Novel oral anticoagulants for VTE prevention in orthopedic surgery: overview of phase 3 trials

DOACs in the Anticoagulation of Mechanical Valves: A Systematic Review and Future Perspectives

Valvular heart disease is a common disease often necessitating valve replacement. Mechanical heart valves (MHVs) are often used in younger patients because of their longer durability. Their main disadvantage is the need for lifelong anticoagulation. Warfarin is considered a standard treatment, but it is far from perfect. Direct oral anticoagulants (DOACs) are a new and more patient-friendly alternative to warfarin when anticoagulation is required, but have not yet been approved for the indication of mechanical valves.

EVIDENCE ACQUISITION

A literature search of Pubmed, Embase, Web of Science (Core Collection), and Cochrane Library (from inception to May 2023) was performed using a search string that was well defined and not modified during the study. An extensive overview of the search terms used in each database can be found in the Appendix. Only prospective clinical trials were included in this review. A total of 10 publications were included in this review.

RELEVANCE TO CLINICAL PRACTICE

This systematic review summarizes the different types of DOACs and their possible use in the anticoagulation of mechanical valves. We aim to propose future directions in anticoagulation research for mechanical valves.

CONCLUSIONS

DOAC use in MHVs has been halted due to the failure of both dabigatran and apixaban in two major clinical trials. However, rivaroxaban was successful in two small clinical trials. Ample research is still needed to explore new valve designs as well as new anticoagulation targets.

High Risk of Symptomatic Venous Thromboembolism After Surgery for Spine Metastatic Bone Lesions: A Retrospective Study

BACKGROUND

Cancer and spinal surgery are both considered risk factors for venous thromboembolism (VTE). However, the risk of symptomatic VTE for patients undergoing surgery for spine metastases remains undefined.

QUESTIONS/PURPOSES

The purposes of this study were to: (1) identify the proportion of patients who develop symptomatic VTE within 90-days of surgical treatment for spine metastases; (2) identify the factors associated with the development of symptomatic VTE among patients receiving surgery for spine metastases; (3) assess the association between the development of postoperative symptomatic VTE and 1-year survival among patients who underwent surgery for spine metastases; and (4) assess if chemoprophylaxis increases the risk of wound complications among patients who underwent surgery for spine metastases.

METHODS

Between 2002 and 2014, 637 patients at two hospitals underwent spine surgery for metastases. We considered eligible for analysis adult patients whose procedures were to treat cervical, thoracic, or lumbar metastases (including lymphoma and multiple myeloma). At followup after 90 days and 1 year, respectively, 21 of 637 patients (3%) and 41 of 637 patients (6%) were lost to followup. In general, we used 40 mg of enoxaparin or 5000 IUs subcutaneous heparin every 12 hours. Patients on preoperative chemoprophylaxis continued their initial medication postoperatively. All chemoprophylaxis was started 48 hours after surgery and continued day to day but was discontinued if a bleeding complication developed. Low-molecular-weight heparin (including enoxaparin and dalteparin, in general dosages of respectively 40 mg and 5000 IUs daily) was the most commonly used chemoprophylaxis in 308 patients (48%). Subcutaneous heparin was injected into 127 patients (20%); aspirin was used for 92 patients (14%); and warfarin was administered in 21 patients (3.3%). No form of chemoprophylaxis was prescribed for 89 patients (14%). The primary outcome variable, VTE, was defined as any symptomatic pulmonary embolism (PE) or symptomatic deep venous thromboembolism (DVT) within 90 days of surgery as determined by chart review. The secondary outcome was defined as any documented wound complication within 90 days of surgery that might be attributable to chemoprophylaxis. Statistical analysis was performed using multivariable logistic and Cox regression and Kaplan-Meier.

