Hemorrhagic complications of anticoagulant treatment

Subretinal hemorrhages associated with age-related macular degeneration in patients receiving anticoagulation or antiplatelet therapy

PURPOSE

To evaluate the incidence of and risk factors for subretinal hemorrhages in age-related macular degeneration (AMD) patients on anticoagulation or antiplatelet therapy.

DESIGN

Retrospective, observational case series.

METHODS

We retrospectively reviewed the medical and photographic records of 71 consecutive patients who sought treatment at our institution with acute subretinal hemorrhages complicating age-related macular degeneration. The size of the subretinal hemorrhage was measured in standardized Macular Photocoagulation Study disc areas. Data on the use of medications and medical indications for anticoagulation and antiplatelet therapy were obtained.

RESULTS

Overall, patients receiving antithrombotic therapy had a significantly larger subretinal hemorrhage size (mean, 9.71 disc areas) than patients not receiving anticoagulant or antiplatelet therapy (mean, 2.99 disc areas). Subgroup analysis revealed that both antiplatelet (P < .0001) and anticoagulant therapy (P = .003) were associated with a significantly larger bleeding size. Moreover, subgroup analysis among patients with arterial hypertension revealed that individuals receiving antithrombotic therapy had a statistically significantly larger hemorrhage size than hypertensive patients who did not receive anticoagulants or antiplatelet agents (P < .0001).

CONCLUSIONS

Our results indicate that anticoagulants and antiplatelet agents are strongly associated with the development of large subretinal hemorrhages in AMD patients. Moreover, arterial hypertension is a strong risk factor for large subretinal hemorrhages in AMD patients receiving anticoagulants or antiplatelet agents. Physicians should be aware of an increased risk of extensive subretinal hemorrhage in AMD patients when deciding on the initiation and duration of anticoagulant and antiplatelet therapy.

Determination of plasma warfarin concentrations in Korean patients and its potential for clinical application

BACKGROUND

Warfarin is a widely used oral anticoagulant with broad within- and between-individual dose requirements. Warfarin concentrations can be monitored by assessing its pharmacologic effects on International Normalized Ratio (INR). However, this approach has not been applied in the routine clinical management of patients receiving warfarin therapy. We performed a plasma warfarin assay using high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) to determine if such an assay can be utilized in routine clinical practice.

METHODS

We included a total of 105 patients with atrial fibrillation, and who were receiving warfarin for more than 1 yr. The plasma concentrations of total warfarin and 7-hydroxywarfarin were determined by HPLC-MS/MS (Waters, UK). We assessed the association between warfarin dose, concentration, and INR as well as the effects of these factors on warfarin concentrations.

RESULTS

The mean maintenance dose of warfarin in 105 patients was 4.1 +/-1.3 mg/day (range, 1.7-8.0 mg/day) and their mean plasma warfarin concentration was 1.3+/-0.5 mg/L. We defined a concentration range of 0.6-2.6 mg/L (corresponding to the 2.5th to 97.5th percentile range of the Plasma warfarin levels in the 74 patients showing INR within target range) as the therapeutic range for warfarin. The correlation of warfarin dose with warfarin concentration (r(2)=0.259, P<0.001) was higher than that with INR (r(2)=0.029, P=0.072).

CONCLUSIONS

There was a significant correlation between warfarin dose and plasma warfarin concentrations in Korean patients with atrial fibrillation. Hence, plasma warfarin monitoring can help determine dose adjustments and improve our understanding of individual patient response to warfarin treatment.

The surgical treatment of atrial fibrillation

Atrial fibrillation is a complex disease affecting a significant portion of the general population. Although medical therapy is the mainstay of treatment, intervention plays an important role in selected patients. The Cox-Maze procedure is the gold standard for the surgical treatment of atrial fibrillation and has more than 90% success in eliminating atrial fibrillation. Ablation technologies have played a key role in simplifying this technically demanding procedure and making it available to more patients. A myriad of new lesion sets and approaches were introduced over the last decade which has made the operative treatment of atrial fibrillation less invasive and more confusing.

Percutaneous closure of left atrial appendage to prevent embolic events in high-risk patients with chronic atrial fibrillation

BACKGROUND

Percutaneous closure of the left atrial appendage (LAA) is a novel alternative for the treatment of patients with atrial fibrillation (AF) and with a high risk of stroke who are not eligible for long-term anticoagulation therapy. The aim of this study was to asses the safety, feasibility, and long-term efficacy of this procedure.

METHODS

From July 2004 to June 2007, 20 patients (13 male, mean age 69 +/- 8 years) with non-valvular AF (NV-AF) underwent LAA percutaneous closure using the PLAATO system, implanted through a transeptal access. All patients had contraindications to anticoagulant therapy and were at high risk for cardioembolic stroke (mean CHADS(2) score 3 +/- 1.2). A trans-thoracic echocardiogram was performed at 1, 3, and every 6 months after the procedure, whereas a trans-oesophageal echocardiogram (TOE) was scheduled at 6 months. After 24 months, a phone interview was obtained.

