Comparison of 5-mg and 10-mg loading doses in initiation of warfarin therapy

An Experimental Study to Assess the Ecotoxicity of Warfarin and Tinzaparin on Meiobenthic Amphipods: Original Taxonomic Data from Saudi Arabia and Computational Modeling

In the current research, we examined the effects of warfarin (W1 = 5 mg/L and W2 = 25 mg/L) and tinzaparin (T1 = 5 mg/L and T2 = 25 mg/L) on meiofauna using microcosms. These microcosms were intentionally contaminated with both anticoagulants for one month. The findings indicated that nematodes and amphipods demonstrated the greatest resistance to the two anticoagulants evaluated. Specifically, the number of amphipods increased after exposure to the treatment that included T2. Following the separate introduction of each drug, amphipods displayed a taxonomic restructuring, with a more significant impact observed from T2 and T2W1. Results were derived from multivariate analyses of a compilation of sensitive amphipod taxa in response to tinzaparin and warfarin. In contrast, different species were identified as positive indicators for tinzaparin. Ultimately, the similarity between the control amphipod replicates and those subjected to mixed anticoagulants (T1W1 and T2W2) suggests that warfarin may have reduced the toxicity of tinzaparin. Additionally, the computational study indicated that warfarin interacts with 4XNN and forms strong molecular interactions with several key residues, which contribute to the toxicokinetic characteristics observed in the empirical findings.

Antithrombotic resumption after middle meningeal artery embolization or surgery for chronic subdural hematoma: a systematic review and meta-analysis

BACKGROUND

The periprocedural management of antithrombotic medications in patients with chronic subdural hematoma (cSDH) after middle meningeal artery embolization (MMAE) or surgical evacuation is uncertain.

METHODS

A systematic review was conducted across Medline, Embase, and Web of Science databases. We pooled proportions and risk ratios (RRs) for the meta-analysis with the corresponding 95% CIs. Systemic and intracranial (including recurrence) bleeding complications and thromboembolic events were evaluated.

RESULTS

Of the 16 included studies with 4606 patients, 1784 were receiving antithrombotic medications. Antithrombotic therapy was resumed in 1231 patients (69.0%). Bleeding complications were similar between patients in whom antithrombotic therapy was resumed (14.1%, 95% CI 9.7% to 20.2%) and in those in whom it was discontinued (15.4%, 95% CI 7.4% to 29.3%). After MMAE, patients had similar rates of bleeding events (12.1%, 95% CI 4.9% to 27.0%) to patients with overall treated cSDH, and recurrence (RR 2.28, 95% CI 0.46 to 11.37) and reoperation (RR 1.07, 95% CI 0.40 to 2.917) risks were similar between the resumed and discontinued groups. Thromboembolic complications were significantly higher in the discontinued group (12.6%, 95% CI 6.5% to 23.0%) than in the resumption group (3.5%, 95% CI 1.8% to 6.9%). Earlier resumption (1 week to 1 month) was associated with a lower thromboembolic risk without increasing bleeding complications.

CONCLUSIONS

Post-procedural antithrombotic resumption may reduce thromboembolic events without significantly increasing bleeding risk. Early resumption of antithrombotics post-MMAE appears to be safe, although further data are required to confirm this observation. Future studies should aim to better define patient characteristics influencing decision-making in this context.

Examining the controversies in venous thromboembolism prophylaxis for vascular surgery patients: A critical review

BACKGROUND

Venous thromboembolism (VTE) is a significant concern in vascular surgery due to its potentially severe consequences. Effective prophylactic measures are essential to minimize the risks associated with VTE. However, considerable controversy remains regarding the optimal strategies for VTE prevention in patients undergoing vascular procedures.

METHODS

This review critically analyzes key clinical research, guidelines, and expert opinions to explore the advantages and limitations of various VTE prophylaxis approaches. The pharmacological and mechanical methods are explored, with a focus on balancing the risk of VTE against the potential for bleeding complications, particularly in high-risk patients.

RESULTS

The review addresses controversial issues such as the choice of anticoagulants, dosage, timing, and duration of prophylaxis. The lack of consensus in existing guidelines and the variability in clinical practice regarding VTE prevention in vascular surgery patients is highlighted. The role of patient-specific risk factors, including the use of intraoperative anticoagulation and bleeding risks, is also examined.

CONCLUSION

This review provides a comprehensive evaluation of VTE prophylaxis strategies in vascular surgery, emphasizing the need for individualized, evidence-based approaches. Clarifying these controversies is crucial for optimizing patient outcomes and minimizing both thrombotic and hemorrhagic complications.

Chinese stroke patients with atrial fibrillation used Robert's age-adjusted warfarin loading protocol obtained good INR results within therapeutic range

To assess whether Roberts' age-adjusted warfarin loading protocol is effective in Chinese patients and whether the SAMeTT2R2 score can predict international normalized ratio (INR) control. Roberts' protocol for warfarin titration was applied to patients with non-valvular atrial fibrillation (NVAF) complicated with ischemic stroke at the Department of Neurology between 2014 and 2019. Clinical and sociodemographic variables were recorded. A minimum of 1-year follow-up was used to calculate the time in therapeutic range (TTR) of the INR. A total of 94 acute ischemic stroke patients with NVAF were included in the study. Seventy-seven (81.9%) of the patients had attained stable INR (2.0-3.0) at the fifth dose, and 90.0% of the patients had achieved stable INR on the ninth day. Seventeen (18.1%) of the patients had an INR > 4 during dose-adjustment period. Patients with INR > 4 had significantly lower body weight (53.8 vs. 63.1 kg, P = 0.014), lower rate of achievement of stable INR (35.3% vs. 92.2%, P = 0.000), and lower rate of TTR ≥ 65% (23.5% vs. 70.1%, P = 0.001), but with no significant increase in bleeding risk. A total of 89 patients underwent long-term INR follow-up, of which 58 (65.2%) patients achieved TTR ≥ 65%. Patients with poor TTR had significantly lower body weight (56.3 vs. 63.7 kg, P = 0.020) and lower rate of stable INR achievement (64.5% vs. 89.7%, P = 0.002). All 94 patients had SAMeTT2R2 score ≥ 2. There was no linear association between SAMeTT2R2 score and the rate of TTR ≥ 65% (Ptrend = 0.095). Chinese ischemic stroke patients with NVAF on warfarin can safely and quickly achieve therapeutic INR using Roberts' age-adjusted protocol and can obtain a good TTR. Lower body weight may be a predictor of poor TTR and INR > 4. Patients who have not attained stable INR after adjusting the dose five times are at high risk for poor TTR. SAMeTT2R2 score may not predict TTR in Chinese ischemic stroke patients with NVAF.

Comparison of Warfarin Initiation at 3 mg Versus 5 mg for Anticoagulation of Patients with Mechanical Mitral Valve Replacement Surgery: A Prospective Randomized Trial

Background

The increased warfarin sensitivity observed after mechanical mitral valve replacement (MVR) operations dictates clinical discretion in warfarin dose initiation. Evidence is still lacking with regard to anticoagulation management of MVR patients.

Objective

This study aimed to compare initiating warfarin at the recommended dosing regimen versus empirically lowered doses intended to account for the variation in warfarin sensitivity.

Methods

A prospective, single-blind, randomized, comparative study was conducted in postoperative MVR patients. Patients were randomly assigned to either the 5 mg group (n = 25) or the 3 mg group (n = 25) and were initiated on a 5 or 3 mg warfarin dose, respectively. Time to target international normalized ratio (INR), time in therapeutic range, occurrence of bleeding/thromboembolic events, and cost of bridging with enoxaparin were assessed for both groups.

Results

Target INR was achieved earlier in the 5 mg group than in the 3 mg group (p = 0.033), with a mean ± SD of 5.3 ± 2.0 and 6.6 ± 2.0, respectively (95% confidence interval of the mean difference 1.022–1.890). Bleeding events did not differ significantly between the two groups. The cost of enoxaparin consumption per patient was significantly higher in the 3 mg group versus the 5 mg group (p = 0.002).

Conclusions

The initiation of warfarin at a 5 mg dose in MVR patients was more efficacious than the 3 mg dose in terms of time to reach the target INR. Moreover, the cost of enoxaparin bridging was significantly reduced with a 5 mg warfarin initiation dose. Bleeding events were comparable.

ClinicalTrials.gov ID

NCT04235569, 22 January 2020.