RESULTS

Overall, 72 of 637 patients (11%) had symptomatic VTE; 38 (6%) developed a PE-eight (1.3%) of which were fatal-and 40 (6%) a DVT. After controlling for relevant confounding variables such as age, the modified Charlson Comorbidity Index, visceral metastases, and chemoprophylaxis, longer duration of surgery was independently associated with an increased risk of symptomatic VTE (odds ratio 1.15 for each additional hour of surgery; 95% confidence interval [CI], 1.04-1.28; p = 0.009). After controlling for relevant confounding variables such as age, the modified Charlson Comorbidity Index, visceral metastases, and primary tumor type, patients with symptomatic VTE had a worse 1-year survival rate (VTE, 38%; 95% CI, 27-49 versus nonVTE, 47%; 95% CI, 42-51; p = 0.044). After controlling for relevant confounding variables, no association was found between wound complications and the use of chemoprophylaxis (odds ratio, 1.34; 95% CI, 0.62-2.90; p = 0.459). The overall proportion of patients who developed a wound complication was 10% (66 of 637), including 1.1% (seven of 637) spinal epidural hematomas.

CONCLUSIONS

The risk of both symptomatic PE and fatal PE is high in this patient population, and those with symptomatic VTE were less likely to survive 1-year than those who did not, though this may reflect overall infirmity as much as anything else, because many of these patients did not die from VTE-related complications. Further study, such as randomized controlled trials with consistent postoperative VTE screening comparing different chemoprophylaxis regimens, are needed to identify better VTE prevention strategies.

LEVEL OF EVIDENCE

Level III, therapeutic study.

High Risk of Venous Thromboembolism After Surgery for Long Bone Metastases: A Retrospective Study of 682 Patients

BACKGROUND

Previous studies have shown that venous thromboembolism (VTE) is a complication associated with neoplastic disease and major orthopaedic surgery. However, many potential risk factors remain undefined.

QUESTIONS/PURPOSES

(1) What proportion of patients develop symptomatic VTE after surgery for long bone metastases? (2) What factors are associated with the development of symptomatic VTE among patients receiving surgery for long bone metastases? (3) Is there an association between the development of symptomatic VTE and 1-year survival among patients undergoing surgery for long bone metastases? (4) Does chemoprophylaxis increase the risk of wound complications among patients undergoing surgery for long bone metastases?

METHODS

A retrospective study identified 682 patients undergoing surgical treatment of long bone metastases between 2002 and 2013 at the Massachusetts General Hospital and Brigham and Women's Hospital. We included patients 18 years of age or older who had a surgical procedure for impending or pathologic metastatic long bone fracture. We considered the humerus, radius, ulna, femur, tibia, and fibula as long bones; metastatic disease was defined as metastases from solid organs, multiple myeloma, or lymphoma. In general, we used 40 mg enoxaparin daily for lower extremity surgery and 325 mg aspirin daily for lower or upper extremity surgery. The primary outcome was a VTE defined as any symptomatic pulmonary embolism (PE) or symptomatic deep vein thrombosis (DVT; proximal and distal) within 90 days of surgery as determined by chart review. The tertiary outcome was defined as any documented wound complication that might be attributable to chemoprophylaxis within 90 days of surgery. At followup after 90 days and 1 year, respectively, 4% (25 of 682) and 8% (53 of 682) were lost to followup. Statistical analysis was performed using multivariable logistic and Cox regression and Kaplan-Meier.

RESULTS

Overall, 6% (44 of 682) of patients had symptomatic VTE; 22 patients sustained a DVT, and 22 developed a PE. After controlling for relevant confounding variables, higher preoperative hemoglobin level was independently associated (odds ratio [OR], 0.75; 95% confidence interval [CI], 0.60-0.93; p = 0.011) with decreased symptomatic VTE risk, the presence of symptomatic VTE was associated with a worse 1-year survival rate (VTE: 27% [95% CI, 14%-40%] and non-VTE: 39% [95% CI, 35%-43%]; p = 0.041), and no association was found between wound complications and the use of chemoprophylaxis (OR, 3.29; 95% CI, 0.43-25.17; p = 0.252).

