Background: The risk of ischaemic stroke in patients with atrial fibrillation (AF) and mechanical heart valve (MHV) prostheses can be reduced by oral anticoagulation (OAC), which increases the risk of serious bleeding. The aims of this thesis were [1] to find out how effective and safe warfarin is where treatment quality is high, i.e. Sweden, with proportion of time that patients spend within the therapeutic range (TTR) &gt;70%, [2] whether there is evidence for administering low-molecular-weight heparin (LMWH) during temporary interruptions of OAC (bridging therapy), and whether non-vitamin K-dependent oral anticoagulants (NOACs) as a group, [3] or individually, [4] are more effective and safer than warfarin when used for stroke prevention in patients with AF. Materials and methods: All four studies were retrospective, based on the Swedish anticoagulation register Auricula, and done with merging of data from some or all of the National Patient Register, the Prescribed Drug Register, the Swedish Stroke Register (Riksstroke), and the Cause of Death Register. In studies 2–4, propensity score matching was performed to obtain treatment groups with similar risk profiles. Outcomes were defined as haemorrhages or thromboses requiring specialist care, or death. Haemorrhages were intracranial, gastrointestinal, or other. Thromboses were ischaemic stroke, systemic embolism, myocardial infarction, or venous thromboembolism (VTE). Study 1 described all patients on warfarin during 2006–2011, which was before the introduction of NOACs. Study 2 was a cohort study of all patients who had a planned interruption of warfarin during the same period. Study 3 included all 49,011 patients starting OAC for stroke prevention due to AF between 1 July 2011 and 31 December 2014, and study 4 all 64,382 patients with the same indication between 1 January 2013 and 31 December 2015. Results: Study 1 showed that for the 77,423 patients on warfarin with 217,804 treatment years, TTR was 77.4% for patients with AF, 74.5% with MHV, and 75.9% with VTE. Annual rates of intracranial bleeding were 0.38%, 0.51%, and 0.30%. In study 2, with 14,556 warfarin interruptions, the 30-day risk of a bleeding requiring specialist care was 0.64% for LMWH treated and 0.46% for controls. For patients with VTE as indication for OAC, bleeding rate with LMWH was significantly higher at 0.85% vs. 0.16% (hazard ratio 5.24, 95% confidence interval 1.39–19.77), but with no difference for patients with MHV or AF. The incidence of ischaemic complications was higher in the LMWH bridging group overall and for patients with MHV and AF, but not for patients with VTE. In study 3, for the 12,694 patients starting NOAC (10,392 treatment years) or matched warfarin patients (9,835 treatment years, TTR 70%) due to AF, annual incidence of ischaemic stroke and systemic embolism did not differ between the groups (1.35% vs. 1.58%), but risks of major bleedings and intracranial bleedings were significantly lower: 2.76% vs. 3.61% and 0.40% vs. 0.69%. In study 4, patients on individual NOACs (6,574 dabigatran, 8,323 rivaroxaban, 12,311 apixaban) were compared to 37,174 patients starting warfarin (in total 81,176 treatment years). No NOAC showed any difference in risk of ischaemic stroke or systemic embolism, but there were fewer intracranial bleedings, serious bleedings overall, and deaths for dabigatran and apixaban compared to warfarin. For patients starting rivaroxaban the risk of gastrointestinal bleeding was higher than for matched warfarin counterparts, with no significant differences in other bleeding risks, or mortality. Conclusions: Swedish warfarin treatment shows TTR levels that are high by international standards, correlating to low incidences of ischaemic and haemorrhagic events. LMWH bridging has not been proven beneficial, even for patients with MHV, meaning that bridging in general cannot be recommended. NOACs as a group were safer than high-quality warfarin treatment. Efficacy did not differ, even when comparing individual NOACs to warfarin, but there were fewer bleedings on dabigatran and apixaban. Although not more efficient than warfarin with a high TTR, NOACs should be the recommended first choice for OAC in AF, on the merit of lower bleeding risks. / <p>Finansiär: Forskning och Utveckling, Region Västernorrland</p>