Evaluation of an Initiation Regimen of Warfarin for International Normalized Ratio Target 2.0 to 3.0

Background: he number of patients on warfarin therapy is rising steadily. Although warfarin is beneficial, it carries a high risk of bleeding, especially if the international normalized ratio (INR) values exceed 3.0. Currently, no warfarin initiation regimens have been developed for the Asian population, especially for Malaysians. Objective: This article describes the efficacy and safety of a new initiation regimen for warfarin among warfarin-naive patients. Method: Data were retrospectively collected from the ambulatory and inpatient settings. Results: A total of 165 patients who each had a target INR of 2.0 to 3.0 were included in the study. The mean age was 57.2 years and 94 patients were male. A total of 108 patients used Regimen 1 (5 mg/5 mg/3mg) and the rest of the patients used Regimen 2 (5 mg/3 mg/3 mg). Most patients used warfarin either for atrial fibrillation (52.1%) or for venous thromboembolism (29.7%). Overall, 88 of the patients had INR values above 50% from the baseline on Day 4. Additionally, 13 patients had INR values of >3.2, which required withholding and lower dose of warfarin. The predicted weekly maintenance warfarin dose (23 ± 0.5 mg/week) was found to have correlated closely with the actual maintenance dose (22.8 ± 0.5 mg/week; r ² = 0.75). Nearly two thirds (70.3%) of the patients achieved the target INR on Day 11. Conclusion: The warfarin initiation regimens in this study was simple, safe, and suitable to be used in both ambulatory and inpatient settings for managing warfarin therapy.

Anticoagulation Type and Early Recurrence in Cardioembolic Stroke: The IAC Study

BACKGROUND AND PURPOSE

In patients with acute ischemic stroke and atrial fibrillation, treatment with low molecular weight heparin increases early hemorrhagic risk without reducing early recurrence, and there is limited data comparing warfarin to direct oral anticoagulant (DOAC) therapy. We aim to compare the effects of the treatments above on the risk of 90-day recurrent ischemic events and delayed symptomatic intracranial hemorrhage.

METHODS

We included consecutive patients with acute ischemic stroke and atrial fibrillation from the IAC (Initiation of Anticoagulation after Cardioembolic) stroke study pooling data from stroke registries of 8 comprehensive stroke centers across the United States. We compared recurrent ischemic events and delayed symptomatic intracranial hemorrhage between each of the following groups in separate Cox-regression analyses: (1) DOAC versus warfarin and (2) bridging with heparin/low molecular weight heparin versus no bridging, adjusting for pertinent confounders to test these associations.

RESULTS

We identified 1289 patients who met the bridging versus no bridging analysis inclusion criteria and 1251 patients who met the DOAC versus warfarin analysis inclusion criteria. In adjusted Cox-regression models, bridging (versus no bridging) treatment was associated with a high risk of delayed symptomatic intracranial hemorrhage (hazard ratio, 2.74 [95% CI, 1.01-7.42]) but a similar rate of recurrent ischemic events (hazard ratio, 1.23 [95% CI, 0.63-2.40]). Furthermore, DOAC (versus warfarin) treatment was associated with a lower risk of recurrent ischemic events (hazard ratio, 0.51 [95% CI, 0.29-0.87]) but not delayed symptomatic intracranial hemorrhage (hazard ratio, 0.57 [95% CI, 0.22-1.48]).

CONCLUSIONS

Our study suggests that patients with ischemic stroke and atrial fibrillation would benefit from the initiation of a DOAC without bridging therapy. Due to our study limitations, these findings should be interpreted with caution pending confirmation from large prospective studies.

The Use of Rivaroxaban for Unprovoked Pulmonary Embolism in the Setting of Antithrombin Deficiency

A 24-year-old woman with antithrombin (AT) deficiency presented with right-sided pleuritic chest pain of five days duration with diagnosis of pulmonary embolism (PE) made at an outside hospital. After discussion of treatment options with the patient, her treatment was changed to rivaroxaban protocol. The case illustrates an appropriate treatment plan for patients with AT deficiency presenting with unprovoked PE, especially when prioritizing ease of use.

Assessment of warfarin algorithms for hospitalized adults: searching for a safe dosing strategy

This study evaluates three warfarin dosing algorithms (Kimmel, Dawson, High Dose ≥ 2.5 mg) for hospitalized older adults. A random selection of 250 patients with overshoots (INR ≥ 5 after 48 h of hospitalization) and 250 patients without overshoots were accessed from a database of 12,107 inpatients ≥ 65 years treated with chronic warfarin during hospitalization between January 1, 2014 and June 30, 2016. Algorithms were retrospectively applied to patients 2 days prior to overshoots in the overshoot group, and 2 days prior to the maximum INR reached after 48 h of hospitalization in the non-overshoot group. Patients were categorized as overdosed or not overdosed and compared using descriptive statistics. Logistic regression modeling determined predictors for overshoots. There was no significant difference between overdose and non-overdose groups for progressing to overshoots by the Kimmel (51.0% vs. 48.7%, p = 0.67) or Dawson (48.5 vs. 57.9%, p = 0.19) algorithms. The Low Dose Group (≤ 2.5 mg) was significantly more likely to experience an overshoot than the High Dose Group (56.6% vs. 45.5%, p = 0.04). The Low Dose Group was more likely to be older (81.4% vs. 71.1%, p = 0.02), female (63.5% vs. 49.8%, p = 0.02), weigh less (71.3 ± 21.9 vs. 79 ± 23.1, p = 0.002), and be prescribed amiodarone (16.6% vs. 8.1%, p = 0.01). While none of the algorithms predicted overshoots in logistic regression modeling, weight over 70 kg and black race remained protective. The High Dose Algorithm revealed that providers appropriately gave lower doses to patients at highest risk for warfarin sensitivity. Future studies are needed to investigate tools for inpatient warfarin dosing in older adults.

Preliminary outcomes of preemptive warfarin pharmacogenetic testing at a large rural healthcare center

PURPOSE

As a preliminary evaluation of the outcomes of implementing pharmacogenetic testing within a large rural healthcare system, patients who received pre-emptive pharmacogenetic testing and warfarin dosing were monitored until June 2017.

SUMMARY

Over a 20-month period, 749 patients were genotyped for VKORC1 and CYP2C9 as part of the electronic Medical Records and Genomics Pharmacogenetics (eMERGE PGx) study. Of these, 27 were prescribed warfarin and received an alert for pharmacogenetic testing pertinent to warfarin; 20 patients achieved their target international normalized ratio (INR) of 2.0-3.0, and 65% of these patients achieved target dosing within the recommended pharmacogenetic alert dose (± 0.5 mg/day). Of these, 10 patients had never been on warfarin prior to the alert and were further evaluated with regard to time to first stable target INR, bleeds and thromboembolic events, hospitalizations, and mortality. There was a general trend of faster time to first stable target INR when the patient was initiated at a warfarin dose within the alert recommendation versus a dose outside of the alert recommendation with a mean (± SD) of 34 (± 28) days versus 129 (± 117) days, respectively. No trends regarding bleeds, thromboembolic events, hospitalization, or mortality were identified with respect to the pharmacogenetic alert. The pharmacogenetic alert provided pharmacogenetic dosing information to prescribing clinicians and appeared to deploy appropriately with the correct recommendation based upon patient genotype.

CONCLUSION

Implementing pharmacogenetic testing as a standard of care service in anticoagulation monitoring programs may improve dosage regimens for patients on anticoagulation therapy.

Comparison of 10-mg and 5-mg warfarin initiation nomograms in a South Indian population - An open label trial

INTRODUCTION

Early achievement of therapeutic INR leads to shorter hospital stay and lesser cost. Two warfarin initiation nomograms (10 mg nomogram and 5 mg nomogram) are widely used but it is not yet clear which one is better. They have been validated in the West but there are no studies from India. We undertook this study to compare the efficacy and safety of the 10 mg and 5 mg nomograms in the Indian population.

METHODS

169 patients were enrolled between august 2014 to July 2016. Patients with venous thromboembolism or atrial fibrillation secondary to valvular heart disease were included. Patients were allocated to 10 mg or 5 mg nomogram as per the policy of the treating unit.

RESULTS

52% of patients in the 10 mg nomogram achieved therapeutic INR by day 5 as compared to only 17% in the 5 mg nomogram (P = 0.022). The median time to achieve therapeutic INR was much shorter in the 10 mg nomogram (5 days vs 14 days, p = 0.018). Two patients in the 10 mg group (2.3%) and none in the 5 mg group had INR > 4 but they did not have any bleeding.

