American Heart Association/American College of Cardiology Foundation guide to warfarin therapy

Stroke prevention in atrial fibrillation: current status and near-future directions

Prevention of atrial fibrillation-related stroke is an important part of atrial fibrillation management. However, stroke risk is not homogeneous and varies with associated morbidities and risk factors. Risk stratification schemes have been developed that categorize patients' stroke risk into classes based on a combination of risk factors. According to the calculated level of risk, guidelines recommend patients with atrial fibrillation receive antithrombotic therapy either as a vitamin K antagonist or aspirin. Despite recommendations, however, many patients with atrial fibrillation do not receive adequate thromboprophylaxis. We will discuss some of the underlying reasons, in part related to the drawbacks associated with vitamin K antagonists. These highlight the need for new anticoagulants in atrial fibrillation. The novel oral anticoagulants in development may overcome some of the limitations of vitamin K antagonists and address their underuse and safety concerns.

Warfarin anticoagulation: a survey of patients' knowledge of their treatment

INTRODUCTION

Warfarin is used for the treatment of thromboembolic disease. It requires careful and sustained monitoring due to its narrow therapeutic index and potentially life-threatening complications. Patient education and knowledge is, therefore, vital.

AIMS

To assess, in a specialised anticoagulation clinic, the extent of patients' knowledge of their warfarin treatment.

METHODS

Ethical approval was obtained. All patients, aged over 18 years, attending our anticoagulation clinic during our study period were asked to participate.

RESULTS

We enrolled 181 patients, 47.9% of respondents were unaware of any potential drug interactions, 57.7% of patients were unaware of any potential side effects, 20% of patients had experienced side effects, 10.9% of patients had been hospitalised due to side effects, 58% of which were due to Haemorrhage and 79% of patients kept a personal record of their INR.

CONCLUSIONS

Patients' understanding of warfarin treatment was poor, despite their high level of compliance.

Warfarin drug interactions: a comparative evaluation of the lists provided by five information sources

PURPOSE

Detecting potential drug interactions can lead to early interventions that protect patients from serious drug-related problems. The aim of this study was to evaluate the agreement among the lists of warfarin interactions provided by five information sources.

METHODS

The lists of warfarin interactions and the corresponding severity ratings and documentation levels presented by the three compendia and by the World Health Organization (WHO) Model Formulary were all compared, and each list was compared to that provided on the package insert of Marevan, a brand of warfarin. The compendia used were: Drug Interaction Facts, Drug Interactions: Analysis and Management and DRUG-REAX. A kappa coefficient was used to calculate the agreement among the sources.

RESULTS

A total of 537 interactions were listed. Only 13 (2.4%) were common to the five sources. The global Fleiss' kappa coefficient was -0.0080, which indicated poor agreement. Eleven warfarin interactions appeared only in the Marevan package insert. Importantly, 243 interactions (45.3% of the total) were deemed significant in at least one compendium. Only two warfarin interactions were reported as critical by all three compendia and by WHO. The most critical interactions cited by the compendia were missing from the package insert.

CONCLUSIONS

Poor agreement was found among five sources listing warfarin interactions. Potentially severe clinical consequences might occur due to these discrepant recommendations. Finally, the lack of standard terminology and clinical guidance, as well as the possible inaccuracy of severity ratings and documentation might contribute to heterogeneous procedures in clinical practice.

Antithrombotic medication for cardioembolic stroke prevention

Embolism of cardiac origin accounts for about 20% of ischemic strokes. Nonvalvular atrial fibrillation is the most frequent cause of cardioembolic stroke. Approximately 1% of population is affected by atrial fibrillation, and its prevalence is growing with ageing in the modern world. Strokes due to cardioembolism are in general severe and prone to early recurrence and have a higher long-term risk of recurrence and mortality. Despite its enormous preventive potential, continuous oral anticoagulation is prescribed for less than half of patients with atrial fibrillation who have risk factors for cardioembolism and no contraindications for anticoagulation. Available evidence does not support routine immediate anticoagulation of acute cardioembolic stroke. Anticoagulation therapy's associated risk of hemorrhage and monitoring requirements have encouraged the investigation of alternative therapies for individuals with atrial fibrillation. New anticoagulants being tested for prevention of stroke are low-molecular-weight heparins (LMWH), unfractionated heparin, factor Xa inhibitors, or direct thrombin inhibitors like dabigatran etexilate and rivaroxaban. The later exhibit stable pharmacokinetics obviating the need for coagulation monitoring or dose titration, and they lack clinically significant food or drug interaction. Moreover, they offer another potential that includes fixed dosing, oral administration, and rapid onset of action. There are several concerns regarding potential harm, including an increased risk for hepatotoxicity, clinically significant bleeding, and acute coronary events. Therefore, additional trials and postmarketing surveillance will be needed.

Acute neurological issues in pregnancy and the peripartum

Acute neurological diseases requiring hospitalization are relatively rare in women of childbearing age. However, during pregnancy and the postpartum period, several diseases increase in prevalence. Some are unique to the pregnant/postpartum state including preeclampsia and delivery-associated neuropathies. Others, although indirectly related to pregnancy, such as cerebral venous thrombosis, ischemic stroke, and intracerebral hemorrhage, increase in frequency and carry considerable risk of morbidity and mortality. In addition, treatment options are often limited. This review discusses the diseases more commonly seen during pregnancy and the postpartum period, with a focus on emergent neurological diseases and their management. Interventional therapies will also be discussed.