CONCLUSIONS

The risk of symptomatic 90-day VTE is high in patients undergoing surgery for long bone metastases. Further study would be needed to determine the VTE prevention strategy that best balances risks and benefits to address this complication.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Mobile compression devices and aspirin for VTE prophylaxis following simultaneous bilateral total knee arthroplasty

Recently, Levy et al questioned the effectiveness of mobile compression devices (MCDs) as the sole method of thromboprophylaxis following simultaneous bilateral total knee arthroplasty (TKA). This study's purpose was to assess if the addition of aspirin to MCDs improves venous thromboembolism (VTE) prevention following simultaneous bilateral TKA. Ninety-six patients (192 TKAs) were retrospectively reviewed: 47 patients received MCDs for 10 days and aspirin for 6 weeks postoperatively based on a risk stratification protocol, while 49 patients received warfarin for 4 weeks postoperatively. One symptomatic VTE was noted in the warfarin cohort, while one patient in the MCD/aspirin cohort and three patients in the warfarin cohort were readmitted within 3 months of surgery. In appropriately selected patients, MCDs with aspirin shows promise in VTE prevention following simultaneous bilateral TKA.

The use of warfarin for DVT prophylaxis following hip and knee arthroplasty: how often are patients within their target INR range?

The purpose of this study was to determine the percentage of time that patients are therapeutic when prescribed warfarin for chemical thromboprophylaxis following a hip or knee arthroplasty procedure. One hundred eighty-four patients receiving warfarin for 4weeks postoperatively, dosed using a Web-application accounting for patient demographics, INR levels, and concomitant medication use, were included. Patients with a target INR range between 1.7 and 2.7 were therapeutic for only 54.4% of the time (32.5% subtherapeutic, 13.0% supratherapeutic) while patients with a target INR range between 2.0 and 3.0 were therapeutic for only 45.9% of the time (39.2% subtherapeutic, 14.8% supratherapeutic). Patients receiving warfarin for chemical thromboprophylaxis are within their targeted INR range for only a limited period of time during their postoperative course.

Patient-reported compliance with thromboprophylaxis using an oral factor Xa inhibitor (rivaroxaban) following total hip and total knee arthroplasty

This prospective study examines patient non-compliance (NC) for an oral factor Xa inhibitor (Rivaroxaban) when used as venous thromboembolic (VTE) prophylaxis following lower limb arthroplasty. A total of 3145 patients underwent surgery from May 2010 to December 2011. At 6 weeks patients completed an anonymous self-administered questionnaire. Postoperatively 2947 (94%, 2947/3145) received Rivaroxaban. 2824 (96%, 2824/2947) completed all in-hospital doses. Seven percent (203/2824) of patients did not attend the 6-week follow-up. Two thousand one hundred sixty-three (83%, 2163/2621) completed all prescribed doses, 98 (4%, 98/2621) were NC and 360 (14%, 360/2621) had incomplete data. Gender, age, body mass index and preoperative hemoglobin all correlated with NC (p < 0.05). Type and side of surgery did not correlate with compliance (p > 0.05). Patient-reported NC for Rivaroxaban is 4% which compares favorably to other VTE prophylaxis modalities.

Thrombosis incidence in unilateral vs. simultaneous bilateral total knee arthroplasty with compression device prophylaxis

This study compares the incidence of venous thromboembolic event (VTE) in 55 patients (110 knees) undergoing simultaneous bilateral TKA with 287 patients (287 knees) undergoing unilateral TKA using a mobile compression device as monotherapy prophylaxis in both groups. All patients were clinically evaluated 3months after surgery with symptomatic confirmed VTE as an endpoint. Deep venous thrombosis (DVT) was documented by duplex ultrasound and pulmonary embolism (PE) was documented by spiral CT. The simultaneous bilateral TKA group had 6 VTEs (10.9%) with 2 PEs (3.6%). The unilateral TKA group had 9 VTEs (3.1%), and 0 PE. Patients undergoing simultaneous bilateral TKA yielded more than twice the rate of VTE compared with patients undergoing unilateral TKA using a mobile compression device as sole thromboprophylactic modality.