CONCLUSION

The 10 mg nomogram achieved therapeutic INR significantly earlier with less INR measurements and appears safe. Indian patients require higher a dose of warfarin at initiation and maintenance as compared to other ethnic groups.

Follow-up and management of valvular heart disease patients with prosthetic valve: a clinical practice guideline for Indian scenario

PURPOSE

Valvular heart disease (VHD) patients after prosthetic valve implantation are at risk of thromboembolic events. Follow-up care of patients with prosthetic valve has a paramount role in reducing the morbidity and mortality. Currently, in India, there is quintessential need to stream line the follow-up care of prosthetic valve patients. This mandates the development of a consensus guideline for the antithrombotic therapy in VHD patients post prosthetic valve implantation.

METHODS

A national level panel was constituted comprising 13 leading cardio care experts in India who thoroughly reviewed the up to date literature, formulated the recommendations, and developed the consensus document. Later on, extensive discussions were held on this draft and the recommendations in 8 regional meetings involving 79 additional experts from the cardio care in India, to arrive at a consensus. The final consensus document is developed relying on the available evidence and/or majority consensus from all the meetings.

RESULTS

The panel recommended vitamin K antagonist (VKA) therapy with individualized target international normalized ratio (INR) in VHD patients after prosthetic valve implantation. The panel opined that management of prosthetic valve complications should be personalized on the basis of type of complications. In addition, the panel recommends to distinguish individuals with various co-morbidities and attend them appropriately.

CONCLUSIONS

Anticoagulant therapy with VKA seems to be an effective option post prosthetic valve implantation in VHD patients. However, the role for non-VKA oral therapy in prosthetic valve patients and the safety and efficacy of novel oral anticoagulants in patients with bioprosthetic valve need to be studied extensively.

Optimizing quality care for the oral vitamin K antagonists (VKAs)

Vitamin K antagonists (VKAs) have been the only oral anticoagulants for decades. The management of anticoagulant therapy with VKA is challenging because of the intricate pharmacological properties of these agents. The success of VKA therapy depends on the quality of treatment that is ensured through continuing comprehensive communication and education. The educational program should address important issues of the VKA therapy such as beginning of treatment, pharmacological, dietary, and drug-drug interactions, as well as treatment temporary suspension during surgical interventions or invasive maneuvers. In addition, the initial and continuing patient education is of imperative importance. A major role in the educational process may be addressed by patient associations. The quality of treatment is better reached if patients are followed in anticoagulation clinics. Moreover, a federation of anticoagulation clinics may improve patient care through regular meetings to update knowledge on VKA treatment. Learning objectives of this paper is to allow readers to correctly approach patients starting VKA treatment, recognize possible pitfalls of treatment, and provide adequate solutions.

The impact of R353Q genetic polymorphism in coagulation factor VII on the initial anticoagulant effect exerted by warfarin

BACKGROUND

The initial rise in INR following warfarin is attributed to rapid decline in coagulation factor VII (F7). The R353Q polymorphism in F7 accounts for approximately 1/3 of the variability in F7 activity (FVIIc).

OBJECTIVE

Evaluate the role of R353Q in the initial response to warfarin.

METHODS

Twenty-eight healthy, males, carrying CYP2C9*1/*1 (n = 14), CYP2C9*1/*2 (n = 4) or CYP2C9*1/*3 (n = 10) genotypes, received single 20 mg warfarin. S&R-warfarin concentrations, INR, and FVIIc were monitored periodically for 7 days.

RESULTS

Baseline and maximal INR were 5.6% and 33.5% higher among carriers of the RQ (n = 12) as compared with those carrying the RR (n = 16) genotype (p = 0.032, p = 0.003, respectively). Baseline and nadir FVIIc were 21.6% and 42.0% lower among subjects carrying the RQ as compared with carriers of the RR genotype (p = 0.001, p = 0.007 respectively). In multiple regression analysis, R353Q predicted 36.6% of the variability in peak INR whereas 20.2%, 9.9%, and 5.9% were attributed to VKORC1 genetic polymorphism, cholesterol concentration, and S Warfarin concentration after 24 h, respectively.

CONCLUSIONS

R353Q genetic polymorphism plays a key role in determining the initial response to warfarin. The incorporation of this genetic variant into warfarin loading algorithm should be further investigated.

Cardiovascular Pharmacogenomics: Does It Matter If You're Black or White?

Race and ancestry have long been associated with differential risk and outcomes to disease as well as responses to medications. These differences in drug response are multifactorial with some portion associated with genomic variation. The field of pharmacogenomics aims to predict drug response in patients prior to medication administration and to uncover the biological underpinnings of drug response. The field of human genetics has long recognized that genetic variation differs in frequency between ancestral populations, with some single nucleotide polymorphisms found solely in one population. Thus far, most pharmacogenomic studies have focused on individuals of European and East Asian ancestry, resulting in a substantial disparity in the clinical utility of genetic prediction for drug response in US minority populations. In this review, we discuss the genetic factors that underlie variability to drug response and known pharmacogenomic associations and how these differ between populations, with an emphasis on the current knowledge in cardiovascular pharmacogenomics.

Early Response to Warfarin Initiation and the Risk of Venous Thromboembolism After Total Joint Arthroplasty

BACKGROUND

Venous thromboembolism chemoprophylaxis with warfarin is common after total joint arthroplasty. Early response to warfarin initiation has been theorized to engender a transient increase in the risk of venous thromboembolism. We hypothesized that a rapid rise in the international normalized ratio is a risk factor for venous thromboembolism after total joint arthroplasty.

METHODS

This study was a retrospective analysis of Medicare patients undergoing elective total joint arthroplasty who were given nomogram-dosed warfarin for venous thromboembolism prophylaxis. Logistic regression was used to assess the relationship between the postoperative rate of change in the international normalized ratio and the occurrence of symptomatic venous thromboembolism within 30 days postoperatively.

RESULTS

The study included 948 patients (715 total knee arthroplasty, 233 total hip arthroplasty), of whom 4.4% experienced symptomatic venous thromboembolism within 30 days postoperatively. The change in the international normalized ratio from postoperative day 1 to postoperative day 2 was significantly greater in the symptomatic venous thromboembolism group compared with the group that did not have venous thromboembolism (increase of 0.70 versus 0.46; P = 0.008). Regression analysis showed that a higher rate of change in the international normalized ratio was associated with increased risk of symptomatic venous thromboembolism (odds ratio, 2.59 per unit of change in the international normalized ratio; 95% confidence interval, 1.51-4.38; P = 0.001).

CONCLUSION

A rapid rise in the international normalized ratio after warfarin initiation in total joint arthroplasty patients is associated with increased risk of symptomatic venous thromboembolism. This novel finding identifies a population at risk for this complication. Further study of the early effects of warfarin therapy is warranted.

LEVEL OF EVIDENCE

Level III.

Impact of INR monitoring, reversal agent use, heparin bridging, and anticoagulant interruption on rebleeding and thromboembolism in acute gastrointestinal bleeding

Background

Anticoagulant management of acute gastrointestinal bleeding (GIB) during the pre-endoscopic period has not been fully addressed in American, European, or Asian guidelines. This study sought to evaluate the risks of rebleeding and thromboembolism in anticoagulated patients with acute GIB.

Methods

Baseline, endoscopy, and outcome data were reviewed for 314 patients with acute GIB: 157 anticoagulant users and 157 age-, sex-, and important risk-matched non-users. Data were also compared between direct oral anticoagulants (DOACs) and warfarin users.

Results

Between anticoagulant users and non-users, of whom 70% underwent early endoscopy, no endoscopy-related adverse events or significant differences were found in the rate of endoscopic therapy need, transfusion need, rebleeding, or thromboembolism. Rebleeding was associated with shock, comorbidities, low platelet count and albumin level, and low-dose aspirin use but not HAS-BLED score, any endoscopic results, heparin bridge, or international normalized ratio (INR) ≥ 2.5. Risks for thromboembolism were INR ≥ 2.5, difference in onset and pre-endoscopic INR, reversal agent use, and anticoagulant interruption but not CHA2DS2-VASc score, any endoscopic results, or heparin bridge. In patients without reversal agent use, heparin bridge, or anticoagulant interruption, there was only one rebleeding event and no thromboembolic events. Warfarin users had a significantly higher transfusion need than DOACs users.

Conclusion

Endoscopy appears to be safe for anticoagulant users with acute GIB compared with non-users. Patient background factors were associated with rebleeding, whereas anticoagulant management factors (e.g. INR correction, reversal agent use, and drug interruption) were associated with thromboembolism. Early intervention without reversal agent use, heparin bridge, or anticoagulant interruption may be warranted for acute GIB.

