. What is the best available evidence to support the development of American College of Chest Physicians guidelines on the perioperative management of patients who are receiving long-term vitamin K agonist (VKA) or direct oral anticoagulant (DOAC) and require elective surgery or procedures? A literature search including multiple databases from database inception through July 16, 2020, was performed. Meta-analyses were conducted when appropriate. In patients receiving VKA (warfarin) undergoing elective noncardiac surgery, shorter (< 5days) VKA interruption is associated with an increased risk of major bleeding. In patients who required VKA interruption, heparin bridging (mostly with low-molecular-weight heparin [LMWH]) was associated with a statistically significant increased risk of major bleed (relative risk [RR], 9.1; 95%CI, 1.62-51.3), representing a very low certainty of evidence (COE). Compared with DOAC interruption 1 to 4days before surgery, continuing DOACs was not associated with a statistically significant difference in the risk of bleeding, representing a very low COE. Continuing dabigatran was associated with a statistically significant increased risk of thromboembolism (RR, 2.2; 95%CI, 1.3-3.8), representing a low COE. In patients who needed DOAC interruption, bridging with LMWH was associated a with statistically significant increased risk of minor bleeding compared with no bridging (RR, 1.7; 95%CI, 1.13-2.7), representing a low COE. The certainty in the evidence supporting the perioperative management of anticoagulants remains limited. No high-quality evidence exists to support the practice of heparin bridging during the interruption of VKA or DOAC therapy for an elective surgery or procedure or for the practice of interrupting VKA therapy for minor procedures, including cardiac device implantation, or continuation of a DOAC vsshort-term interruption of a DOAC (1-4days) in the perioperative period.

Protocols for perioperative management of direct oral anticoagulants in hospitals: opportunities for improvement

Objectives To investigate and describe the protocolized perioperative management in patient using Direct oral anticoagulants (DOACs) in Dutch hospitals. Methods Between August and December 2020, a nationwide survey in 70 hospitals in the Netherlands was conducted. We asked hospital pharmacists to submit their protocols for perioperative management of DOAC (apixaban, dabigatran, edoxaban and rivaroxaban) users. The protocols were assessed for a number of parameters divided into categories: interruption and restart timetables DOACs for elective procedures, criteria for the start of an urgent procedure without antidotes, criteria for the use of antidotes and advised antidotes for urgent procedures. Results A total of 49 hospitals (70%) sent a protocol for perioperative management of DOACs. Two pairs of protocols were identical because hospitals cooperated closely, leaving 47 individual protocols for analysis. Thirty-five of these protocols contained a policy for both elective and urgent procedure; five protocols contained only a policy for elective and seven only for urgent procedures. In protocols for elective procedure, we found great variation in interruption and restart timetables intended for patients with renal impairment (Estimated Glomerular Filtration Ratio < 80 ml/min). In case of urgent procedures, there is variation in choice of antidote, criteria for administration of an antidote and antidote dosing. Conclusion This study provides an overview of the current state of the perioperative protocols in the Netherlands in patients treated with direct oral anticoagulants. Protocols are often not complete and show important and unwanted variation. We have found that national guidelines do not provide unambiguous advice on all points (urgent procedures) and are therefore often elaborated at a local level. The results of this research can help in improving and harmonizing the perioperative protocols on a national level.

Peri-interventional management of platelet aggregation inhibition and anticoagulation in urology

Perioperative management of anticoagulation in patients receiving long-term anticoagulation or platelet aggregation inhibitors requires an individual consideration of competing risks. If the risk for bleeding is low, anticoagulation can often be continued. If it is necessary to pause anticoagulation, the necessity and dosage of bridging must be determined based on the individual risk of thromboembolism. Only patients with ahigh risk of thromboembolism should receive bridging in the full therapeutic dosage. The timing of pausing anticoagulation depends on the risk of bleeding from the urological intervention and the renal function of the patient. Platelet aggregation inhibitors should not be discontinued in the first month after coronary stent implantation, especially after acute coronary syndrome.