Empiric warfarin dose adjustment with prednisone therapy. A randomized, controlled trial

Typically, the international normalized ratio (INR) is monitored and warfarin dose adjusted, if necessary, to correct non-therapeutic INR after interacting medications, like prednisone, are initiated during warfarin therapy. Preemptively adjusting the warfarin dose is another approach. To evaluate the utility of preemptive warfarin dosage adjustment for preventing non-therapeutic INR following prednisone-warfarin co-administration. Patients were randomized to either a preemptive warfarin dose reduction between 10 and 20% (intervention) or reactive warfarin dose adjustment (control) within 72 h of warfarin-prednisone co-administration. Subjects received a follow-up INR within 7 days. Primary outcome was the occurrence of follow-up INR ≥ 1 point over the INR goal range upper limit. Secondary outcomes included INR control, purchases of prescription vitamin K, and warfarin-associated adverse events in the 30 days after prednisone initiation. Twenty and 17 patients comprised the intervention and control groups. The intervention group's warfarin dose was reduced by a median of 11.8%. More control patients (n = 5) experienced an INR ≥ 1 point over the INR goal range upper limit compared to intervention (n = 2); however, the actual difference (29.4 vs.10.0%) was not statistically significant (P = 0.21). A higher percentage of intervention patients had a subtherapeutic follow-up INR compared to control (40 vs. 5.9%, P = 0.02). One patient from each group experienced warfarin-associated bleeding. No thromboembolic complications or vitamin K purchases were observed. For patients initiating prednisone therapy, preemptive warfarin dose reduction resulted in a non-significant reduction in supratherapeutic INR but increased the likelihood of subtherapeutic INR compared to INR monitoring with reactive warfarin dose adjustment.

Optimizing use of current anticoagulants

Although warfarin has been the mainstay of oral anticoagulation therapy for decades, evidence-based methods for improving the quality of warfarin therapy remain underused. The arrival of new anticoagulants that do not require routine laboratory monitoring and lack the significant dietary and drug interaction potential that are seen with warfarin is an important evolutionary step in the management of thromboembolic disease. However, it will be years before the efficacy and long-term safety of these new agents are defined. Newer oral anticoagulants will be more expensive than generic warfarin. This article examines various approaches to optimize the clinical use of warfarin. For patients able to achieve stable anticoagulation control, warfarin remains an important therapeutic option, delivering similar clinical outcomes at a fraction of the cost to the health care system.

Comparative performance of gene-based warfarin dosing algorithms in a multiethnic population

SUMMARY BACKGROUND

Gene-based warfarin dosing algorithms have largely been developed in homogeneous populations, and their generalizability has not been established.

OBJECTIVES

We sought to assess the performance of published algorithms in a racially diverse and multiethnic sample, and determine if additional clinical variables or genetic variants associated with dose could enhance algorithm performance.

PATIENTS AND METHODS

In 145 compliant patients on warfarin with a goal international normalized ratio (INR) of 2-3, stable, therapeutic doses were compared with predicted doses using 12 reported algorithms that incorporated CYP2C9 and VKORC1 variants. Additional covariates tested with each model included race, concurrent medications, medications known to interact with warfarin and previously described CYP4F2, CALU and GGCX variants.

RESULTS

The mean patient age was 67 +/- 14 years; 90 (62%) were male. Eighty-two (57%) were Caucasian, 28 (19%) African-American, 20 (14%) Hispanic and 15 (10%) Asian. The median warfarin dose was 35 mg per week (interquartile range 23-53 mg per week). Gene-based dosing algorithms explained 37-55% of the variation in warfarin dose requirements. Neither the addition of race, number of concurrent medications nor the number of concurrent medications interacting with warfarin enhanced algorithm performance. Similarly, consideration of CYP4F2, CALU or GGCX variant genotypes did not improve algorithms.

CONCLUSIONS

Existing gene-based dosing algorithms explained between approximately one-third and one-half of the variability in warfarin dose requirements in this racially and ethnically diverse cohort. Additional clinical and recently described genetic variants associated with warfarin dose did not enhance prediction in our patient population.

Effect of anticoagulant and antiplatelet therapy in patients with spontaneous intra-cerebral hemorrhage: Does medication use predict worse outcome?

OBJECTIVES

To assess the impact of anticoagulants and antiplatelet agents on the severity and outcome of spontaneous non-traumatic intra-cerebral hemorrhage (ICH). To evaluate associations between reversal of anticoagulation and mortality/morbidity in these patients.

METHODS

Data was collected on a consecutive cohort of adults presenting with ICH to an academic Emergency Department over a 3-year period starting January 2006.