Time to achieving therapeutic international normalized ratio increases hospital length of stay after heart valve replacement surgery

BACKGROUND

Achieving a therapeutic international normalized ratio (INR) before hospital discharge is an important inpatient goal for patients undergoing mechanical cardiac valve replacement (MCVR). The use of clinical algorithms has reduced the time to achieve therapeutic INR (TTI) with warfarin therapy. Whether TTI prolongs length of stay (LOS) is unknown.

METHODS

Patients who underwent MCVR over a consecutive 42-month period were included. Clinical data were obtained from the Society of Thoracic Surgeons Adult Cardiac Surgery database and electronic medical records. Therapeutic INR was defined as per standard guidelines. Warfarin dose was prescribed using an inpatient pharmacy-managed algorithm and computer-based dosing tool. International normalized ratio trajectory, procedural needs, and drug interactions were included in warfarin dose determination.

RESULTS

There were 708 patients who underwent MCVR, of which 159 were excluded for reasons that would preclude or interrupt warfarin use. Among the remainder of 549 patients, the average LOS was 6.4days and mean TTI was 3.5days. Landmark analysis showed that subjects in hospital on day 4 (n=542) who achieved therapeutic INR were more likely to be discharged by day 6 compared with those who did not achieve therapeutic INR (75% vs 59%, P<.001). Multivariable proportional hazards regression with TTI as a time-dependent effect showed a strong association with discharge (P=.0096, hazard ratio1.3) after adjustment for other significant clinical covariates.

CONCLUSIONS

Time to achieve therapeutic INR is an independent predictor of LOS in patients requiring anticoagulation with warfarin after MCVR surgery. Alternative dosing and anticoagulation strategies will need to be adopted to reduce LOS in these patients.

Implications of an inpatient warfarin dosing nomogram on safety outcomes post-discharge

Many hospitals have implemented warfarin dosing nomograms to improve patient safety. To our knowledge, no study has assessed the impact inpatient warfarin initiation has in both medical and surgical patients, on safety outcomes post discharge. To evaluate the impact of a suggested institutional nomogram for the initiation of warfarin, the primary endpoint was the incidence of bleeding throughout follow up. Secondary endpoints included the composite of INR changes ≥0.5/day and INR >4. Patients were followed for a period of 2 weeks post-discharge. The composite endpoint was evaluated for an effect on reaching therapeutic INR, time to reach therapeutic INR, and bleeding events throughout follow up. A single center retrospective study comparing the safety of adherence vs. non-adherence to a warfarin nomogram. A total of 206 patients were included, 73 patients in the nomogram adherence vs. 133 in the nonadherence arm. There was no difference in the proportion of patients who bled throughout the follow up period, adherence 9.6% vs. nonadherence to the nomogram 13.5%, p = 0.407. There was however a statistical difference in the mean total number of bleeding events, 0.096 (7/73) in the adherence vs. 0.158 (21/133) in the non-adherence arm, p = 0.022. There was also no difference in the composite endpoint, 19.2% in the adherence vs. 28.6% in the non-adherence arm p = 0.180. A positive correlation between the inpatient composite and risk of bleeding throughout follow up was noted. The findings of this study support adherence to the nomogram as opposed to non-adherence.

During warfarin induction, the Fiix-prothrombin time reflects the anticoagulation level better than the standard prothrombin time

Essentials Fiix-prothrombin time (PT) monitoring of warfarin measuring factor (F) II and X, is effective. Plasma obtained during warfarin induction and stable phase in Fiix-trial was assayed. Fiix-PT stabilized anticoagulation earlier than monitoring with traditional PT-INR. FVII had little effect on thrombin generation that was mainly determined by FII and FX.

SUMMARY

Background The prothrombin time (PT) is equally prolonged by reduction of each of the vitamin K-dependent (VKD) factors (F) II, VII and X. The Fiix-PT is only affected by FII and FX, the main contributors to thrombin generation (TG). Objective To test the hypothesis that variability in warfarin anticoagulation is reduced early during monitoring with the normalized PT-ratio calculated from Fiix-PT (Fiix-International Normalized Ratio [INR]) compared with traditional PT-INR monitoring. Also, that because of its insensitivity to FVII, Fiix-PT more accurately reflects TG when Fiix-INR and PT-INR are discrepant. Methods Samples from Fiix-trial participants monitored with either Fiix-PT or PT were used. VKD coagulation factors and TG were measured in samples from 40 patients during stable anticoagulation and in serial samples obtained from 26 patients during warfarin induction. TG was assessed in relation to selective reduction in single VKD factors. Results During Fiix-warfarin induction full anticoagulation measured as FII or FX activity was achieved at a similar rate to that with PT-warfarin but subsequently stabilized better. Fiix-INR but not PT-INR mirrored total TG during initiation. During induction, FII (R2 = 0.66) and FX (R2 = 0.52) correlated better with TG and with a steeper slope than did FIX (R2 = 0.37) and in particular FVII (R2 = 0.21). In vitro, FII and FX were the main determinants of TG at concentrations observed during VKA anticoagulation, whereas FVII and FIX had little influence. Conclusions Fiix-PT monitoring reduces anticoagulation variability, suggesting that monitoring FVII has a limited role during VKA management. TG is better reflected by Fiix-PT.

Antiplatelet and antithrombotic effects of cordycepin-enriched WIB-801CE from Cordyceps militaris ex vivo, in vivo, and in vitro

BACKGROUND

A species of the fungal genus Cordyceps has been used as a complementary and alternative medicine of traditional Chinese medicine, and its major component cordycepin and cordycepin-enriched WIB-801CE are known to have antiplatelet effects in vitro. However, it is unknown whether they have also endogenous antiplatelet and antithrombotic effects. In this study, to resolve these doubts, we prepared cordycepin-enriched WIB-801CE, an ethanol extract from Cordyceps militaris-hypha, then evaluated its ex vivo, in vivo, and in vitro antiplatelet and antithrombotic effects.

METHODS

Ex vivo effects of WIB-801CE on collagen- and ADP-induced platelet aggregation, serotonin release, thromboxane A2 (TXA2) production and its associated activities of enzymes [cyclooxygenase-1 (COX-1), TXA2 synthase (TXAS)], arachidonic acid (AA) release and its associated phosphorylation of phospholipase Cβ3, phospholipase Cγ2 or cytosolic phospholipase A2, mitogen-activated protein kinase (MAPK) [p38 MAPK, extracellular signal-regulated kinase (ERK)], and blood coagulation time in rats were investigated. In vivo effects of WIB-801CE on collagen plus epinephrine-induced acute pulmonary thromboembolism, and tail bleeding time in mice were also inquired. In vitro effects of WIB-801CE on cytotoxicity, and fibrin clot retraction in human platelets, and nitric oxide (NO) production in RAW264.7 cells or free radical scavenging activity were studied.

RESULTS

Cordycepin-enriched WIB-801CE inhibited ex vivo platelet aggregation, TXA2 production, AA release, TXAS activity, serotonin release, and p38 MAPK and ERK2 phosphorylation in collagen- and ADP-activated rat platelets without affecting blood coagulation. Furthermore, WIB-801CE manifested in vivo inhibitory effect on collagen plus epinephrine-induced pulmonary thromboembolism mice model. WIB-801CE inhibited in vitro NO production and fibrin clot retraction, but elevated free radical scavenging activity without affecting cytotoxicity against human platelets.

CONCLUSION

WIB-801CE inhibited collagen- and ADP-induced platelet activation and its associated thrombus formation ex vivo and in vivo. These were resulted from down-regulation of TXA2 production and its related AA release and TXAS activity, and p38MAPK and ERK2 activation. These results suggest that WIB-801CE has therapeutic potential to treat platelet activation-mediated thrombotic diseases in vivo.

Short-Term Risk of Bleeding During Heparin Bridging at Initiation of Vitamin K Antagonist Therapy in More Than 90 000 Patients With Nonvalvular Atrial Fibrillation Managed in Outpatient Care

Background

Several studies have recently examined the risks of bleeding and of ischemic stroke and systemic embolism associated with perioperative heparin bridging anticoagulation in patients with nonvalvular atrial fibrillation. However, few studies have investigated bridging risks during vitamin K antagonist initiation in outpatient settings.