The Perioperative Management of Antiplatelet and Anticoagulant Drugs in Hip Fractures: Do the Surgery as Early as Possible.

Hip fractures are among the most common fractures operated by orthopedic surgeons. Many elderly patients, who account for a significant percentage of hip fractures, suffer from medical conditions requiring antiplatelet and anticoagulant administration. Meanwhile, considerable evidence recommends early surgery within 48b hours of admission. We aim to review the existing evidence regarding the perioperative management of antiplatelet and anticoagulant drugs in hip fractures. It was concluded that surgery for hip fractures in patients with antiplatelet drug consumption should not be delayed unless a clear contraindication exists. Active reversal strategies are indicated for patients with hip fractures and warfarin therapy. However, evidence for the safety of these agents in pregnancy, breastfeeding state, and adolescence has not yet been established. Little data exists about perioperative management of direct-acting oral anticoagulants in hip fractures. Early surgery after 12-24 hours of drug cessation has been suggested in studies; however, it should be employed cautiously. Despite extensive research, the importance of the issue necessitates additional higher-quality studies.

Postmastectomy Breast Reconstruction is Safe in Patients on Chronic Anticoagulation.

Background Postmastectomy breast reconstruction (PMR) increases patient satisfaction, quality of life, and psychosocial well-being. There is scarce data regarding the safety of PMR in chronic anticoagulated patients. Perioperative complications can reduce patient satisfaction; therefore, it is important to elucidate the safety of PMR in these patients. Methods A retrospective case–control study of patients who underwent PMR with implants and were on chronic anticoagulation was performed at our institution. Inclusion criteria were women ≥ 18 years old. Exclusion criteria included autologous reconstructions, lumpectomy, and oncoplastic procedures. Two controls for every one patient on anticoagulation were matched by age, body mass index, radiotherapy, smoking history, type of reconstruction, time of reconstruction, and laterality. Results From 2009 to 2020, 37 breasts (20 patients) underwent PMR with implant-based reconstruction and were on chronic anticoagulation. A total of 74 breasts (40 patients) who had similar demographic characteristics to the cases were defined as the control group. Mean age for the case group was 53.6 years (standard deviation [SD] = 16.1), mean body mass index was 28.6 kg/m 2 (SD = 5.1), and 2.7% of breasts had radiotherapy before reconstruction and 5.4% after reconstruction. Nine patients were on long-term warfarin, six on apixaban, three on rivaroxaban, one on low-molecular-weight heparin, and one on dabigatran. The indications for anticoagulation were prior thromboembolic events in 50%. Anticoagulated patients had a higher risk of capsular contracture (10.8% vs. 0%, p = 0.005). There were no differences regarding incidence of hematoma (2.7% vs. 1.4%, p = 0.63), thromboembolism (5% vs. 0%, p = 0.16), reconstructive-related complications, or length of hospitalization (1.6 days [SD = 24.2] vs. 1.4 days [SD = 24.2], p = 0.85). Conclusion Postmastectomy implant-based breast reconstruction can be safely performed in patients on chronic anticoagulation with appropriate perioperative management of anticoagulation. This information can be useful for preoperative counseling on these patients.

Perioperative Anticoagulation Management.

Management of anticoagulation in individuals undergoing operative procedures is a complex situation. Each case should be assessed individually with proper risk assessment, monitoring, and plan for perioperative and postoperative anticoagulation. Clinical evidence for the management of these patients is relatively scarce, and clinicians are often assessing each individual case with minimal guidance. This review provides nurses with a summary of available literature on the assessment, laboratory monitoring, timing of adjusting anticoagulation, and bridging prior to procedures. In addition to general perioperative anticoagulation management, this review discusses perioperative management in special populations and provides a summary on principles when anticoagulation should be resumed following a procedure.