RESULTS

The final cohort of 245 patients consisted of 125 females (51.1%). The median age of the cohort was 73 years [inter-quartile (IQR) range of 59-82 years]. Antiplatelet (AP) use was seen in 32.6%, 18.4% were using anticoagulant (AC) and 8.9% patients were on both drugs (AC+AP). Patients on AC had significantly higher INR (median 2.3) and aPTT (median 31 s) when compared to patients not on AP/AC (median INR 1.0, median aPTT 24s; p<0.001). Similarly patients on AC+AP also had higher INR (median 1.9) and aPTT (median 30s) when compared to those not on AC/AP (p<0.001). Hemorrhage volumes were significantly higher for patients on AC alone (median 64.7 cm(3)) when compared to those not on either AC/AP (median 27.2 cm(3); p=0.05). The same was not found for patients using AP (median volume 20.5 cm(3); p=0.813), or both AC+AP (median volume 27.7 cm(3); p=0.619). Patients on AC were 1.43 times higher at risk to have intra-ventricular extension of hemorrhage (IVE) as compared to patients not on AC/AP (95% CI 1.04-1.98; p=0.035). There was no relationship between the use of AC/AP/AC+AP and functional outcome of patients. Patients on AC were 1.74 times more likely to die within 7 days (95% CI 1.0-3.03; p=0.05). No relationship was found between use of AP or AC+AP use and mortality. Of the 82 patients with INR>1.0, 52 patients were given reversal (minimum INR 1.4, median 2.3). Therapy was heterogeneous, with fresh frozen plasma (FFP) being the most commonly used agent (86.5% patients, median dose 4U). Vitamin K, activated factor VIIa and platelets were the other agents used. Post reversal, INR normalized within 24h (median 1.2, IQR 1.1-1.3). There was no association between reversal and volume of hemorrhage, IVE, early mortality (death<7 days) or functional outcome.

CONCLUSIONS

Anticoagulated patients were at 1.7 times higher risk of early mortality after ICH. Reversal of INR to normal did not influence mortality or functional outcome.

Prothrombin complex concentrate in surgical patients: retrospective evaluation of vitamin K antagonist reversal and treatment of severe bleeding

Introduction

Prothrombin complex concentrates are recommended for rapid reversal of vitamin K anticoagulants. As they normalize levels of vitamin K dependent clotting factors and re-establish hemostasis, they may also be used as adjunctive therapy in patients with major bleeding. The aim of this study was to retrospectively evaluate the efficacy of prothrombin complex concentrates in the surgical setting.

Methods

The case notes of 50 patients requiring urgent oral anticoagulation reversal (n = 12) or with severe perioperative coagulopathic bleeding (n = 38) who received an infusion of prothrombin complex concentrate (Beriplex P/N(R) 500) at the surgical department of the University of Munich Hospital, Germany were retrospectively reviewed. Efficacy of prothrombin complex concentrate application was evaluated using the Quick test, reported as an international normalized ratio, hemodynamic measurements and requirement for blood products. Safety assessments included whole blood hemoglobin levels and specific parameters of organ dysfunction.

Results

Baseline characteristics were comparable, except that mean baseline international normalized ratio and hemoglobin levels were significantly higher (P < 0.01) in anticoagulation reversal than in bleeding patients. In anticoagulation reversal, the international normalized ratio was significantly reduced (from 2.8 +/- 0.2 at baseline to 1.5 +/- 0.1, P < 0.001) after one prothrombin complex concentrate infusion (median dose 1500 IU; lower quartile 1,000, upper quartile 2,000). No major bleeding was observed during surgery after prothrombin complex concentrate administration. Only one patient received platelets and red blood cell transfusion after prothrombin complex concentrate administration. In bleeding patients, infusion of prothrombin complex concentrate (median dose 2,000 IU; lower quartile 2,000, upper quartile 3,000) significantly reduced the INR from 1.7 +/- 0.1 at baseline to 1.4 +/- 0.1 (P < 0.001). This decrease was unrelated to fresh frozen plasma or vitamin K administration. Bleeding stopped after prothrombin complex concentrate administration in 4/11 (36%) patients with surgical bleeding and 26/27 (96%) patients with diffuse bleeding. Hemoglobin levels increased significantly from baseline in bleeding patients (P < 0.05) and mean arterial pressure stabilized (P < 0.05). No thrombotic events or changes in organ function were reported in any patient.

Conclusions

Prothrombin complex concentrate application effectively reduced international normalized ratios in anticoagulation reversal, allowing surgical procedures and interventions without major bleeding. In bleeding patients, the improvement in coagulation after prothrombin complex concentrate administration was judged to be clinically significant.

How much does international normalized ratio monitoring cost during oral anticoagulation with a vitamin K antagonist? A systematic review

Next-generation oral anticoagulants offer the potential for effective prevention and treatment of thrombosis without the need for repeated monitoring of the international normalized ratio (INR). This systematic review evaluated the costs associated with INR monitoring tests performed as part of the standard management of oral anticoagulation with vitamin K antagonists. Studies published in or after 1990 reporting the costs of INR monitoring were identified from bibliographic databases and manual searches of reference lists. Cost data were extracted and inflated to the year 2006 before purchasing power parity conversion to US dollars. A total of 29 studies reported the cost of one INR test, which was shown to range from $6.19 to $145.70. Cost estimates were based on various combinations of direct medical costs, such as healthcare contacts, equipment, laboratory tests, clerical costs (postage and stationery), telephone calls, quality control, training/education and patient transportation, and indirect costs, such as time lost from work. In conclusion, the cost of INR monitoring varied substantially between studies depending on the monitoring modality and setting, and the cost categories included. When selecting a published estimate, healthcare decision makers should ensure that the chosen estimate reflects local service provision as closely as possible.