Background: Guidelines recommend the use of multiple pharmacologic agents and/or mechanical compressive devices for prevention of venous thromboembolism, but preference for any specific agent is no longer given in regard to safety or efficacy. Objective: To compare postoperative bleeding rates in patients receiving enoxaparin, rivaroxaban, or aspirin for thromboprophylaxis after undergoing elective total hip arthroplasty or total knee arthroplasty. Methods: This retrospective cohort analysis evaluated patients who received thromboprophylaxis with either enoxaparin, rivaroxaban, or aspirin. All data were collected from the electronic medical record. The primary outcome was any postoperative bleeding. Results: A total of 1244 patients were included with 366 in the aspirin, 438 in the enoxaparin, and 440 in the rivaroxaban arms. Those who received aspirin or enoxaparin were less likely to experience any bleeding compared to those patients who received rivaroxaban (P <.05). There was also a lower rate of major bleeding in these groups, but the differences were not significant. Conclusions: Aspirin and enoxaparin conferred similar bleeding risks, and both exhibited less bleeding than patients who received rivaroxaban.

Background: The Regulation of Coagulation in Orthopedic Surgery to Prevent Deep Venous Thrombosis and Pulmonary Embolism (RECORD) 1 to 4 trials compared rivaroxaban 10 mg daily with commonly used doses of enoxaparin and demonstrated similar rates of VTE and bleeding. Objective: To evaluate bleeding events between patients who received enoxaparin or rivaroxaban for prevention of venous thromboembolism (VTE) following total hip arthroplasty (THA) or total knee arthroplasty (TKA). Methods: Retrospective cohort that compared patients undergoing THA and TKA who received enoxaparin (enoxaparin) with those who received rivaroxaban (rivaroxaban) and also with those who received enoxaparin in the RECORD 1 to 4 trials (enoxaparin RECORD). The primary outcome was any postoperative bleeding, defined as a composite of major and clinically relevant nonmajor bleeding based on the definitions in the RECORD 1 to 4 trials. Results: There was a lower rate of any postoperative bleeding (2.2% vs 6.8%, P = 0.004) in patients who received enoxaparin compared with rivaroxaban, and bleeding rates between the enoxaparin group and the enoxaparin RECORD groups were similar (2.2% vs 2.5%, P = 0.085). Major bleeding in the enoxaparin group (0.2%) was not significantly different from that in the rivaroxaban group (1.4%, P = 0.12) or the RECORD group (0.2%, P = 0.93). Clinically relevant nonmajor bleeding was also lower in the enoxaparin group compared with the rivaroxaban group (2.0% vs 5.5%, P = 0.012). Conclusions: The use of enoxaparin for VTE prophylaxis following THA and TKA was associated with a lower rate of the primary outcome (any postoperative bleeding) compared with the use of rivaroxaban in a similar cohort of patients.

BACKGROUND:Anticoagulation with vitamin K antagonists such as warfarin has historically been used for the long term management of patients with thromboembolic disease. However, these agents have a slow onset of action which requires bridging therapy with heparin and its analogues, which are available only in parenteral route. To overcome these limitations, new oral anticoagulants such as factor Xa inhibitors and direct thrombin inhibitors have been developed. The aim of this article is to systematically review the phase 3 clinical trials of new oral anticoagulants in common medical conditions.METHODS:We searched PubMed (Medline) from January 2007 to February 2013 using "Oral anticoagulants", "New oral anticoagulants", "Randomized controlled trial", "Novel anticoagulants", "Apixaban", "Rivaroxaban", "Edoxaban", "Dabigatran etexilate", "Dabigatran" and a combination of the above terms. The available evidence from the phase 3 RCTs was summarized on the basis of individual drug and the medical conditions categorized into "atrial fibrillation", "acute coronary syndrome", "orthopedic surgery", "venous thromboembolism" and "medically ill patients".RESULTS:Apixaban, rivaroxaban and dabigatran have been found to be either non-inferior or superior to enoxaparin in prophylaxis of venous thromboembolism in knee and hip replacement with similar bleeding risk, superior to warfarin for stroke prevention in atrial fibrillation with significant reduction in the risk of major bleeding, non-inferior to aspirin for reducing cardiovascular death and stroke in acute coronary syndrome with significant increase in the risk of major bleed. Rivaroxaban and dabigatran are also superior to the conventional agents in the management of symptomatic venous thromboembolism. However, compared to enoxaparin, apixaban and rivaroxaban use lead to significantly increased bleeding risk in medically ill patients. Additional studies evaluating the specific reversal agents of these new drugs for the management of life-threatening bleeding or other adverse effects are necessary.CONCLUSION:Considering their pharmacological properties, their efficacy and bleeding complications, the new oral agents offer a net favourable clinical profile in orthopedic surgery, atrial fibrillation, acute coronary syndrome and increase the risk of bleeding in critically ill patients. Further studies are necessary to determine the long term safety and to identify the specific reversal agents of these new drugs.

