Rivaroxaban and dabigatran etexilate: two new oral anticoagulants for extended postoperative prevention of venous thromboembolism after elective total hip arthroplasty

Comparative Incidence of Postoperative Hemorrhage in Vitreoretinal Surgery in Patients on Anti-Coagulants

BACKGROUND AND OBJECTIVE

Data regarding hemorrhagic complications of direct oral anticoagulants (DOACs) and vitreoretinal surgery are limited.

PATIENTS AND METHODS

Multicenter analysis of longitudinal, aggregated electronic health records of patients undergoing pars plana vitrectomy (PPV) with no prior history of ocular hemorrhage. Retrospective analysis of patients undergoing PPV between January 1, 2013, and December 31, 2019. The main outcomes were development of postoperative hemorrhagic complications within 1 month following vitreoretinal surgery.

RESULTS

A total of 58,131 eyes underwent PPV, with 2,956 (5.1%) on anticoagulant medication prior to surgery. Eight hundred twenty-eight eyes (1.4%) developed a postoperative hemorrhage. Of eyes with anticoagulation use, 50 of 2,956 (1.29%) developed a hemorrhage, whereas 778 of 55,175 (1.41%) of the eyes with no prior anticoagulation use developed a postoperative hemorrhage (P = .2107).

CONCLUSION

Use of DOACs prior to vitreoretinal surgery does not appear to be associated with increased rates of postoperative intraocular hemorrhage. [Ophthalmic Surg Lasers Imaging Retina. 2021;52:374-379.].

Long-term outcome after mitral valve replacement using biological versus mechanical valves

BACKGROUND

This study compared long-term outcomes of biological and mechanical mitral valve replacement (MVR) in patients requiring replacement of the mitral valve where repair was not feasible.

METHODS

A single-centre registry of patients receiving MVR between 2005 and 2015 was established. Thirty-day mortality and long-term outcomes were analysed and compared.

RESULTS

Three hundred twenty four patients underwent MVR (265 biological; 59 mechanical valves). Patients receiving biological valves were older (p < 0.001), had a higher log EuroSCORE (p < 0.001) and received less minimally invasive surgery (p < 0.001). Immediate procedural mortality was 1.9%, which only occurred in the biological valve group. At 30 days, 9.0% of patients had died, 4.0% experienced stroke, 8.0% received a pacemaker and 10.5% suffered an acute renal failure. The rate of re-thoracotomy (14.2%) was lower in the biological (12.5%) than in the mechanical valve group (22.0%; adjOR 0.45 [0.20-1.00]; p = 0.050). Frequent long-term complications were stroke (9.2%) and bleeding (4.8%), with bleeding complications being higher in the mechanical valve group (p = 0.009). During the follow-up period biological valves showed a numerically higher survival rate during the first years, which shifted after 3 years in favour of mechanical valves. At 10 years, survival rates were 62.4% vs. 77.1% in the biological and mechanical valve groups (p = 0.769). Hazard ratio after adjustment was 0.833 (95% CI 0.430-1.615).

CONCLUSION

These data confirm that mechanical valve implantation is associated with an increased risk of bleeding. While there was a potential survival benefit during the first years after surgery for patients receiving a biological valves the difference became insignificant after a follow-up of 10 years.

Rivaroxaban versus enoxaparin for the prevention of venous thromboembolism after total knee arthroplasty: A meta-analysis

OBJECTIVE

This article analyzed the clinical efficacy and tolerability of rivaroxaban and enoxaparin in patients undergoing total knee arthroplasty (TKA) surgery.

METHODS

Five randomized, controlled clinical trials on rivaroxaban versus enoxaparin in patients who underwent TKA were identified and included in this meta-analysis.

RESULTS

The meta-analysis indicated that rivaroxaban prophylaxis was associated with lower rates of symptomatic venous thromboembolism (VTE) (relative risk[RR]:0.55; 95% confidence interval [CI]: 0.35-0.86; P = .009), symptomatic deep vein thrombosis (DVT) (RR 0.44, 95% CI 0.25-0.80, P = .007), asymptomatic DVT (RR: 0.57; 95% CI: 0.37-0.89; P = .01), distal DVT (RR: 0.62; 95% CI: 0.45-0.85; P = .003) and proximal DVT (RR: 0.42; 95% CI: 0.24-0.75; P = .004). Compared with the enoxaparin group, the incidence of symptomatic pulmonary embolism (PE) (RR: 0.48; 95% CI: 0.19-1.24; P = .13) in the rivaroxaban group was not significantly different. A nonsignificant trend towards all-cause death (RR: 0.38; 95% CI: 0.03-4.92; P = .46) or major bleeding (RR: 1.59; 95% CI: 0.77-3.27; P = .21) risk between rivaroxaban and enoxaparin prophylaxis was found.