Pharmacogenetics in cardiovascular antithrombotic therapy

Thrombosis is the most important underlying mechanism of coronary artery disease and embolic stroke. Hence, antithrombotic therapy is widely used in these scenarios. However, not all patients achieve the same degree of benefit from antithrombotic agents, and a considerable number of treated patients will continue to experience a new thrombotic event. Such lack of clinical benefit may be related to a wide variability of responses to antithrombotic treatment among individuals (i.e., interindividual heterogeneity). Several factors have been identified in this interindividual heterogeneity in response to antithrombotic treatment. Pharmacogenetics has emerged as a field that identifies specific gene variants able to explain the variability in patient response to a given drug. Polymorphisms affecting the disposition, metabolism, transporters, or targets of a drug all can be implicated in the modification of an individual's antithrombotic drug response and therefore the safety and efficacy of the aforementioned drug. The present paper reviews the modulating role of different polymorphisms on individuals' responses to antithrombotic drugs commonly used in clinical practice.

Searching for 'omic' biomarkers

Cardiovascular diseases impose enormous social and economic burdens on both individual citizens and on society as a whole. Clinical indicators such as high blood pressure, blood cholesterol and obesity have had some utility in identifying those who are at increased risk of cardiovascular events. However, there remains an urgent need for sensitive and specific indicators, preferably acquired through minimally invasive means, to help stratify patients for more personalized health care. As such, there has been a steadily growing interest in searching for 'omic' biomarkers of cardiovascular diseases. Historically, the transition of cardiac biomarker discovery to implementation has been a lengthy and somewhat unregulated process. Recent technological advancements, as well as concurrent efforts by regulatory agencies such as the Food and Drug Administration (United States) and Health Canada to establish policies and guidelines in the 'omic' arena, have helped propel the discovery and validation of biomarkers forward. The present paper provides perspective on current strategies in the biomarker development pathway, as well as the potential limitations associated with each step from discovery to clinical uptake. Canadian biomarker studies now underway illustrate the possibilities for assessment of risk, diagnosis, prognosis and response to therapy, and for the drug discovery process.

INR variability in atrial fibrillation: a risk model for cerebrovascular events

BACKGROUND

Use of vitamin K antagonists (VKAs) for stroke prophylaxis in patients with non-valvular atrial fibrillation (NVAF) necessitates frequent monitoring of the international normalized ratio (INR) to avoid the increased risk of hemorrhage associated with excess anticoagulation, or ischemic stroke due to insufficient anticoagulation. We therefore developed a model to estimate the excess morbidity attributable to inadequate INR control in NVAF populations.

METHODS

Equations expressing the risk of cerebrovascular events as a function of INR were generated using published data. Additional functions were developed to estimate the excess risk attributable to inferior INR control, using the clinical trial setting as the reference.

RESULTS

The derived risk functions were applied to French NVAF patients receiving anticoagulation in routine medical practice. This population achieved a time in therapeutic range (INR 2.0-3.0) of 59%, compared with 68% time in therapeutic range (TTR) in the SPORTIF III and V clinical trials. However, there was considerable variation in the TTR among patients in routine care, of whom 36% were in range for less than 50% of the time. Among this latter group, the relative risk, compared with the clinical trial setting, was 1.47 for ischemic stroke and 2.68 for intracranial hemorrhage. Conversely, for patients achieving a TTR greater than 50%, the relative risks for ischemic stroke and intracranial hemorrhage were 0.99 and 1.16, respectively.

CONCLUSIONS

This model permits estimation of the excess risk attributable to inferior INR control in NVAF populations receiving VKA anticoagulation, and has implications for public health planning and management.

The clinical content of preconception care: women with chronic medical conditions

This article reviews the medical conditions that are associated with adverse pregnancy outcomes for women and their offspring. We also present the degree to which specific preconception interventions and treatments can impact the effects of the condition on birth outcomes. Because avoiding, delaying, or achieving optimal timing of a pregnancy is often an important component of the preconception care of women with medical conditions, contraceptive considerations particular to the medical conditions are also presented.

The clinical content of preconception care: the use of medications and supplements among women of reproductive age

The use of prescription and over-the-counter medications and dietary supplements are common among women of reproductive age. For medications, little information about the teratogenic risks or safety is available, as pregnant women are traditionally excluded from clinical trials, and premarketing animal studies do not necessarily predict the effects of treatment in human pregnancy. Even less is typically known about the effects of dietary supplements on pregnancy outcomes, as they are not held to the same rigorous safety and efficacy standards as prescription medications. Congenital anomalies associated with medication use are potentially preventable, because they are linked with modifiable maternal exposures during the period of organogenesis. However, as women of reproductive age experience acute and chronic conditions that can result in adverse outcomes for the woman and her offspring, the benefits of use of a particular medication before or early in pregnancy may outweigh the risks. Resources and principles outlined in this article will aid healthcare providers in selecting appropriate medication regimens for women of reproductive age, particularly those with chronic health conditions, those who are planning a pregnancy, and those who may become pregnant.

Utility of an international normalized ratio testing device in a hospital-based dental practice

OBJECTIVES

The authors aimed to evaluate the utility of an in-office international normalized ratio (INR) testing device in identifying patients with INR test values considered out of the normal range for dental procedures.