The relative risk of major gastrointestinal bleeding (GIB) among different direct oral anticoagulants (DOACs) is debatable. Randomized controlled trials (RCTs) comparing DOACs with each other are lacking. We performed network meta-analysis to assess whether the risk of major GIB differs based on type and dose of DOAC. Literature search of PubMed, EMBASE and Cochrane databases from inception to August 2019, limited to English publications, was conducted to identify RCTs comparing DOACs with warfarin or enoxaparin for any indication. Primary outcome of interest was major GIB risk. We used frequentist network meta-analysis through the random-effects model to compare DOACs with each other and DOACs by dose to isolate the impact on major GIB. Twenty-eight RCTs, including 139 587 patients receiving six anticoagulants, were selected. The risk of major GIB for DOACs was equal to warfarin. Comparison of DOACs with each other did not show risk differences. After accounting for dose, rivaroxaban 20 mg, dabigatran 300 mg and edoxaban 60 mg daily had 47, 40 and 22% higher rates of major GIB versus warfarin, respectively. Apixaban 5 mg twice daily had lower major GIB compared to dabigatran 300 mg (OR, 0.63; 95% CI, 0.44-0.88) and rivaroxaban 20 mg (OR, 0.60; 95% CI, 0.43-0.83) daily. Heterogeneity was low, and the model was consistent without publication bias (Egger's test: P = 0.079). All RCTs were high-quality with low risk of bias. DOACs at standard dose, except apixaban, had a higher risk of major GIB compared to warfarin. Apixaban had a lower rate of major GIB compared to dabigatran and rivaroxaban.

BACKGROUND: Current guidelines give class I recommendations for uninterrupted use of dabigatran rivaroxaban as an alternative to vitamin K antagonist (VKA) in patients of atrial fibrillation (AF) who are undergoing catheter ablation. The recent randomized controlled trials have shown similar efficacy of novel oral anticoagulants when compared to VKA in these patients. We sought to perform a meta-analysis with a focus on subgroup analysis of novel oral anticoagulants. METHODS: We searched PubMed, Clinical trials registry and the Cochrane Center Register of Controlled Trials were searched through August 2020. Six RCTs studies (n = 2260) comparing the use of NOACs versus VKA in patients with AF undergoing catheter ablation were included. The odds ratio (OR) with 95% confidence interval was computed and P < 0.05 was considered as a level of significance. Major adverse cardiac events (MACE) were considered as a primary endpoint. RESULTS: Our results showed a significant difference in MACE between NOACs and VKA [OR 0.57 (0.37-0.88); P = 0.01] and in major bleeding events [OR 0.55 (0.35-0.86); P = 0.009], which is mainly derived from the use of dabigatran. No significant difference in MACE or major bleeding events was found on the subgroup analysis of rivaroxaban and apixaban over VKA therapy. CONCLUSION: Uninterrupted use of NOACs is safe and effective alternative for the prevention of cerebral thromboembolism and reducing the risk of major bleeding in patients undergoing catheter ablation of AF. However, the individual subgroup analysis showed that only dabigatran is superior to VKA in terms of reducing MACE through a reduction in major bleeding. The rivaroxaban, apixaban and edoxaban are non-inferior to VKA therapy based on these results. Further studies are needed to generalize these recommendations in morbidly obese patients.