Methods and Results

A retrospective cohort study was conducted on individuals starting oral anticoagulation between January 2010 and November 2014 for nonvalvular atrial fibrillation managed in outpatient care and identified from French healthcare insurance. Bleeding and ischemic stroke and systemic embolism events were identified from the hospitalization database. Adjusted hazard ratios with 95% CI were estimated using Cox models during the first and 2 following months of anticoagulation. Of 90 826 individuals, 30% had bridging therapy. A total of 318 (0.35%) cases of bleeding and 151 (0.17%) ischemic stroke and systemic embolism cases were identified during the first month of follow‐up and 231 (0.31%) and 122 (0.16%) during the 2 following months, respectively. At 1 month of follow‐up, the incidence of bleeding was higher in the bridged group compared with the nonbridged group (0.47% versus 0.30%; P<0.001), and this increased risk persisted after adjustment for covariates (hazard ratio=1.60; 95% CI, 1.28–2.01). This difference disappeared after the first month of treatment (0.93; 0.70–1.23). No significant difference in the occurrence of ischemic stroke and systemic embolism was observed either at 1 month of follow‐up or later.

Conclusions

At vitamin K antagonist initiation for nonvalvular atrial fibrillation managed in ambulatory settings, bridging therapy is associated with a higher risk of bleeding and a similar risk of arterial thromboembolism compared with no bridging therapy.

Comparing Usual Care With a Warfarin Initiation Protocol After Mechanical Heart Valve Replacement

BACKGROUND

The immediate postoperative warfarin sensitivity for patients receiving heart valve prostheses is increased. Established warfarin initiation protocols may lack clinical applicability, resulting in dosing based on clinical judgment.

OBJECTIVE

To compare current practice for warfarin initiation with a known warfarin initiation protocol, with doses proportionally reduced to account for the increased postoperative sensitivity.

METHODS

We compared the Mechanical Heart Valve Warfarin Initiation Protocol (Protocol group) with current practice (clinical judgment-Empirical group) for patients receiving mechanical heart valves in an observational before-and-after format. End points were the time to achieve a stable therapeutic international normalized ratio (INR), doses held in the first 6 days, and overanticoagulation in the first 6 days.

RESULTS

The Protocol group (n = 37) achieved a stable INR more rapidly than the Empirical group (n = 77; median times 5.1 and 8.7 days, respectively; P = 0.002). Multivariable analysis indicated that the Protocol group (hazard ratio [HR] = 2.22; P = 0.005) and men (HR = 1.76; P = 0.043) more rapidly achieved a stable therapeutic INR. Age, serum albumin, amiodarone, presence of severe heart failure, and surgery type had no impact. Protocol patients had fewer doses held (1.1% vs 10.1%, P < 0.001) and no difference in overanticoagulation (2.7% vs 9.1%, P = 0.27).

CONCLUSION

The Mechanical Heart Valve Warfarin Initiation Protocol provided a reliable approach to initiating warfarin in patients receiving mechanical aortic or mitral valves.

Anticoagulation in the Elderly

Oral anticoagulation has been shown to provide great benefit in preventing and treating thromboembolic disorders. The challenges of oral anticoagulation management in the elderly involve balancing the risks of bleeding versus the benefits of a life-saving treatment. Due to the complex nature of warfarin, therapy must be individualized with frequent monitoring, re-education, and adjustments based on concurrent illness and drug therapy. This review focuses on the use of warfarin, including indications, dosing recommendations, drug and dietary interactions, and reversal of anticoagulation. Methods to determine bleeding risks in this population and barriers that interfere with the prescribing of warfarin are discussed. Strategies to improve patient outcome and reduce adverse events are provided to assist clinicians in their decision-making skills. The potential advantages of anticoagulation clinics are summarized with regards to coordinating the care and minimizing the risks of anticoagulant therapy. The role of new-generation anticoagulants is also discussed as to their place in therapy.

Warfarin Dosing and Time Required to Reach Therapeutic International Normalized Ratio in Patients with Hypercoagulable Conditions

Objective:

The purpose of this study was to analyze the difference in duration of anticoagulation and dose of warfarin required to reach a therapeutic international normalized ratio [(INR) of 2 to 3] in patients with hypercoagulable conditions as compared to controls. To our knowledge, this study is the first in the literature to delineate such a difference.

Materials and Methods:

A retrospective chart review was performed in a tertiary care hospital. The total study population was 622. Cases (n=125) were patients with a diagnosis of a hypercoagulable syndrome who developed venous thromboembolism. Controls (n=497) were patients with a diagnosis of venous thromboembolism in the absence of a hypercoagulable syndrome and were matched for age, sex, and race.

Results:

The total dose of warfarin required to reach therapeutic INR in cases was higher (50.7±17.6 mg) as compared to controls (41.2±17.7 mg). The total number of days required to reach therapeutic INR in cases was 8.9±3.5 days as compared to controls (6.8±2.9 days). Both of these differences were statistically significant (p<0.001).

Conclusion:

Patients with hypercoagulable conditions require approximately 10 mg of additional total warfarin dose and also require, on average, 2 extra days to reach therapeutic INR as compared to controls.

Warfarin initiation nomograms for venous thromboembolism

BACKGROUND

Venous thromboembolism (VTE) is a common condition in hospital patients. Considerable controversy is ongoing regarding optimal initial warfarin dosing for patients with acute deep venous thrombosis (DVT) and pulmonary embolism (PE). Achieving a therapeutic international normalized ratio (INR) with warfarin as soon as possible is important because this minimizes the duration of parenteral medication necessary to attain immediate anticoagulation, and it potentially decreases the cost and inconvenience of treatment. Although a 5-mg loading-dose nomogram tends to prevent excessive anticoagulation, a 10-mg loading-dose nomogram may achieve a therapeutic INR more quickly. This is an update of a review first published in 2013.

OBJECTIVES

To evaluate the efficacy of a 10-mg warfarin nomogram compared with a 5-mg warfarin nomogram among patients with VTE.

SEARCH METHODS

For this update the Cochrane Vascular Trials Search Co-ordinator searched the Specialised Register (last searched September 2015) and the Cochrane Register of Studies (CENTRAL (2015, Issue 8). Clinical trials databases were also searched. The review authors searched PubMed (last searched 11 June 2015) and LILACS (last searched 11 June 2015). In addition, the review authors contacted pharmaceutical companies.

SELECTION CRITERIA

Randomized controlled studies comparing warfarin initiation nomograms of 10 and 5 mg in patients with VTE.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. The review authors contacted study authors for additional information.

MAIN RESULTS

Four trials involving 494 participants were included. Three studies involving 383 participants provided data on the proportion of participants who had achieved a therapeutic INR by day five. Significant benefit of a 10-mg warfarin nomogram was observed (risk ratio (RR) 1.27, 95% confidence interval (CI) 1.05 to 1.54; moderate quality evidence), although with substantial heterogeneity (I(2) = 90%). The review authors analyzed each study separately because it was not possible to perform a subgroup analysis by inpatient or outpatient status. One study showed significant benefit of a 10-mg warfarin nomogram for the proportion of outpatients with VTE who had achieved a therapeutic INR by day five (RR 1.78, 95% CI 1.41 to 2.25), with the number needed to treat for an additional beneficial outcome (NNTB = 3, 95% CI 2 to 4); another study showed significant benefit of a 5-mg warfarin nomogram in outpatients with VTE (RR 0.58, 95% CI 0.36 to 0.93) with NNTB = 5 (95% CI 3 to 28); a third study, consisting of both inpatients and outpatients, showed no difference (RR 1.08, 95% CI 0.65 to 1.80).No difference was observed in recurrent venous thromboembolism at 90 days when the warfarin nomogram of 10 mg was compared with the warfarin nomogram of 5 mg (RR 1.48, 95% CI 0.39 to 5.56; 3 studies, 362 participants, low quality evidence); no difference was observed in major bleeding at 14 to 90 days (RR 0.97, 95% CI 0.27 to 3.51; 4 studies, 494 participants, moderate quality evidence). No difference was observed in minor bleeding at 14 to 90 days (RR 0.52, 95% CI 0.15 to 1.83; 2 studies, 243 participants, very low quality evidence) or in length of hospital stay (mean difference (MD) -2.3 days, 95% CI -7.96 to 3.36; 1 study, 111 participants, low quality evidence).

AUTHORS' CONCLUSIONS

In patients with acute thromboembolism (DVT or PE) aged 18 years or older, considerable uncertainty surrounds the use of a 10-mg or a 5-mg loading dose for initiation of warfarin to achieve an INR of 2.0 to 3.0 on the fifth day of therapy. Heterogeneity among analyzed studies, mainly caused by differences in types of study participants and length of follow-up, limits certainty surrounding optimal warfarin initiation nomograms.