METHODS

This prospective cohort study involved use of an INR testing device to obtain INR test values in the dental office for patients thought to be at risk of experiencing bleeding complications after undergoing invasive dental procedures. The authors recorded demographic, social and medical history data, as well as clinical signs and symptoms of liver disease. The authors considered an INR out of range if it was greater than or equal to 1.4 for patients with potential liver disease and greater than 3.5 for patients receiving warfarin.

RESULTS

The authors completed an in-office INR test for 66 patients receiving warfarin whose INR had not been tested within the preceding 48 hours and 34 patients suspected of having liver disease. Eleven (17 percent) patients receiving warfarin and seven (21 percent) patients suspected of having liver disease had INR values considered out of range. Dental treatment was deferred for eight of 11 patients in the warfarin group who had INR values in the range of 3.6 to 7.4, while three others had dental procedures without bleeding complications. Six of seven patients who had documented or suspected liver disease and an out-of-range INR (range 1.5-2.5) underwent their dental procedures without experiencing bleeding complications.

CONCLUSIONS

Use of an in-office INR test indicated a high incidence of elevated INR values. The results of this study point to the importance of obtaining current INR values before performing invasive dental procedures for patients receiving warfarin therapy whose INR values have not been tested recently, and for patients thought to be at risk of developing or having liver disease.

Warfarin with fluoroquinolones, sulfonamides, or azole antifungals: interactions and the risk of hospitalization for gastrointestinal bleeding

The aim of this study was to determine whether a potential pharmacokinetic interaction between warfarin and orally administered anti-infectives increases the risk of hospitalization for gastrointestinal (GI) bleeding in warfarin users. We conducted a nested case-control and case-crossover study using US Medicaid data. Logistic regression was used to determine the association between GI bleeding and prior use of ciprofloxacin, levofloxacin, gatifloxacin, co-trimoxazole, or fluconazole vs. no exposure and also vs. use of cephalexin, which would not be expected to interact with warfarin. All of the anti-infectives examined were associated with elevated odds ratios (ORs) when compared to no exposure to these drugs. With cephalexin data as the reference, the ORs for co-trimoxazole (OR: 1.68 (95% confidence interval (CI): 1.21-2.33) in the prior 6-10 days) and fluconazole (OR: 2.09 (95% CI: 1.34-3.26) in the prior 11-15 days) were significantly elevated. Warfarin users who had received an anti-infective agent showed a substantially increased risk of GI bleeding. However, a drug-drug interaction with warfarin was evident only for co-trimoxazole and fluconazole.

Choice of echocardiography method for postoperative evaluation of mitral valve replacement with a mechanical prosthesis

OBJECT

The French Cardiology Society (SFC) systematically recommends (Class I) transesophageal echocardiography (TEE) after any mitral valve replacement with a mechanical prosthesis (MMVR). Taking into account the increasing workload of echocardiography laboratories, our attitude was to propose that only post-operative transthoracic echocardiography (TTE) is performed. The purpose of this study was to evaluate the possible risks of this simplified procedure.

METHODS

We performed a precise analysis of one full year of practice of MMVR with exhaustive follow-up for the first 2 years concentrating on thromboembolic complications.

RESULTS

From January to December 2003, 84 MMVRs (46 after rheumatic fever, 22 degenerative disease, 11 infective endocarditis (IE) and 5 ischemia) were conducted in 45 women and 39 men of average age 61 years. Early mortality (<30 days) concerned 5 patients (5.9%). A control TTE to determine normal prosthetic function was performed 7+/-2 days after surgery and this revealed 2 cases of nonobstructive thrombosis which were treated medically, 3 cases of paraprosthetic regurgitation, and 1 vegetation due to underlying IE. Actuarial survival was 90.5% at 1 year and 83.3% at 2 years. After a mean follow-up of 179.3 patient-years, 5 patients were reoperated (5.9%): 1 for IE, 1 for paravalvular regurgitation, 1 for mitral valve insufficiency with haemolysis, and 2 for obstructive prosthetic valve thromboses. In addition there were 2 cases of prosthetic valve thrombosis, 8 ischemic strokes (2 ministrokes, 6 sequelar strokes), and 1 peripheral embolism. The global thromboembolic complication rate was therefore 6.1 per 100 patient-years (n=11). There were 4 hemorrhagic events, i.e. a rate of 2.2 events per 100 patient-years. 63% of the 1193 INR conducted were within the target range (3-4.5), 26% were below 3 and 11% were greater than 4.5. 35% of patients with thromboembolic complications had an INR<3.

CONCLUSION

Morbidity and mortality during the first 2 years after MMVR were relatively high but equivalent to the values of comparable series in the literature. These complications would not have been reduced by a more precise screening based on early TEE. Despite the increasingly litigious nature of the doctor-patient relationship, it would probably be excessive to oppose that this guideline was not followed in a dispute; in particular as it is difficult to apply this measure as echocardiography departments are overworked.

Pharmacogenetics in critical care: atrial fibrillation as an exemplar

Pharmacogenetic testing is currently not routine in critical care settings but recent changes in the warfarin label are likely to lead to critical care nurses encountering physician or nurse practitioner orders for such testing. Although the science for pharmacogenetics is complex, the components of patient teaching are not beyond that which nurses already provide about other laboratory, disease, and treatment-based information. It is reasonable to expect that as the science of pharmacogenetics and pharmacogenomics expands and discoveries are translated in clinical settings, the additional information from pharmacogenetic test results will help prescribers select or adjust medication doses to reduce the risk for adverse drug reactions and improve the chances of achieving therapeutic targets in a timely fashion.