CONCLUSION

Compared with the enoxaparin group, the group using rivaroxaban after TKA had a significantly lower rate of symptomatic VTE, symptomatic DVT, asymptomatic DVT, distal DVT, and proximal DVT. Our study shows that rivaroxaban after TKA is more effective than enoxaparin and did not increase major bleeding or all-cause mortality.

Activated Factor X Induces Endothelial Cell Senescence Through IGFBP-5

Uncontrolled coagulation contributes to the pathophysiology of several chronic inflammatory diseases. In these conditions, senescent cells are often observed and is involved in the generation of inflammation. The coincidence of hyper-coagulation, cell senescence, and inflammation suggests the existence of a common underlying mechanism. Recent evidence indicates that activated coagulation factor X (FXa) plays a role in the processes beyond blood coagulation. This non-hematologic function entails the mediation of inflammation and tissue remodeling. We therefore tested the hypothesis that FXa induces cell senescence resulting in tissue inflammation and impaired tissue regeneration. Human umbilical vein endothelial cells were stimulated with FXa for 14 days. The proliferation of cells treated with FXa was significantly smaller, and the fraction of senescence-associated β-galactosidase-positive cells was increased as compared to the control group. RT-qPCR array revealed that FXa increased the expression of IGFBP-5, EGR-1, p53, and p16^INK4a. Inhibition of FXa by a direct FXa inhibitor, rivaroxaban, or IGFBP-5 by siRNA decreased FXa-induced cell senescence, restoring cell proliferation. Moreover, in an ischemic hind limb mouse model, FXa inhibited neovascularization by endothelial progenitor cell. However, rivaroxaban significantly restored FXa-induced impaired angiogenesis. In summary, FXa induced endothelial cell senescence through IGFBP-5, resulting in impaired angiogenesis.

Rivaroxaban, a factor Xa inhibitor, improves neovascularization in the ischemic hindlimb of streptozotocin-induced diabetic mice

Background

Factor Xa inhibitor is used for preventing venous thromboembolism (VTE) in adult patients receiving orthopedic operation. However, the role of factor Xa inhibitor, rivaroxaban, in angiogenesis is still unknown.

Methods and results

Streptozotocin (STZ)–induced diabetic mice with model of hind-limb ischemia, were divided into non-diabetic control, diabetic control, and low- and high-dose rivaroxaban treatment groups, in order to evaluate the effect of rivaroxaban in angiogenesis. Doppler perfusion imaging showed that blood flow recovery was significantly increased, and more capillary density occurred in the rivaroxaban treatment group. In vitro studies, human endothelial progenitor cells (EPCs) treated with rivaroxaban had significant functional improvement in migration and senescence under hyperglycemic conditions. Rivaroxaban also increased endothelial nitric oxide synthase (eNOS) as well as vascular endothelial growth factor (VEGF) expressions in hyperglycemia-stimulated EPCs.

Conclusions

Rivaroxaban promoted vessel formation in diabetic mice and improved endothelial progenitor cell function under hyperglycemic conditions. These effects may be associated with enhancement of expression of eNOS and VEGF.

Wound problems following hip arthroplasty before and after the introduction of a direct thrombin inhibitor for thromboprophylaxis

In the United Kingdom, national guidelines have stated that patients undergoing elective hip surgery are at increased risk for venous thromboembolic events (VTE) following surgery and have recommended thromboprophylaxis for 28-35 days (1, 2). Studies of direct thrombin inhibitors have hitherto concentrated on major bleeding. We prospectively assessed wound discharge in patients who underwent hip arthroplasty and who received oral dabigatran postoperatively between March 2010 and April 2010 (n=56). We compared these results to a retrospective matched group of patients who underwent similar operations six months earlier, at which time all patients were given subcutaneous dalteparin routinely postoperatively until discharge, and then discharged home on 150 mg aspirin daily for 6 weeks (n=67). Wound discharge after 5 days was significantly higher in the patients taking dabigatran (32% dabigatran n=18, 10% dalteparin n=17, p=0.003) and our rate of delayed discharges due to wound discharge significantly increased from 7% in the dalteparin group (n=5) to 27% for dabigatran (n=15, p=0.004). Patients who received dabigatran were more than five times as likely to return to theatre with a wound complication compared with those who received dalteparin (7% dabigatran n=4, vs. 1% dalteparin n=1), but this was not statistically significant (p=0.18). We now administer dalteparin until the wound is dry and then start dabigatran. Our study demonstrates the need for further clinical studies regarding wound discharge and direct thrombin inhibitors.