The Efficacy and Safety of Oral Rivaroxaban in Patients with Non-Valvular Atrial Fibrillation Scheduled for Electrical Cardioversion

Objective Electrical cardioversion (EC) is associated with an increased risk of thrombotic events in patients with non-valvular atrial fibrillation (NVAF). Patients who experience AF for a period of >48 hours therefore require adequate anticoagulation therapy for at least 3 weeks before and 4 weeks after EC. While the guidelines address the management of vitamin K antagonists (VKAs), there are limited data on the use of novel oral anticoagulants (NOAC). One NOAC, rivaroxaban, has a rapid onset of action and might therefore shorten the time for which anti-coagulant treatment is required before a patient undergoes EC. Methods This study included 91 patients with NVAF of >48 hours in duration or in whom the time of onset was unknown who were undergoing EC after pretreatment with rivaroxaban. All of the patients were pretreated with rivaroxaban for at least 2 hours before EC and the same dose of rivaroxaban was prescribed for 4 weeks after EC. The primary endpoint was a successful EC without any thrombotic events or bleeding complications within 30 days after EC. The secondary endpoint was the time to EC. Results The mean age was 63±12 years and 70 of the 91 patients were male. The CHADS2 and HAS-BLED scores were 1.0±1.0 and 1.7±1.3, respectively. Although there were no thrombotic events, minor bleeding (gingival hemorrhage) occurred 20 days after the initiation of rivaroxaban treatment in one patient. The average time to EC was 11.9±11.1 days. Conclusion Rivaroxaban is safe and effective drug for NVAF patients who are scheduled for an EC. Furthermore, since VKAs take a substantial amount of time to establish adequate anticoagulation, pretreatment with rivaroxaban could shorten the time to the EC.

Factors influencing warfarin response in hospitalized patients

The objective of this study was to investigate the influence of simultaneous factors that potentially keep patients far from achieving target INR range at discharge in hospitalized patients. Prospective cross-sectional observational study conducted at the Cardiology Department and Intensive Care Unit (ICU) of the Assiut University Hospitals. One-hundred and twenty patients were enrolled in the study from July 2013 to January 2014. Outcome measures were discharge INRs, bleeding and thromboembolic episodes. Bivariate analysis and multinomial logistic regression were conducted to determine independent risk factors that can keep patients outside target INR range.

Patients who were newly initiated warfarin on hospital admission were given low initiation dose (2.8 mg ± 0.9). They were more likely to have INR values below 1.5 during hospital stay, 13 (27.7%) patients compared with 9 (12.3%) previously treated patients, respectively (p = .034). We found that the best predictors of achieving below target INR range relative to within target INR range were; shorter hospital stay periods (OR, 0.82 for every day increase [95% CI, 0.72–0.94]), being a male patient (OR, 2.86 [95% CI, 1.05–7.69]), concurrent infection (OR, 0.21 [95% CI, 0.07–0.59]) and new initiation of warfarin therapy on hospital admission (OR, 3.73 [95% CI, 1.28–10.9]).

Gender, new initiation of warfarin therapy on hospital admission, shorter hospital stay periods and concurrent infection can have a significant effect on discharge INRs. Initiation of warfarin without giving loading doses increases the risk of having INRs below 1.5 during hospital stay and increases the likelihood of a patient to be discharged with INR below target range. Following warfarin dosing nomograms and careful monitoring of the effect of various factors on warfarin response should be greatly considered.

Rationale and Design of Triple AXEL: Trial for Early Anticoagulation in Acute Ischemic Stroke Patients with Nonvalvular Atrial Fibrillation

Rationale

Patients with atrial fibrillation (AF) in the acute stage of ischemic stroke or transient ischemic attack (TIA) are at high risk of recurrent stroke, but the optimal anticoagulation strategy remains unclear due to the concern of intracranial bleeding. Novel oral anticoagulants compared to warfarin might be more safe and efficacious in patients suitable for early anticoagulation.

Aims

This trial is to evaluate the feasibility of early anticoagulation with rivaroxaban in acute ischemic stroke or TIA patients with nonvalvular AF.

Design

This is a randomized, open-label, blinded endpoint evaluation trial. Inclusion criteria are ( 1 ) nonvalvular AF, ( 2 ) presumed cardioembolic stroke or transient ischemic attack (TIA) confirmed by MRI within five-days from onset, and ( 3 ) mild to moderate stroke severity. We will randomize 196 patients to either rivaroxaban (10 mg once daily for five-days followed by 15 mg or 20 mg once daily) or dose-adjusted warfarin (coadministration of aspirin 100 mg per day until achieving international normalized ratio of 1·7). The study is registered in ClinicalTrials.gov (NCT02042534).

Study outcomes

The primary endpoint is the composite of recurrent ischemic lesion and intracranial bleeding on MRI at four-weeks. Secondary endpoints are recurrent ischemic lesions, intracranial bleeding, major bleeding, major vascular events, four-week modified Rankin Scale score, and duration of hospitalization after randomization.

Discussion

The results of this proof-of-concept trial will guide go/no-go decision to a large phase 3 confirmatory trial.

Loading dose vs. maintenance dose of warfarin for reinitiation after invasive procedures: a randomized trial

BACKGROUND

There is uncertainty regarding the optimal dosing regimen for the resumption of warfarin after interruption for invasive procedures.

AIM

To determine the efficacy and safety of warfarin resumption with loading doses or with the most recent maintenance dose.

METHODS

Patients receiving warfarin treatment and planned for invasive procedures with an expected hospital stay of ≤ 1 day were randomized to resume warfarin on the day of the procedure, defined as day 1, with most recent maintenance dose or with 2 initial days of double maintenance dose. Efficacy outcomes were proportion of international normalized ratio (INR) levels ≥ 2.0 on day 5 (primary outcome) and day 10. Safety outcomes were bleeding and thromboembolic events. In addition, D-dimer levels were analyzed on days 5 and 10 in a subset of the population.

RESULTS

There were 49 patients analyzed in each group. INR of ≥ 2.0 had been achieved by day 5 for 13% in the maintenance-dose group and for 50% in the loading-dose group (relative risk [RR] 0.27, 95% confidence interval [CI] 0.10-0.60) and by day 10 for 68% and 87%, respectively (RR 0.78, 95% CI 0.65-1.00). There were no thromboembolic events, and there was one major bleed before resumption of warfarin and one minor bleed, both in the maintenance-dose group. There was no difference between the groups in the proportion of patients with excessive INRs or elevated D-dimer levels or in the median D-dimer level.

CONCLUSION

Resumption of warfarin after minor-moderately invasive procedures with two loading doses achieves therapeutic INR faster than does only maintenance dose.

Outcomes after arterial endovascular procedures performed in patients with an elevated international normalized ratio

BACKGROUND

Patients treated with anticoagulants frequently require urgent vascular procedures and elevated prothrombin time/international normalized ratio (INR) is traditionally thought to increase access site bleeding complications after sheath removal. We aimed to determine the safety of percutaneous arterial procedures on patients with a high INR in the era of modern ultrasound-guided access and closure device use.

METHODS

Patients undergoing arterial endovascular procedures at a single institution between October 2010 and November 2012 were reviewed (n = 1,333). We retrospectively analyzed all patients with an INR > 1.5. Venous procedures, lysis checks, and cases with no documented INR within 24 hr were excluded. Sixty-five patients with 91 punctures were identified. A comparison group was then generated from the last 91 patients intervened on with INR < 1.6. Demographics, intraoperative data, and postoperative complications were compared.

RESULTS

The demographics were similar. More Coumadin use and higher INR were found in the study group (71/91 and 0/91, P = 0.001; 2.3 and 1.1 sec, P = 0.001, respectively), but there was more antiplatelet use in the control group (68/91 and 51/91, P = 0.01). Intraoperatively, the sheath sizes, protamine use, closure device use, ultrasound guidance, brachial access, and procedure types were not statistically different. Sheath sizes ranged from 4 to 22F in the study group and 4 to 20F in the control group. Paradoxically, heparin was administered more frequently in the study group (64/91 and 50/91, P = 0.046). Bleeding complications occurred more commonly in the study group (3/91 and 1/91, P = 0.62), but this failed to reach significance and the overall complication rate in both groups was low.

CONCLUSIONS

Endovascular procedures may be performed safely with a low risk of bleeding complications in patients with an elevated INR. Ultrasound guidance and closure device use may allow these cases to be performed safely, but a larger series may be needed to confirm this.