[Short- and long-term results of mitral valve replacement by caged-ball and bileaflet mechanical prosthesis (series of 236 consecutive patients with average follow-up of 11 years)]

OBJECTIVES

To study the early and late results of mitral valve replacement (MVR) by Starr-Edwards caged-ball and bileaflet mechanical prosthesis.

MATERIAL AND METHODS

We retrospectively analyzed 236 MVR performed in 236 patients: 127 by Starr-Edwards prosthesis (group 1) and 109 by bileaflet prosthesis (group 2).

RESULTS

During the early period (30 days), the mortality rate was higher in group 1 (6.3% vs 1.8%; p=0.0001), while hemorrhagic, thromboembolic and infectious complications were comparable in the two groups. In the late period (>30 days) and with an average follow-up of 11.5+/-5.7 years, mortality was higher in group 1 (9.4% vs 4.6%; p<0.0001). The same was true for thromboembolic complications (20.8% vs 6.4%; p<0.0001), hemorrhagic complications (13.4% vs 7.3%; p=0.02), infectious complications (3.1% vs 0.9%; p=0.02) and cardiac complications that were not due to the prosthesis (32.3% vs 14.7 %; p=0.02). The hemodynamic profile of the bileaflet prostheses was better than that of the Starr-Edwards prostheses (average functional prosthetic surface area was 2.37+/-0.44 cm(2) and average pressure gradient was 5.6+/-1.1 mmHg vs 2.04+/-0.52 cm(2) and 7.6+/-4.9 mmHg).

CONCLUSION

Our work confirms the superiority of bileaflet mechanical prostheses, with rates of early and late mortality, thromboembolic and hemorrhagic complications lower than those of the Starr-Edwards prostheses in more than 11 years of follow-up. However, one should not forget that the prevention of infective endocarditis, good observance of oral anticoagulant treatment and early surgery before left ventricular dysfunction occurs remain the best guarantee a good result of the MVR.

Genetic variations and their influence on risk and treatment of venous thrombosis

Venous thrombosis (VT) is a highly prevalent disease. Risk factors can be genetic or acquired. The well-established genetic polymorphisms predisposing to thrombophilic disorders can be divided into rare 'loss-of-function mutations' in anticoagulant proteins and common 'gain-of-function mutations' in procoagulant proteins, which are weaker risk factors. In addition to functional polymorphisms, defects in common pathways affecting biosynthesis or clearance of plasma coagulation factors and their relations to VT risk have been detected. Recently, investigations regarding genetic variations and response to drug treatment, relevant for the pathogenesis as well as therapy of venous thromboembolism have been performed. The methodical advances in genetic research have led to the identification of a number of new variants with still unclear association to VT. This review aims to discuss the established genetic risk factors as well as some candidate predictors of VT. Further, the recent developments in pharmacogenomics are reviewed.

Periprocedural anticoagulation management of patients with nonvalvular atrial fibrillation

OBJECTIVE

To estimate the 3-month cumulative incidence of thromboembolism (TE), bleeding, and death among consecutive patients with nonvalvular atrial fibrillation (AF) who were receiving long-term anticoagulation therapy and were referred to the Thrombophilia Center at Mayo Clinic for periprocedural anticoagulation management.

PATIENTS AND METHODS

In a prospective cohort study of consecutive patients receiving long-term anticoagulation therapy who were referred to the Thrombophilia Center for periprocedural anticoagulation management over the 7-year period, January 1, 1997, to December 31, 2003, 345 patients with nonvalvular AF were eligible for inclusion. Warfarin was stopped 4 to 5 days before and was restarted after surgery as soon as hemostasis was assured. The decision to provide bridging therapy with heparin was individualized and based on the estimated risks of TE and bleeding.

RESULTS

The 345 patients with AF (mean +/- SD age, 74+/-9 years; 33% women) underwent 386 procedures. Warfarin administration was not interrupted for 44 procedures. Periprocedural heparin was provided for 204 procedures. Patients receiving heparin were more likely to have prior TE (43% vs 24%; P<.001) and a higher CHADS2 (congestive heart failure, hypertension, age, diabetes, stroke) score (2.2 vs 1.9; P=.06). Four patients had 6 episodes of TE (3 strokes and 3 acute coronary episodes; TE rate, 1.1%; 95% confidence interval, 0.0%-2.1%). Nine patients had 10 major bleeding events (major bleeding rate, 2.7%; 95% confidence interval, 1.0%-4.4%). There were no deaths. Neither bleeding nor TE rates differed by anticoagulant management strategy.

CONCLUSION

The 3-month cumulative incidence of TE and bleeding among patients with AF in whom anticoagulation was temporarily interrupted for an invasive procedure was low and was not significantly influenced by bridging therapy.

Management of warfarin-related intracerebral hemorrhage

Warfarin-related intracerebral hemorrhage (WICH) is a medical and neurosurgical emergency with a 1-month mortality of approximately 50%. Warfarin is commonly is used in patients with atrial fibrillation to prevent ischemic stroke and to prevent progression of deep vein thrombosis to pulmonary embolism. Owing to the ageing population, and increased incidence of atrial fibrillation with age and warfarin use, the incidence of WICH is expected to rise in the future. When WICH occurs, immediate discontinuation of warfarin with rapid warfarin reversal remains the first-line intervention, often with neurosurgical intervention. The optimal agent for rapid warfarin anticoagulation reversal remains to be defined owing to the lack of prospective randomized trials. We review current literature and prospects for future research for this devastating neurologic emergency.