Innovations in total knee replacement: new trends in operative treatment and changes in peri-operative management

The human knee joint can sustain damage due to injury, or more usually osteoarthritis, to one, two or all three of the knee compartments: the medial femorotibial, the lateral femorotibial and the patellofemoral compartments. When pain associated with this damage is unmanageable using nonsurgical techniques, knee replacement surgery might be the most appropriate course of action. This procedure aims to restore a pain-free, fully functional and durable knee joint. Total knee replacement is a well-established treatment modality, and more recently, partial knee replacement-more commonly known as bi- or unicompartmental knee replacement-has seen resurgence in interest and popularity. Combined with the use of minimally invasive surgery (MIS) techniques, gender-specific prosthetics and computer-assisted navigation systems, orthopaedic surgeons are now able to offer patients knee replacement procedures that are associated with (1) minimal risks during and after surgery by avoiding fat embolism, reducing blood loss and minimising soft tissue disruption; (2) smaller incisions; (3) faster and less painful rehabilitation; (4) reduced hospital stay and faster return to normal activities of daily living; (5) an improved range of motion; (6) less requirement for analgesics; and (7) a durable, well-aligned, highly functional knee. With the ongoing advancements in surgical technique, medical technology and prosthesis design, knee replacement surgery is constantly evolving. This review provides a personal account of the recent innovations that have been made, with a particular emphasis on the potential use of MIS techniques combined with computer-assisted navigation systems to treat younger, more physically active patients with resurfacing partial/total implant knee arthroplasty.

Cardiac crossroads: deciding between mechanical or bioprosthetic heart valve replacement

Nearly 15 million people in the United States suffer from either aortic or mitral valvular disease. For patients with severe and symptomatic valvular heart disease, valve replacement surgery improves morbidity and mortality outcomes. In 2009, 90,000 valve replacement surgeries were performed in the United States. This review evaluates the advantages and disadvantages of mechanical and bioprosthetic prosthetic heart valves as well as the factors for consideration in deciding the appropriate valve type for an individual patient. Although many caveats exist, the general recommendation is for patients younger than 60 to 65 years to receive mechanical valves due to the valve's longer durability and for patients older than 60 to 65 years to receive a bioprosthetic valve to avoid complications with anticoagulants. Situations that warrant special consideration include patient co-morbidities, the need for anticoagulation, and the potential for pregnancy. Once these characteristics have been considered, patients' values, anxieties, and expectations for their lifestyle and quality of life should be incorporated into final valve selection. Decision aids can be useful in integrating preferences in the valve decision. Finally, future directions in valve technology, anticoagulation, and medical decision-making are discussed.

Newer anticoagulants in 2009

Several newer anticoagulants are under clinical development. Recently two of them, Dabigatran etexilate/Pradaxa. and Rivaroxaban/Xarelto obtained marketing authorization in Europe and Canada for the prevention of thromboembolic events following major orthopedic surgery such as total hip and knee replacement. The results of Phase III clinical studies in thromboprophylaxis in major orthopedic surgery are highlighted and discussed in detail. Ongoing Phase II and III clinical trials assess their efficacy in the secondary prevention and treatment of deep vein thrombosis and pulmonary embolism, and in the long-term prevention of stroke in patients with non-valvular atrial fibrillation and in combination with aspirin and clopidogrel in patients with acute coronary syndromes. Many other small antithrombotic molecules including a new generation of low molecular weight heparins, are currently in different stages of clinical development. In addition to being administered orally, the newer anticoagulant agents have a more balanced benefit/risk ratio and wider therapeutic window. They have a rapid onset of action, a predictable anticoagulant effect that does not require routine laboratory monitoring. They have minor food and drug interactions, including those with cytochrome P450 and P.gp. They are highly specific and targeted to a single coagulation factor, and could carry similar or less hemorrhagic risks compared to the older anticoagulant agents. Finally, they may be used in a broader variety of patients, especially the medically ill patients with advanced cancer, and the elderly without any dosage adjustment, regardless of the patient age, gender, body weight, or in patients with mild renal impairment. Their use in the general world will hopefully confirm the promising results of clinical trials.

Unanswered questions, unmet needs in venous thromboprophylaxis

Although significant progress has been made over the past 25 years in preventing thromboembolic disease in patients undergoing total hip and total knee arthroplasty, important questions remain unanswered. Few would debate the need to seek a balance between maximal antithrombotic efficacy and minimal bleeding in choosing a thromboprophylactic strategy, but there is less agreement as to how efficacy should be defined, and whether efficacy and safety (however each is defined) are intrinsic to the thromboprophylactic agent chosen or depend as well on exogenous factors, ranging from the timing of drug administration to surgical technique. Differences between recent guidelines from the American Academy of Orthopaedic Surgeons (AAOS) and the American College of Chest Physicians (ACCP) illustrate these unanswered questions. The AAOS guidelines focus solely on preventing symptomatic pulmonary embolism and ignores the importance of other acute and chronic manifestations of venous thromboembolic disease. The ACCP, on the other hand, does consider these other manifestations of venous thromboembolic disease, and thus reaches very different conclusions about what constitutes effective thromboprophylaxis. Despite these questions and uncertainties, there are fundamental truths: (1) venous thromboembolism (VTE) is a known and serious complication of total joint arthroplasty, and (2) evidence-based thromboprophylaxis works. Gaps between guideline-recommended and actual orthopedic practice must be reduced.