Comparison of initial loading doses of 5 mg and 10 mg for warfarin therapy

CONTEXT: The question of what is the best loading dosage of warfarin when starting anticoagulant treatment has been under discussion for ten years. We were unable to find any comparative studies of these characteristics conducted here in Brazil. OBJECTIVE: To compare the safety and efficacy of two initial warfarin dosage regimens for anticoagulant treatment. METHODS: One-hundred and ten consecutive patients of both sexes, with indications for anticoagulation because of venous or arterial thromboembolism, were analyzed prospectively. During the first 3 days of treatment, these patients were given adequate heparin to keep aPTT (activated partial thromboplastin time) between 1.5 and 2.5, plus 5 mg of warfarin. From the fourth day onwards, their warfarin doses were adjusted using International Normalized Ratios (INR; target range: 2 to 3). This prospective cohort was compared with a historical series of 110 patients had been given 10 mg of warfarin on the first 2 days and 5 mg on the third day with adjustments based on INR thereafter. Outcomes analyzed were as follows: recurrence of thromboembolism, bleeding events and time taken to enter the therapeutic range. RESULTS: Efficacy, safety and length of hospital stay were similar in both samples. The sample that were given 10 mg entered the therapeutic range earlier (means: 4.5 days vs. 5.8 days), were on lower doses at discharge and had better therapeutic indicators at the first return appointment. CONCLUSIONS: The 10 mg dosage regimen took less time to attain the therapeutic range and was associated with lower warfarin doses at discharge and better INR at first out-patients follow-up visit.

Guidelines for gastroenterological endoscopy in patients undergoing antithrombotic treatment

Guidelines for gastroenterological endoscopy in patients undergoing antithrombotic treatment have been produced by the Japan Gastroenterological Endoscopy Society in collaboration with the Japan Circulation Society, the Japanese Society of Neurology, the Japan Stroke Society, the Japanese Society on Thrombosis and Hemostasis and the Japan Diabetes Society. Previous guidelines from the Japan Gastroenterological Endoscopy Society have focused primarily on prevention of hemorrhage after gastroenterological endoscopy as a result of continuation ofantithrombotic therapy, without considering the associated risk of thrombosis. The new edition of the guidelines includes discussions of gastroenterological hemorrhage associated with continuation of antithrombotic therapy, as well as thromboembolism associated with withdrawal of antithrombotic therapy.

Cardiac rhythm device surgery with uninterrupted oral anticoagulation

Current guidelines recommend interrupting anticoagulation and bridging therapy with heparin or low-molecular-weight heparin for cardiac rhythm device surgeries in patients with high thrombotic risk. However, there are some studies that suggest continuing warfarin may be safe. The study by Birnie et al. investigates this important clinical question in a randomized controlled trial setting. They randomly assigned 681 patients with high thrombotic risk (5% or more per year), in 18 centers, to receive either stopping warfarin combined with heparin bridging (standard of care) or continued uninterrupted warfarin therapy for cardiac rhythm device surgery. The trial was terminated after a second prespecified interim analysis by the data and safety monitoring board. Clinically significant device-pocket hematoma was noted in 12 out of 343 patients (3.5%) in the uninterrupted warfarin group, compared with 54 out of 338 (16.0%) in the heparin-bridging group (relative risk: 0.19; 95% CI: 0.10-0.36; p < 0.001). Uninterrupted warfarin was associated with better patient satisfaction, and there was no significant difference in thromboembolic or surgical complications between the two groups. These results demonstrate that device surgeries can be safely performed with continued warfarin, and bridging with heparin is associated with high risk of device-pocket hematoma.

Warfarin initiation nomograms for venous thromboembolism

BACKGROUND

Venous thromboembolism (VTE) is a common condition in hospital patients. Considerable controversy is ongoing regarding optimal initial warfarin dosing for patients with acute deep venous thrombosis (DVT) and pulmonary embolism (PE). Achieving a therapeutic international normalized ratio (INR) with warfarin as soon as possible is important because this minimizes the duration of parenteral medication necessary to attain immediate anticoagulation, and it potentially decreases the cost and inconvenience of treatment. Although a 5-mg loading-dose nomogram tends to prevent excessive anticoagulation, a 10-mg loading-dose nomogram may achieve a therapeutic INR more quickly.

OBJECTIVES

To evaluate the efficacy of a 10-mg warfarin nomogram compared with a 5-mg warfarin nomogram among patients with VTE.

SEARCH METHODS

The Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched January 2013) and the Cochrane Central Register of Controlled Trials (CENTRAL) (2012, Issue 12). The review authors searched PubMed (last searched 10 April 2013) and LILACS (last searched 28 February 2013). In addition, the review authors contacted pharmaceutical companies.

SELECTION CRITERIA

Randomized controlled studies comparing warfarin initiation nomograms of 10 and 5 mg in patients with VTE.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. The review authors contacted study authors for additional information.

MAIN RESULTS

Four trials involving 494 participants were included. Three studies involving 383 participants provided data on the proportion of participants who had achieved a therapeutic INR by day five. Significant benefit of a 10-mg warfarin nomogram was observed (risk ratio [RR] 1.27, 95% confidence interval [CI] 1.05 to 1.54), although with substantial heterogeneity (I(2) = 90%). The review authors analyzed each study separately because it was not possible to perform a subgroup analysis. One study showed significant benefit of a 10-mg warfarin nomogram for the proportion of outpatients with VTE who had achieved a therapeutic INR by day five (RR 1.78, 95% CI 1.41 to 2.25), with the number needed to treat for an additional beneficial outcome (NNTB = 3, 95% CI 2 to 4); another study showed significant benefit of a 5-mg warfarin nomogram in outpatients with VTE (RR 0.58, 95% CI 0.36 to 0.93) with NNTB = 5 (95% CI 3 to 28); a third study showed no difference (RR 1.08, 95% CI 0.65 to 1.80). No difference was observed in recurrent venous thromboembolism (RVTE) at 90 days when the warfarin nomogram of 10 mg was compared with the warfarin nomogram of 5 mg (RR 1.48, 95% CI 0.39 to 5.56); no difference was observed in major bleeding at 14 days (RR 1.69, 95% CI 0.22 to 13.04) and at 90 days (RR 0.62, 95% CI 0.10 to 3.78). No difference was observed in minor bleeding at 14 to 90 days (RR 0.32, 95% CI 0.15 to 1.83) or in length of hospital stay (mean difference [MD] -2.30 days, 95% CI -7.96 to 3.36).

AUTHORS' CONCLUSIONS

In patients with acute thromboembolism (DVT or PE) aged 18 years or older, considerable uncertainty surrounds the use of a 10-mg or a 5-mg loading dose for initiation of warfarin to achieve an INR of 2.0 to 3.0 on the fifth day of therapy. Heterogeneity among analyzed studies limits certainty surrounding optimal warfarin initiation nomograms.

An acenocoumarol dose algorithm based on a South-Eastern European population

AIM

To develop and validate an algorithm for the prediction of therapeutic dose of acenocoumarol in Romanian patients.

METHODS

The inclusion criteria for entry to the study was age ≥ 18 years and starting acenocoumarol treatment for at least one of the following clinical indications: acute deep vein thrombosis of the lower limbs, persistent or permanent atrial fibrillation, and/or the presence of valvular prostheses requiring prolonged oral anticoagulant therapy. The patients were followed up for 3 months. Patients admitted to the internal medicine, cardiology, and geriatrics wards of the Municipal Clinical Hospital, Cluj-Napoca and "Niculae Stăncioiu" Heart Institute between October 2009 and June 2011 who fulfilled the inclusion criteria were included in the study. Clinical and demographic data that could influence the acenocoumarol stable dose were recorded for each patient. Genetic analysis included the genotyping the CYP2C9*2 and *3, and the VKORC1 -1693 G > A polymorphisms. The patients were randomly divided into two groups: (1) the main group on which the development of the clinical and genetic algorithms for acenocoumarol dose prediction was based; (2) the validation group.

RESULTS

The study included 301 patients, of whom 155 were women (51.5 %) and 146 were men (48.5 %). The median age of the patient cohort was 66 (women, 57; men, 73) years. After randomization the main group comprised 200 patients (66.4 %) and the validation group 101 patients (33.6 %). Age and body mass index explained 18.8 % (R (2)) of the variability in acenocoumarol weekly dose in patients in the main group. When the genetic data were added to the algorithm, the CYP2C9*2 and *3 polymorphisms and the VKORC1 -1693 G > A polymorphism accounted for 4.7 and 19. 6 % of acenocoumarol dose variability, respectively. For the main group, we calculated a mean absolute error of 5 mg/week (0.71 mg/day). In the validation group, clinical parameters explained 22.2 % of the weekly acenocoumarol dose variability. Genetic polymorphisms increased the R(2) coefficient to 32.8 %.