RESULTS

All procedures were successfully performed in 18 patients. In two patients, LAA closure was not feasible for the presence of a multilobed LAA. Two patients underwent percutaneous closure of patent foramen ovale in the same session. In one patient, the procedure was complicated by cardiac perforation with pericardial effusion, treated with pericardiocentesis. At a mean follow up of 40 +/- 10 months, no embolic events occurred. One patient died, after 36 months, for gastric cancer. TOE examination showed the complete exclusion of the LAA in all patients.

CONCLUSIONS

Percutaneous closure of LAA is safe and efficacious to prevent stroke in patients with NV-AF at high risk for cardioembolic events, with contraindications to anticoagulant therapy.

The future of interventional cardiology lies in the left atrium

The historic focus of interventional cardiology has been on treating atherosclerotic coronary artery disease. Balloons, stents, and debulking devices have been the mainstay tools of the interventionalist. However, as engineering skills have developed and clinical techniques have improved, new clinical avenues for the interventionalist beyond the coronary vessels are starting to evolve. One of the most opportunistic areas in cardiology for the interventionalist is the left atrium where treatment of clinically important issues such as mitral regurgitation, left atrial thrombus, atrial fibrillation, patent foramen ovale, and atrial septal defect may be approached. Additionally, the left atrium is a source of important hemodynamic information that can be captured with new implantable devices. While in the past the trans-septal puncture has been infrequently used, the future may hold this technique as one of the most common. The following manuscript describes the status of some of the newest opportunities for interventionalists that lie beyond atherosclerotic disease and within the left atrium.

Management of intracranial bleeding in anticoagulated patients

Intracranial haemorrhage is a life-threatening complication of anticoagulation. When the anticoagulation is for a mechanical heart valve the risks of further bleeding on warfarin need to be balanced against the risks of thromboembolism from an unprotected valve.

Does preoperative atrial fibrillation increase the risk for mortality and morbidity after coronary artery bypass grafting?

OBJECTIVES

Preoperative atrial fibrillation has been associated with less favorable outcomes in patients undergoing coronary artery bypass grafting. However, it was never investigated in a large cohort of patients using a national database. This study aims to (1) identify the effect of atrial fibrillation on operative mortality and morbidity in patients undergoing isolated coronary artery bypass grafting and (2) identify the potential effect of atrial fibrillation on patients with decreased left ventricular ejection fraction (<or=40%).

METHODS

The Society of Thoracic Surgeons National Adult Cardiac Surgery Database was used for patients with coronary artery disease undergoing isolated coronary artery bypass grafting (n = 281,567). The association between atrial fibrillation and outcomes was estimated within 3 categories of low (ejection fraction, <40%), moderate (ejection fraction, 40%-55%), or normal (ejection fraction, >55%) systolic function.

RESULTS

Patients with atrial fibrillation were found to be older and have a higher incidence of comorbidities. A higher incidence of all major complications and mortality after surgical intervention was documented. An interaction between atrial fibrillation and an ejection fraction of greater than 40% for mortality, stroke, prolonged ventilation, and prolonged length of stay was identified.

CONCLUSIONS

Our findings suggest that preoperative atrial fibrillation is associated with an increased risk for perioperative mortality and morbidity in patients undergoing coronary artery bypass grafting. The negative effect of atrial fibrillation might be more significant in patients undergoing coronary artery bypass grafting with an ejection fraction of greater than 40%. Both the EuroSCORE and, until recently, the Society of Thoracic Surgeons risk calculator do not include atrial fibrillation as a potential risk modifier; however, based on this study, it should be identified as a variable to be investigated and incorporated into future risk calculators.

Gastrointestinal bleeding in the setting of anticoagulation and antiplatelet therapy

GOAL

To review the literature on the significance, risk factors, and management of occult and gross gastrointestinal (GI) bleeding in patients on antiplatelets and/or anticoagulants.

STUDY

Relevant original and review articles and their bibliographies were analyzed. Estimates of risks and therapeutic outcomes were obtained from randomized trials, whereas risk factor identification was gathered from cross-control and prospective cohort studies.

RESULTS

Antiplatelets and anticoagulants do not diminish the positive predictive value of fecal occult blood testing to find GI pathology. They increase the risk of gross GI bleeding, and predictors of hemorrhage include history of GI bleeding or ulcer disease, higher intensity of anticoagulation, combination therapy, and presence of comorbid conditions. A bleeding site is identified in most patients with peptic ulcer being the most common. In case of significant bleeding, complete or partial reversal of anticoagulation is undertaken on the basis of the balance of risks between bleeding and thromboembolic events. Early endoscopy can reveal lesions requiring endoscopic hemostasis, which can be performed in the setting of low-intensity anticoagulation. In patients with history of peptic disease or bleeding from an acid-related lesion, proton-pump inhibitors and Helicobacter pylori eradication reduce the risk of upper GI bleeding even when antiplatelet therapy is continued.