[Venous thromboembolism associated with long-term use of central venous catheters in cancer patients]

Increased incidence of cancers and the development of totally implanted venous access devices that contain their own port to deliver chemotherapy will lead to a greater than before numbers of central venous catheter-related thrombosis (CVCT). Medical consequences include catheter dysfunction and pulmonary embolism. Vessel injury caused by the procedure of CVC insertion is the most important risk factor for development of CVCT. This event could cause the formation of a fresh thrombus, which is reversible in the large majority of patients. In some cases, thrombus formation is not related to catheter insertion. The incidence of CVC-related DVT assessed by venography has been reported to vary from 30 to 60% but catheter-related DVT in adult patients is symptomatic in only 5% of cases. The majority of patients with CVC-related DVT is asymptomatic or has nonspecific symptoms: arm or neck swelling or pain, distal paresthesias, headache, congestion of subcutaneous collateral veins. In the case of clinical suspicion of CVC-related deep venous thrombosis (DVT), compressive ultrasonography (US), especially with doppler and color imaging, currently is first used to confirm the diagnosis. Consequently, contrast venography is reserved for clinical trials and difficult diagnostic situations. There is no consensus on the optimal management of patients with CVC-related DVT. Treatment of CVC-related VTE requires a five- to seven-day course of adjusted-dose unfractionated heparin or low molecular weight heparin (LMWH) followed by oral anticoagulants. Long-term LMWH that has been shown to be more effective than oral anticoagulant in cancer patients with lower limb DVT, could be used in these patients. The efficacy and safety of pharmacologic prophylaxis for CVC related thrombosis is not established and the last recommendations suggest that clinicians not routinely use prophylaxis to try to prevent thrombosis related to long-term indwelling CVCs in cancer patients. Additional studies performed in high risk populations with appropriate dosage and timing will help to define which patients could benefit from prophylaxis.

Pregnancy and adult congenital heart disease

Increasing numbers of women with complex congenital heart disease are reaching childbearing age. Pregnancy is a major issue in the management of adult congenital heart disease. Cardiac disease is one of the most common causes of maternal morbidity and mortality. Complications, such as growth retardation, preterm and premature birth and even fetal and neonatal mortality, are more frequent among children of women with congenital heart disease. The risk of complications is determined by the severity of the cardiac lesion, the presence of cyanosis, the maternal functional class and the use of anticoagulation. However, the pathophysiology of these complications is not completely understood and may be related to a diminished increase in cardiac output and/or endothelial dysfunction. The management of pregnant cardiac patients is based on limited clinical information. This article reviews pre-pregnancy counseling and management during pregnancy in patients with congenital heart disease.

Discharge antithrombotic strategies among patients with acute coronary syndrome previously on warfarin anticoagulation: physician practice in the CRUSADE registry

BACKGROUND

Patients experiencing acute coronary syndromes (ACS) with high-risk features frequently undergo percutaneous coronary intervention (PCI) with stent placement, prompting the requisite administration of aspirin and clopidogrel. The current management of ACS patients with a concomitant indication for warfarin anticoagulant therapy is a question of growing interest and clinical relevance.

METHODS

We analyzed discharge antithrombotic medication use among all patients with non-ST-segment elevation (NSTE) ACS enrolled in the Can Rapid risk stratification of Unstable angina patients Suppress ADverse outcomes with Early implementation of the ACC/AHA Guidelines (CRUSADE) initiative who were receiving warfarin at the time of hospital admission. Multivariable logistic regression was used to determine factors associated with a decision to discontinue warfarin at discharge.

RESULTS

Among 5673 patients with ACS previously on home warfarin, 1357 (24%) were not discharged on warfarin. In the subset of 1247 patients who underwent coronary stenting, 60% were prescribed triple anticoagulation therapy (aspirin, clopidogrel, and warfarin), 31% were given aspirin and clopidogrel without warfarin, and 3% received warfarin and aspirin without clopidogrel. Factors associated with a decision not to continue warfarin at the time of hospital discharge included in-hospital red blood cell transfusion, non-white race, prior stroke, and discharge clopidogrel use. The decision to continue warfarin at discharge correlated with perceived bleeding risk and was unaffected by patients' stroke risk.

CONCLUSION

Physician practices vary with regard to the perceived optimal antithrombotic strategy at time of hospital discharge among patients with ACS with a concomitant indication for warfarin. Decisions are influenced primarily by other medication use and anticipated bleeding risk. Further research is needed to guide patient care based on the safety and efficacy of antiplatelet-anticoagulant combined pharmacotherapy.

Antithrombotic treatment for patients on oral anticoagulation undergoing coronary stenting

BACKGROUND

Dual antiplatelet treatment with aspirin and a thienopyridine is the antithrombotic treatment recommended after coronary stenting. Such strategy is generally not applicable in most patients with an indication for oral anticoagulation (OAC), for whom however, information about the optimal antithrombotic regimen is currently limited.

METHODS

In order to derive some practical indications for the clinicians who are requested to care for these patients, the available evidence on the use, safety and efficacy of the various antithrombotic strategies was reviewed.