CONCLUSION

We have developed and validated an accurate algorithm for prediction of the stable therapeutic dose of acenocoumarol in a Romania population.

Transitions of care in patients receiving oral anticoagulants: general principles, procedures, and impact of new oral anticoagulants

BACKGROUND

Most patients requiring anticoagulation therapy while hospitalized will continue this therapy as outpatients. This transition can be associated with gaps in care related to anticoagulation therapy that increase the risk of adverse events, rehospitalizations, and death. Warfarin, the most commonly used oral anticoagulant, presents distinct management challenges, including drug-food and drug-drug interactions, a narrow therapeutic window, and the requirements for periodic blood monitoring and dose adjustments, particularly during the hospital discharge process.

PURPOSE

This review explores clinical challenges and potential solutions surrounding anticoagulation therapy with warfarin during transitions of care, as well as discusses newer anticoagulants that are approved or are in late stages of development for the prevention of thromboembolic events.

CONCLUSIONS

Diligence, careful planning, and close communication between patients and healthcare providers during and after discharge are required to ensure that patients remain adequately and safely anticoagulated with warfarin in the outpatient setting. New oral anticoagulants may offer the possibility of safer and simpler care for patients requiring anticoagulation.

CLINICAL IMPLICATIONS

We summarize the latest guidelines and recommendations for safe hospital discharge and apply them to the specific case of discharging a warfarin-treated patient. In addition, we discuss the new oral anticoagulants and their potential to offer more efficacious and easier-to-manage anticoagulation.

An update of consensus guidelines for warfarin reversal

• Despite the associated bleeding risk, warfarin is the most commonly prescribed anticoagulant in Australia and New Zealand. Warfarin use will likely continue for anticoagulation indications for which novel agents have not been evaluated and among patients who are already stabilised on it or have severe renal impairment. • Strategies to manage over-warfarinisation and warfarin during invasive procedures can reduce the risk of haemorrhage. • For most warfarin indications, the target international normalised ratio (INR) is 2.0-3.0 (venous thromboembolism and single mechanical heart valve excluding mitral). For mechanical mitral valve or combined mitral and aortic valves, the target INR is 2.5-3.5. • Risk factors for bleeding with warfarin use include increasing age, history of bleeding and specific comorbidities. • For patients with elevated INR (4.5-10.0), no bleeding and no high risk of bleeding, withholding warfarin with careful subsequent monitoring seems safe. • Vitamin K1 can be given to reverse the anticoagulant effect of warfarin. When oral vitamin K1 is used for this purpose, the injectable formulation, which can be given orally or intravenously, is preferred. • For immediate reversal, prothrombin complex concentrates (PCC) are preferred over fresh frozen plasma (FFP). Prothrombinex-VF is the only PCC routinely used for warfarin reversal in Australia and New Zealand. It contains factors II, IX, X and low levels of factor VII. FFP is not routinely needed in combination with Prothrombinex-VF. FFP can be used when Prothrombinex-VF is unavailable. Vitamin K1 is essential for sustaining the reversal achieved by PCC or FFP. • Surgery can be conducted with minimal increased risk of bleeding if INR ≤ 1.5. For minor procedures where bleeding risk is low, warfarin may not need to be interrupted. If necessary, warfarin can be withheld for 5 days before surgery, or intravenous vitamin K₁ can be given the night before surgery. Prothrombinex-VF use for warfarin reversal should be restricted to emergency settings. Perioperative management of anticoagulant therapy requires an evaluation of the risk of thrombosis if warfarin is temporarily stopped, relative to the risk of bleeding if it is continued or modified.

Optimal loading dose of warfarin for the initiation of oral anticoagulation

BACKGROUND

Warfarin is used as an oral anticoagulant. However, there is wide variation in patient response to warfarin dose. This variation, as well as the necessity of keeping within a narrow therapeutic range, means that selection of the correct warfarin dose at the outset of treatment is not straightforward.

OBJECTIVES

To assess the effectiveness of different initiation doses of warfarin in terms of time in-range, time to INR in-range and effect on serious adverse events.

SEARCH METHODS

We searched CENTRAL, DARE and the NHS Health economics database on The Cochrane Library (2012, Issue 4); MEDLINE (1950 to April 2012) and EMBASE (1974 to April 2012).

SELECTION CRITERIA

All randomised controlled trials which compared different initiation regimens of warfarin.

DATA COLLECTION AND ANALYSIS

Review authors independently assessed studies for inclusion. Authors also assessed the risk of bias and extracted data from the included studies.

MAIN RESULTS

We identified 12 studies of patients commencing warfarin for inclusion in the review. The overall risk of bias was found to be variable, with most studies reporting adequate methods for randomisation but only two studies reporting adequate data on allocation concealment. Four studies (355 patients) compared 5 mg versus 10 mg loading doses. All four studies reported INR in-range by day five. Although there was notable heterogeneity, pooling of these four studies showed no overall difference between 5 mg versus 10 mg loading doses (RR 1.17, 95% CI 0.77 to 1.77, P = 0.46, I(2) = 83%). Two of these studies used two consecutive INRs in-range as the outcome and showed no difference between a 5 mg and 10 mg dose by day five (RR 0.86, 95% CI 0.62 to 1.19, P = 0.37, I(2 )= 22%); two other studies used a single INR in-range as the outcome and showed a benefit for the 10 mg initiation dose by day 5 (RR 1.49, 95% CI 1.01 to 2.21, P = 0.05, I(2 )= 72%). Two studies compared a 5 mg dose to other doses: a 2.5 mg initiation dose took longer to achieve the therapeutic range (2.7 versus 2.0 days; P < 0.0001), but those receiving a calculated initiation dose achieved a target range quicker (4.2 days versus 5 days, P = 0.007). Two studies compared age adjusted doses to 10 mg initiation doses. More elderly patients receiving an age adjusted dose achieved a stable INR compared to those receiving a 10 mg initial dose (and Fennerty regimen). Four studies used genotype guided dosing in one arm of each trial. Three studies reported no overall differences; the fourth study, which reported that the genotype group spent significantly more time in-range (P < 0.001), had a control group whose INRs were significantly lower than expected. No clear impacts from adverse events were found in either arm to make an overall conclusion.

AUTHORS' CONCLUSIONS

The studies in this review compared loading doses in several different situations. There is still considerable uncertainty between the use of a 5 mg and a 10 mg loading dose for the initiation of warfarin. In the elderly, there is some evidence that lower initiation doses or age adjusted doses are more appropriate, leading to fewer high INRs. However, there is insufficient evidence to warrant genotype guided initiation.

Upper extremity deep vein thrombosis

A 56-year-old female, recently (3 months) diagnosed with chronic kidney disease (CKD), on maintenance dialysis through jugular hemodialysis lines with a preexisting nonfunctional mature AV fistula made at diagnosis of CKD, presented to the hospital for a peritoneal dialysis line. The recently inserted indwelling dialysis catheter in left internal jugular vein had no flow on hemodialysis as was the right-sided catheter which was removed a day before insertion of the left-sided line. The left-sided line was removed and a femoral hemodialysis line was cannulated for maintenance hemodialysis, and the next day, a peritoneal catheter was inserted in the operation theater. However, 3 days later, there was progressive painful swelling of the left hand and redness with minimal numbness. The radial artery pulsations were felt. There was also massive edema of forearm, arm and shoulder region on the left side. Doppler indicated a steal phenomena due to a hyperfunctioning AV fistula for which a fistula closure was done. Absence of relief of edema prompted a further computed tomography (CT) angiogram (since it was not possible to evaluate the more proximal venous segments due to edema and presence of clavicle). Ct angiogram revealed central vein thrombosis for which catheter-directed thrombolysis and venoplasty was done resulting in complete resolution of signs and symptoms. Upper extremity DVT (UEDVT) is a very less studied topic as compared to lower extremity DVT and the diagnostic and therapeutic modalities still have substantial areas that need to be studied. We present a review of the present literature including incidences, diagnostic and therapeutic modalities for this entity. Data Sources: MEDLINE, MICROMEDEX, The Cochrane database of Systematic Reviews from 1950 through March 2011.