CONCLUSIONS

Predictors of bleeding on antiplatelets and/or antithrombotics therapy have been identified, but formulation and validation of a GI bleeding index for stratification of risk in individual patients is suggested. Reversal of anticoagulation in bleeding patients is associated with a low risk of thromboembolic events and permits the performance of diagnostic and therapeutic endoscopy. Proton-pump inhibitors and H. pylori eradication reduce the risk of rebleeding in those with acid-related disease.

An Unusual Complication of EVAR, Spontaneous Rectus Sheath Hematoma: A Case Report

OBJECTIVE

To report a successful conservative management in a case of spontaneous rectus sheath hematoma (SRSH) after Endovascular Aneurysmal Repair (EVAR) of infrarenal Abdominal Aortic Aneurysm (AAA).

CASE PRESENTATION

An 84-year-old woman with a 6 cm in diameter infrarenal AAA underwent EVAR at our hospital. During the procedure, intravenous heparin was administered to keep the activated clotting time around 300 seconds. One hour after the procedure, the patient complained of pain on her right side abdomen. Physical examination revealed a tender mass in the right lower abdominal wall. Laboratory studies showed a fall in hemoglobin from 12.7 g/dl to 9.3 g/dl. Ultrasound (US) examination demonstrated an 8 × 5 cm hematoma within the right rectus muscle. Follow-up US examination revealed that the hematoma had enlarged and a computed tomography (CT) examination of the lower abdomen was performed. CT scan showed a smooth-shaped mass within the layers of the anterolateral abdominal wall leading to enlargement of the right rectus abdominis muscle without signs of active bleeding. A conservative management was considered.

RESULT

The clinical course was uneventful with a stable hemodynamic state. The patient was discharged 12 days later and was doing well at the 2 week follow-up.

CONCLUSION

Spontaneous rectus sheath hematoma is an unusual complication of a patient on anticoagulant therapy during EVAR. A prompt radiological investigation may prevent unnecessary surgical procedures in this unusual complication.

[Level of knowledge among patients treated with oral anticoagulant]

Hospitalization attributable to gastrointestinal and other major bleeding is frequently associated with acenocoumarol treatment.

AIMS

To assess the level of knowledge among patients in respect to harmful adverse effects, interactions with medication and nutrition regarding acenocoumarol treatment.

METHODS

Questionnaires consisting of 66 questions were completed in offices of family doctors (77), and during consultations at the 3rd Department of Internal Medicine (80).

RESULTS

157 patients (male:female=45:55; age=65.5 years) were involved. In the group informed by the whole team (doctors, nurses and dietitians) everyone heard about the possible adverse effects. In the group where family doctors or other specialists provided information, 14.5% or 31.1% did not hear about any side-effect. The importance of diet was unknown by 71.4% of the patients. The knowledge of interactions between acenocoumarol and other medications is low: aspirin was known by 24.4%, analgetics by 23.0% and vitamin K by 18.6% of the patient.

CONCLUSIONS

Regarding acenocoumarol treatment, patients' knowledge should be enlarged. However, it can be significantly improved by the contribution of other team members such as nurses and dietitians.

Pharmacogenetics of warfarin: development of a dosing algorithm for brazilian patients

A dosing algorithm including genetic (VKORC1 and CYP2C9 genotypes) and nongenetic factors (age, weight, therapeutic indication, and cotreatment with amiodarone or simvastatin) explained 51% of the variance in stable weekly warfarin doses in 390 patients attending an anticoagulant clinic in a Brazilian public hospital. The VKORC1 3673G>A genotype was the most important predictor of warfarin dose, with a partial R(2) value of 23.9%. Replacing the VKORC1 3673G>A genotype with VKORC1 diplotype did not increase the algorithm's predictive power. We suggest that three other single-nucleotide polymorphisms (SNPs) (5808T>G, 6853G>C, and 9041G>A) that are in strong linkage disequilibrium (LD) with 3673G>A would be equally good predictors of the warfarin dose requirement. The algorithm's predictive power was similar across the self-identified "race/color" subsets. "Race/color" was not associated with stable warfarin dose in the multiple regression model, although the required warfarin dose was significantly lower (P = 0.006) in white (29 +/- 13 mg/week, n = 196) than in black patients (35 +/- 15 mg/week, n = 76).