The efficacy and safety of rivaroxaban for venous thromboembolism prophylaxis after total hip and total knee arthroplasty

Venous thromboembolism (VTE) is a common complication after total hip and total knee arthroplasty. Currently used methods of VTE prophylaxis after these procedures have important limitations, including parenteral administration, and unpredictable plasma levels requiring frequent monitoring and dose adjustment leading to decreased patient compliance with recommended guidelines. New oral anticoagulants have been demonstrated in clinical trials to be equally efficacious to enoxaparin and allow for fixed dosing without the need for monitoring. Rivaroxaban is one of the new oral anticoagulants and is a direct factor Xa inhibitor that has demonstrated superior efficacy to that of enoxaparin. However, the data also suggest that rivaroxaban has an increased risk of bleeding compared to enoxaparin. This paper reviews the available data on the efficacy and safety of rivaroxaban for VTE prophylaxis after total hip and total knee arthroplasty.

Apixaban: a review of its use in the prevention of venous thromboembolism after knee or hip replacement surgery

Apixaban (Eliquis™) is an orally active and selective direct inhibitor of factor Xa indicated for twice-daily use in the EU for the prevention of venous thromboembolism (VTE) in adults who have had knee or hip replacement surgery. In this article, the pharmacological, clinical efficacy and tolerability data relevant to the use of apixaban in this indication are reviewed. Oral apixaban is a generally effective and well tolerated thromboprophylactic agent for use after major orthopaedic surgery. In the large, randomized, double-blind, phase III, noninferiority trials known as ADVANCE-2 and -3, apixaban 2.5 mg twice daily initiated after surgery was generally more effective in preventing VTE in patients undergoing knee or hip replacement surgery than subcutaneous enoxaparin sodium initiated before surgery at the EU recommended dosage of 40 mg once daily, with apixaban conferring this benefit without significantly increasing the risk of bleeding. However, when the same apixaban regimen was compared with the US recommended dosage regimen of subcutaneous enoxaparin sodium (30 mg twice daily, initiated after surgery) in patients undergoing knee replacement surgery in the similarly designed ADVANCE-1 trial, the thromboprophylactic efficacy of apixaban did not meet primary endpoint noninferiority criteria, although apixaban was associated with fewer major or clinically relevant nonmajor bleeds (composite endpoint) than this enoxaparin sodium regimen. Additional comparative efficacy and tolerability data are required to definitively position apixaban with respect to other anticoagulants, including rivaroxaban and dabigatran etexilate. In the meantime, currently available clinical data indicate that apixaban is an emerging option for the prevention of VTE in patients undergoing knee or hip replacement surgery.

The year in Cardiothoracic and Vascular Anesthesia: selected highlights from 2011

There have been rapid advances in oral anticoagulation. The oral factor Xa inhibitors rivaroxaban and apixaban and the oral direct thrombin inhibitor dabigatran recently have been rigorously evaluated. These novel anticoagulants will usher in a new paradigm for perioperative anticoagulation. Perioperative blood conservation in cardiac surgery recently has been highlighted in the updated guidelines by the Society of Cardiovascular Anesthesiologists and the Society of Thoracic Surgeons. These recommendations reflect a comprehensive evaluation of the recent evidence to optimize transfusion practice. Transcatheter mitral valve repair continues to mature. Transcatheter aortic valve implantation for aortic stenosis has entered the clinical mainstream, with randomized trials showing its superiority over medical management and its equivalency to surgical valve replacement in high-risk patients. This transformational technology represents a major leadership opportunity for the cardiac anesthesiologist. Minimally invasive valve surgery has shown effectiveness in high-risk patients. Radial access is equivalent to femoral access for percutaneous coronary intervention in acute coronary syndromes but significantly reduces the risk of local vascular complications. Recent trials have further clarified the roles of medical therapy, percutaneous coronary intervention, and coronary artery bypass surgery in patients with significant coronary artery disease and left ventricular dysfunction. The past year has witnessed major advances in cardiovascular practice with new drugs, new devices, and new guidelines. The coming year most likely will advance these achievements to enhance the care of patients.