Antithrombotic therapy for venous thromboembolic disease: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

This chapter about treatment for venous thromboembolic disease is part of the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Grade 1 recommendations are strong and indicate that the benefits do or do not outweigh risks, burden, and costs. Grade 2 suggests that individual patient values may lead to different choices (for a full understanding of the grading, see "Grades of Recommendation" chapter). Among the key recommendations in this chapter are the following: for patients with objectively confirmed deep vein thrombosis (DVT) or pulmonary embolism (PE), we recommend anticoagulant therapy with subcutaneous (SC) low-molecular-weight heparin (LMWH), monitored IV, or SC unfractionated heparin (UFH), unmonitored weight-based SC UFH, or SC fondaparinux (all Grade 1A). For patients with a high clinical suspicion of DVT or PE, we recommend treatment with anticoagulants while awaiting the outcome of diagnostic tests (Grade 1C). For patients with confirmed PE, we recommend early evaluation of the risks to benefits of thrombolytic therapy (Grade 1C); for those with hemodynamic compromise, we recommend short-course thrombolytic therapy (Grade 1B); and for those with nonmassive PE, we recommend against the use of thrombolytic therapy (Grade 1B). In acute DVT or PE, we recommend initial treatment with LMWH, UFH or fondaparinux for at least 5 days rather than a shorter period (Grade 1C); and initiation of vitamin K antagonists (VKAs) together with LMWH, UFH, or fondaparinux on the first treatment day, and discontinuation of these heparin preparations when the international normalized ratio (INR) is > or = 2.0 for at least 24 h (Grade 1A). For patients with DVT or PE secondary to a transient (reversible) risk factor, we recommend treatment with a VKA for 3 months over treatment for shorter periods (Grade 1A). For patients with unprovoked DVT or PE, we recommend treatment with a VKA for at least 3 months (Grade 1A), and that all patients are then evaluated for the risks to benefits of indefinite therapy (Grade 1C). We recommend indefinite anticoagulant therapy for patients with a first unprovoked proximal DVT or PE and a low risk of bleeding when this is consistent with the patient's preference (Grade 1A), and for most patients with a second unprovoked DVT (Grade 1A). We recommend that the dose of VKA be adjusted to maintain a target INR of 2.5 (INR range, 2.0 to 3.0) for all treatment durations (Grade 1A). We recommend at least 3 months of treatment with LMWH for patients with VTE and cancer (Grade 1A), followed by treatment with LMWH or VKA as long as the cancer is active (Grade 1C). For prevention of postthrombotic syndrome (PTS) after proximal DVT, we recommend use of an elastic compression stocking (Grade 1A). For DVT of the upper extremity, we recommend similar treatment as for DVT of the leg (Grade 1C). Selected patients with lower-extremity (Grade 2B) and upper-extremity (Grade 2C). DVT may be considered for thrombus removal, generally using catheter-based thrombolytic techniques. For extensive superficial vein thrombosis, we recommend treatment with prophylactic or intermediate doses of LMWH or intermediate doses of UFH for 4 weeks (Grade 1B).

Risk factors for bleeding during anticoagulation of atrial fibrillation in older and younger patients in clinical practice

BACKGROUND

The prevalence of atrial fibrillation increases with age, affecting approximately 5% of people aged >65 years and almost 10% of people aged >80 years.

OBJECTIVE

The goal of this study was to identify risk factors for bleeding during warfarin treatment of nonvalvular atrial fibrillation (NNVAF) in older patients (those aged >or=75 years) compared with younger patients (those aged <75 years) in clinical practice.

METHODS

All patients with NVAF newly started on warfarin at an anticoagulation clinic in a large university hospital were included in this prospective observational study. Patient details were recorded at their first visit; details of any bleeding events were recorded via telephone interview every 4 to 6 weeks for a minimum of 10 months. Patients were divided into 2 groups (ie, those >or=75 years old and those <75 years old). Logistic regression analysis was used to identify risk factors for bleeding.

RESULTS

A total of 402 patients were included in the study. Group I comprised 203 patients <75 years old (mean [SD] age, 64.33 [8.33] years) and group II comprised 199 patients >or=75 years old (mean [SD] age, 80.44 [3.99] years). Follow-up ranged from 1 to 31 months (mean [SD], 19 [8.11] months). For major bleeding, number of medications was a significant risk factor in older patients (odds ratio [OR], 3.0; 95% CI, 1.2-7.8 [P = 0.02 ]) and range of the international normalized ratio (INR) was a significant risk factor in both groups. For every unit increase in the range of INR, the odds of major bleeding increased by 0.6 (OR, 1.6; 95% CI, 1.2-2.4 [P = 0.03 ]) in younger patients and by 0.4 (OR, 1.4; 95% CI, 1.07-1.99 [P = 0.04 ])in older patients. For minor bleeding, history of hypertension was the only significant risk factor in older patients (OR, 3.3; 95% CI, 1.3-8.1 [P = 0.01 ]), while history of ischemic heart disease was the only risk factor in younger patients (OR, 1.9; 95% CI, 1.1-5.4 [P = 0.04 ]).

CONCLUSIONS

Bleeding pattern was similar in both age groups regarding severity, onset, anatomic site of bleeding, and INR values during the bleeding event. Risk factors for episodes of major bleeding, which are more of a clinical concern, are potentially modifiable. They include quality of anticoagulation control in both groups and number of medications in the older age group.

Factors affecting the severity of spontaneous retroperitoneal hemorrhage in anticoagulated patients

BACKGROUND

Clinical manifestations of spontaneous retroperitoneal hemorrhage (SRH) range from a small decrease in hemoglobin to hypotension requiring transfer to the intensive care unit (ICU). Our goal was to identify which anticoagulated patients are at increased risk for SRH and its complications.

METHODS

We conducted a retrospective review of 180 patients with SRH. Age, sex, presence of comorbidities, hemoglobin decrease, transfusion requirement, ICU stay, and length of ICU stay were recorded. Patients were divided into 5 groups based on their anticoagulants: (1) heparin and Coumadin, (2) heparin only, (3) Coumadin only, (4) heparin +/- Coumadin and aspirin (ASA) +/- Plavix, and (5) other anticoagulants.

RESULTS

Group 4 patients were more likely to require ICU admission and have longer ICU stay compared to others (P = .021 & P < or = 0.0001, respectively, by Kruskall-Wallis test). Patients with coronary artery disease were more likely to require ICU admission (P = .01 by chi-square test).

CONCLUSIONS

Patients on combined anticoagulant-antiplatelet therapy are more likely to require ICU admission and longer ICU stay. Close observation is warranted in these patients for early detection of SRH.

Genetic determinants of response to warfarin during initial anticoagulation

BACKGROUND

Genetic variants of the enzyme that metabolizes warfarin, cytochrome P-450 2C9 (CYP2C9), and of a key pharmacologic target of warfarin, vitamin K epoxide reductase (VKORC1), contribute to differences in patients' responses to various warfarin doses, but the role of these variants during initial anticoagulation is not clear.

METHODS

In 297 patients starting warfarin therapy, we assessed CYP2C9 genotypes (CYP2C9 *1, *2, and *3), VKORC1 haplotypes (designated A and non-A), clinical characteristics, response to therapy (as determined by the international normalized ratio [INR]), and bleeding events. The study outcomes were the time to the first INR within the therapeutic range, the time to the first INR of more than 4, the time above the therapeutic INR range, the INR response over time, and the warfarin dose requirement.

RESULTS

As compared with patients with the non-A/non-A haplotype, patients with the A/A haplotype of VKORC1 had a decreased time to the first INR within the therapeutic range (P=0.02) and to the first INR of more than 4 (P=0.003). In contrast, the CYP2C9 genotype was not a significant predictor of the time to the first INR within the therapeutic range (P=0.57) but was a significant predictor of the time to the first INR of more than 4 (P=0.03). Both the CYP2C9 genotype and VKORC1 haplotype had a significant influence on the required warfarin dose after the first 2 weeks of therapy.

CONCLUSIONS

Initial variability in the INR response to warfarin was more strongly associated with genetic variability in the pharmacologic target of warfarin, VKORC1, than with CYP2C9.

Intestinal obstruction due to spontaneous intramural hematoma of the small intestine during warfarin use: a report of two cases

Warfarin-dependent spontaneous intramural hematoma of the small intestine is a rare complication. The first symptom is usually abdominal pain, frequently accompanied by nausea and vomiting. In some cases, concomitant gastrointestinal bleeding might be seen. Ultrasonography and computed tomography are the most useful radiographic methods for the diagnosis of an intramural hematoma of the intestines. Although it is usually treated conservatively, surgical intervention is required in cases involving active bleeding, intestinal obstruction, or acute abdominal symptoms. Here we present two patients who were treated surgically. Both patients had intestinal obstruction and ischemia, and one had concomitant gastrointestinal bleeding and intussusception due to an intramural hematoma.

Primary prevention of venous thromboembolism in elderly medical patients

Primary prophylaxis with the use of an effective and safe intervention appears the best approach of venous thromboembolism (VTE) management in medical elderly patients, the most affected by VTE. With increasing life expectancy, prevention of VTE, particularly in elderly patients, will arise as a major public health problem. Few well designed clinical trials evaluating thromboprophylaxis in medical settings were conducted in the specific population of geriatric patients. However, among the several pharmacological treatments evaluated, low molecular weight heparins enoxaparin 40 mg daily or dalteparin 5000 IU daily appeared effective and safe in the prevention of VTE in elderly patients. Despite available data, and recommendations for VTE prevention in medical patients, thromboprophylaxis is underused or misused in practice. Heterogeneity of clinical studies, selected populations, concern about bleeding, and lack of a clear clinical benefit are some of the reasons that could explain the gap between theory and practice. In this review, after a brief report of epidemiologic data and specificities of VTE in elderly patients, the authors discuss the available results of VTE primary prevention trials for elderly medical patients, the limitations of these data, and the challenges to improve the practice and to reduce the incidence of this frequent but preventable disease.

[Use of rFVIIa (Novoseven) in the case of a patient with mitral valvular prothesis and anticoagulant accident]

We report the case of an haemorrhagic shock observed in a woman who received heparin for a cardiac valve in mitral position, efficiently treated with rFVIIa. The haemorrhagic complications under anticoagulation treatment remain rare, but can lead to real therapeutic dilemma. The use of rFVIIa has been evaluated in different clinical situations, including traumatic or post-operative haemorrhagic shock. The use of rFVIIa in the treatment of haemorrhagic complication under anticoagulation treatment is discussed.

Bridging therapy in patients on long-term oral anticoagulants who require surgery: the Prospective Peri-operative Enoxaparin Cohort Trial (PROSPECT)

BACKGROUND

The peri-operative management of patients on oral anticoagulants (OACs) is a common clinical problem. Our aim was to determine the incidence of major bleeding during peri-operative administration of treatment-dose enoxaparin and the impact of the extensiveness of the procedure on the risk of bleeding.

METHODS

We performed a prospective cohort study of 260 patients at 24 North American sites on OACs for atrial fibrillation or a history of deep vein thrombosis (DVT) requiring invasive or surgical procedures whose treating physician felt that bridging therapy was required. Warfarin was withheld, and once-daily s.c. enoxaparin (1.5 mg kg(-1)) was given peri-operatively. Patients were followed for 28 days after OAC was therapeutic.

RESULTS

Major bleeding was observed in nine of 260 patients (3.5%, 95% CI: 1.6-6.5). The bleeding risk varied markedly by extensiveness of procedure: the incidence of major bleeding for invasive procedures, minor surgery and major surgery was 0.7% (95% CI: 0.02-3.7), 0% (95% CI: 0-5.0), and 20.0% (95% CI: 9.1-35.7), respectively. There were five thromboembolic events in total (1.9%, 95% CI: 0.6-4.4). There were four arterial events (2.3%, 95% CI: 0.6-5.7) in 176 patients with atrial fibrillation, and one venous event (1.0%, 95% ci: 0.03-5.7) in 96 patients with prior DVT/ CONCLUSIONS: Bridging therapy with once-daily therapeutic-dose enoxaparin administered primarily in an outpatient setting has a low incidence of major bleeding for patients undergoing invasive procedures and minor surgery. Further studies are needed to optimize the bridging strategy for patients undergoing major surgery.

Warfarin in patients with stroke and reasons for discontinuation

BACKGROUND

Reasons for warfarin prescription in patients who have had ischemic stroke, and its discontinuation, are complex and unique for each individual patient.

OBJECTIVE

We sought to discover the reasons for discontinuation of warfarin therapy in patients followed up in a medical center antithrombosis clinic after stroke occurrence.

MATERIALS

In all, 229 patients on warfarin therapy with history of stroke were followed up in our antithrombosis clinic between January 1997 and March 2003. Of these patients, 132 were identified as having left the medical center antithrombosis clinic. Reasons for discontinuation of therapy were noted. Patients on combination antiplatelet-warfarin therapy were identified, as were the reasons for antithrombotic therapy.

RESULTS

The most common reason for discontinuation of warfarin was noncompliance with therapy and failure to show up for scheduled visits to the antithrombosis clinic. Hemorrhage was rare and not solely attributed to anticoagulation alone. The complication rate for major hemorrhage was 2.18%, well within the accepted range for US antithrombosis clinics. This rate included those on combination antiplatelet-anticoagulant therapy.

CONCLUSIONS

Combination therapy of warfarin and antiplatelet agents may not be dangerous in this group of patients. Careful assessment of patients on warfarin therapy in a medical center-based antithrombosis clinic assures close supervision of compliance, potential complications, and general medical and environmental conditions of the patient and allows for a controlled discontinuation of anticoagulation if necessary.

Intrinsic pathway of coagulation and arterial thrombosis

Formation of a fibrin clot is mediated by a group of tightly regulated plasma proteases and cofactors. While this system is essential for minimizing blood loss from an injured blood vessel (hemostasis), it also contributes to pathologic fibrin formation and platelet activation that may occlude vessels (thrombosis). Many antithrombotic drugs target key elements of the plasma coagulation mechanism such as thrombin and factor Xa, based on the premise that plasma elements contributing to thrombosis are primarily those involved in hemostasis. Recent studies with genetically altered mice raise questions about this paradigm. Deficiencies of the intrinsic pathway proteases factor XII and factor XI are not associated with abnormal hemostasis in mice, but impair formation of occlusive thrombi in arterial injury models, indicating that pathways not essential for hemostasis participate in arterial thrombosis. If factor XII or factor XI make similar contributions to thrombosis in humans, these proteases could be ideal targets for drugs to treat or prevent thromboembolic disease with minimal risk of therapy-associated bleeding.

Daily vitamin K supplementation improves anticoagulant stability

BACKGROUND

One of the causes of unstable anticoagulant control in patients using vitamin K antagonists is a fluctuating intake of vitamin K. Research suggests that patients with a low dietary intake of vitamin K have a less stable anticoagulant control than patients with a higher intake.

OBJECTIVES

To study whether supplementation with a low daily dose of vitamin K improves anticoagulant control.

METHODS

We performed a double-blind, randomized, placebo-controlled trial. 200 patients of the Leiden anticoagulation clinic, who used the vitamin K antagonist phenprocoumon, were randomized to receive either adjusted-dose phenprocoumon and 100 mug vitamin K once daily or adjusted-dose phenprocoumon and a placebo. Treatment duration was 24 weeks. The primary outcome was the percentage of time the International Normalized Ratio was within the therapeutic range.

RESULTS

The time in the therapeutic range was 85.5% in the placebo group and 89.5% in the vitamin K group (adjusted difference 3.6%; 95% CI -0.8% to 8.0%). The time below the therapeutic range was 3.1% in the placebo group and 2.1% in the vitamin K group (adjusted difference -0.7%; 95% CI -2.5% to 1.1%) and the time above the therapeutic range was 11.4% in the placebo group and 8.5% in the vitamin K group (adjusted difference -2.9%; 95% CI -6.9% to 1.1%). The relative risk (RR) of a maximal stability in the vitamin K group compared to the placebo group was 1.8 (95%, CI 1.1-2.7).

CONCLUSION

Supplementation of vitamin K antagonists with 100 mug vitamin K improves stability of anticoagulant therapy. Because the risk of side effects is inversely related to anticoagulant stability, such an improvement is likely to reduce the number of bleeding and thrombotic events.

The Use of Low-Dose Warfarin as Prophylaxis for Central Venous Catheter Thrombosis in Patients With Cancer: A Meta-Analysis

PURPOSE/OBJECTIVES

To determine whether the use of low-dose warfarin could reduce the incidence of thrombosis in patients with cancer who have a central venous catheter (CVC).

DATA SOURCES

MEDLINE, CINAHL, CANCERLIT, EMBASE, and the Cochrane Library.

DATA SYNTHESIS

Meta-analysis of four studies (N = 1,236 patients) revealed that 6.4% of warfarin-treated patients experienced a thrombotic event compared with 7.5% in the control (no treatment) group. The risk difference for thrombus formation was not significant (2.0%, confidence interval = -9.0% to 5.0%).

CONCLUSIONS

The administration of warfarin did not reduce the incidence of symptomatic or asymptomatic CVC-associated thrombosis in patients with cancer.

IMPLICATIONS FOR NURSING

Using research findings to inform clinical nursing practice is important in caring for patients and providing optimal and improved patient outcomes. Prophylactic use of low-dose warfarin may not prevent thrombus formation and is associated with potentially adverse patient outcomes.

Ximelagatran for Treatment and Prophylaxis of Recurrent Events in Deep Vein Thrombosis

The treatment of acute venous thromboembolism and prophylaxis of recurrent events with heparin/low molecular weight heparin followed by vitamin K antagonists is limited by several factors. Oral direct thrombin inhibitors (ODTIs) showed a better pharmacological activity and might be an alternative in the treatment of venous thromboembolism. The Thrombin Inhibition in Venous Thromboembolism (THRIVE) program performed some studies developing the ODTI ximelagatran for this indication, and it is presented in the overview. The aim of the THRIVE I study was the dose finding, and that of the THRIVE IV study the applicability in hemodynamic stabile pulmonary embolism. A prospective, randomized, double blind trial was performed to compare oral ximelagatran with enoxaparin/warfarin for a 6-month treatment of acute venous thrombosis (THRIVE II and V). A second double blind study compared ximelagatran with placebo over 18 months after a 6-month anticoagulant therapy of acute deep vein thrombosis. The efficacy and safety of treatment of patients with acute deep venous thrombosis who received 2 ∞ 36 mg ximelagatran was not inferior to that of patients who received a conventional anticoagulant for prophylaxis of recurrent events over 6 months. Ximelagatran 2 ∞ 24 mg significantly reduced recurrent thromboembolic events compared to placebo without increasing the risk for hemorrhage. A reversible symptomless increase of alanine aminotransferase occurs in 6% to 9.6% of patients between months 2 and 4. The results of the follow-up studies suggest that thromboembolic events may recur in patients with acute venous thromboembolism after termination of treatment with both vitamin K antagonists and ximelagatran.

Percutaneous devices for stroke prevention

The most important approaches to prevent cerebral ischemia by catheter technique are patent foramen ovale (PFO) closure in patients with a history of cryptogenic stroke and left atrial appendage (LAA) occlusion in atrial fibrillation (AF) patients. Over the past years, several new devices have been developed for these procedures. Results of randomized trials comparing device therapy, antiplatelet, or anticoagulation therapy are still not available. However, several nonrandomized studies have shown promising results. This article gives a review on the current results and techniques of the most commonly used devices as well as on new developments and approaches to catheter-based stroke prevention.

CYP2C19 polymorphism in Korean patients on warfarin therapy

This study was designed to assess the effect of CYP2C19 polymorphism on warfarin dosage requirements and bleeding complications in the Korean population. Patients were placed into one of four groups according to the dose of warfarin they received and the presence of bleeding complications: regular dose control, regular dose bleeding, low dose control, and low dose bleeding. Genotyping for CYP2C19*2 and CYP2C19*3 was performed by the restriction fragment length polymorphism method for each patient and each study group. The measured internal normalized ratio (INR) in each dose group was similar even though the administered dosage was significantly different. A total of 66 patients were evaluated for CYP2C19 polymorphism. Among them 25 patients (37.9%) were homozygous wild type. Four patients (6.1%) had heterozygous mutations at both loci. Others had mutations on either the CYP2C19*2 or *3 locus. Higher genetic variation was observed in CYP2C19*2 than in CYP2C19*3 among Korean patients on warfarin therapy. Our data suggested that there is a higher incidence of bleeding complications in patients who have a higher allele frequency of CYP2C19. It was also revealed that the distribution of CYP2C19 polymorphism among Asian populations is more similar than of the distribution among Caucasian populations.

Percutaneous Arterial Embolization in the Management of Rectus Sheath Hematoma

OBJECTIVE

Spontaneous rectus sheath hematoma can become clinically relevant and necessitate hemostatic intervention. The aim of this study was to describe the efficacy of percutaneous arterial embolization in the management of this condition.

CONCLUSION

Selective transcatheter embolization is effective hemostatic treatment of patients with large, clinically relevant rectus sheath hematoma.

Thromboembolic Therapies in Dogs and Cats: An Evidence-Based Approach

In veterinary medicine, we are forced to make use of less than ideal "evidence," such as extrapolation from experimental studies in dogs and cats without naturally occurring diseases and from clinical trials in other species (particularly human clinical trials), as well as limited information gained from veterinary clinical experience, small clinical trials, case studies, and anecdotal reports. In this article, specific treatment recommendations are made for each of the common thromboembolic conditions seen in dogs and cats. These recommendations are made with the important caveat that, to date, such suggested therapeutic approaches are based on limited evidence.

Quantity and quality of potential drug interactions with coumarin anticoagulants in the Netherlands

OBJECTIVE

Coumarin anticoagulants are prone to potentially life-threatening drug-drug interactions due to a combination of unfavorable properties. However, real life data on the actual occurrence are scarce. The aim of this study was to quantify and qualify potential drug interactions with coumarin anticoagulants in daily practice.

METHODS

A cohort study including all users of phenprocoumon or acenocoumarol during the period 1991-2003 in the PHARMO Record Linkage System. All 24 individual drugs and 11 drug groups interacting with coumarins according to central database used in the Dutch pharmacies were considered.

MAIN OUTCOME MEASURE

Frequency and type of potential drug interactions during anticoagulant therapy with coumarins.

RESULTS

48,627 out of 76,455 mainly acenocoumarol-users (64%) were dispensed at least one potentially interacting drug (PID) during anticoagulant therapy. About 35% of these cases were dispensed a (very) strongly interacting drug, whereas 3% were dispensed a contraindicated drug. Antibacterial drugs and NSAIDs (39% and 37% of all users, respectively) were the most frequently dispensed PIDs.

CONCLUSION

Potential drug interactions with coumarins frequently occur in daily practice, confronting two-thirds of patients with an increased risk of bleeding. To a large part, this is attributable to commonly prescribed medication like antibacterial drugs and NSAIDs. This situation substantiates the need for proper monitoring or new anticoagulants with less drug-drug interactions.

Recent advances in the treatment of thromboembolic diseases: Venous thromboembolism

Venous thromboembolic diseases are the major concern of rising cost of healthcare and are commonest health problem across the globe. Both genetic and acquired risk factors are believed to be strongly linked with these diseases. Commonly encountered problems to the therapy include dose fixing and routine monitoring, yet some serious problems of bleeding also necessitate the immediate need to develop new agents. The review is primarily concerned with the new developments in the treatment of thromboembolic diseases. Therapeutic applications of anticoagulants, antiplatelets, and thrombolytics have been discussed in enough detail.