RESULTS

A substantial variability in the choice of treatment was observed in current practice where, however, standardized management protocols are seldom used. Triple therapy with OAC, aspirin and a thienopyridine is the most frequently adopted regimen, although its safety appears suboptimal, due to an apparent increased incidence of major hemorrhagic complications. Conversely, the efficacy of the combination of OAC and aspirin is suboptimal, so that such regimen should be considered only for patients at very high hemorrhagic risk, and in association with the implantation of more "biocompatible" stents.

CONCLUSIONS

While waiting for further studies to generate more consistent evidence, the choice of the antithrombotic treatment for patients with an indication for OAC undergoing coronary stenting should be guided by careful stratification of both thrombotic/thromboembolic and hemorrhagic risks. In general, however, the implantation of drug-eluting stents should be avoided, due to the prolonged need for dual antiplatelet administration, and the radial approach preferred, due to the virtual elimination of bleeding complications at the arterial access site.

Possible Amiodarone−Warfarin Interaction: A Reemphasis on a Potentially Dangerous Drug−Drug Interaction

This article reports two patients with delayed amiodarone— warfarin interaction resulting in a significant elevation in the international normalized ratio. One patient developed episodes of nosebleeds. Amiodarone is a potent inhibitor of the cytochrome P450 enzyme system. Warfarin undergoes metabolism via the same isoenzyme, potentially leading to prolongation of elevated international normalized ratio levels. A decrease in the warfarin dose is thus warranted when coadministered with amiodarone to circumvent the potential danger of this interaction, which can go unnoticed because several weeks of therapy may be necessary to discern an elevated international normalized ratio. The Naranjo probability scale indicated a possible relationship between the elevated international normalized ratio levels and the coadministration of amiodarone and warfarin. With the coadministration of warfarin and amiodarone, frequent and close monitoring of warfarin is paramount, especially in the initial weeks of therapy, in an effort to prevent supratherapeutic international normalized ratios and bleeding complications.

Impact of preemptive warfarin dose reduction on anticoagulation after initiation of trimethoprim-sulfamethoxazole or levofloxacin

BACKGROUND

Antibiotics can potentiate warfarin anticoagulation. While preemptive warfarin dose reduction (DR) upon initiation of antibiotics has been advocated by experts, there are no published data regarding the efficacy of this strategy vs. the conventional strategy of not changing warfarin dose and carefully following international normalized ratio (INR) results.

METHODS AND RESULTS

We compared the efficacy of preemptive 10-20% DR vs. no change in warfarin dosing in 40 chronically anticoagulated patients initiating trimethoprim-sulfamethoxazole (TMP-SMX) or levofloxacin. Eighteen patients received preemptive warfarin DR and 22 control patients underwent no change in warfarin dosing. There was no difference between the DR and control groups in the mean INR before beginning antibiotic therapy (2.53 +/- 0.12 vs. 2.52 +/- 0.11; P > 0.9). Mean interval between initiation of antibiotic and next INR was 5.1 +/- 0.4 vs. 4.7 +/- 0.5 days for DR vs. control patients, respectively (P > 0.5). For both TMP-SMX and levofloxacin, patients managed with a preemptive warfarin DR strategy did not exhibit a statistically significant change in the INR after initiating antibiotic therapy. In contrast, for each antibiotic, control group patients exhibited a significant increase in mean post-antibiotic INR compared to mean pre-antibiotic INR, though the effect was more pronounced in patients treated with TMP-SMX than with levofloxacin. Of DR group patients who were treated with TMP-SMX, none (0/8) developed a subtherapeutic INR, while 40% (4/10) of levofloxacin-treated patients developed a sub-therapeutic INR. Supra-therapeutic INR results led to transient interruption of warfarin dosing in 2 patients (11%) in the DR group vs. 12 patients (55%) in the control group (P = 0.007).

CONCLUSIONS

Prophylactic warfarin DR of 10-20% is effective in maintaining therapeutic anticoagulation in patients initiating TMP-SMX. An expectant strategy consisting of no change in warfarin dosing with short-term INR follow-up appears reasonable in patients treated with levofloxacin.

Effectiveness of Factor IX Complex Concentrate in Reversing Warfarin Associated Coagulopathy for Intracerebral Hemorrhage

INTRODUCTION

The objective of this study is to show the effectiveness of Factor IX complex concentrate (FIXCC) for rapid reversal of an elevated International Normalized Ratio (INR) in patients with anticoagulation-associated intracerebral hemorrhage (AAICH).

METHODS

We, retrospectively, analyzed the clinical data of 19 patients with the diagnosis of AAICH from January 2005 to May 2006. A comparison was made among patients treated with FFP and Vit.K [FFP-group (n = 9)] and patients treated with FIXCC in addition to FFP and Vit.K [FIXCC-group (n = 10)]. INR of 1.4 or less was taken as target.

RESULTS

Mean INR on admission for FFP and FIXCC group was 1.84 +/- 0.31 and 2.44 +/- 1.48, respectively (P = 0.315). After administration of therapy, the INR was reduced from 1.84 +/- 0.31 to 1.34 +/- 0.08 (P < 0.05) in FFP group and 2.44 +/- 1.48 to 1.34 +/- 0.07 (P < 0.005) in FIXCC group. Three patients in FFP group (33%) and 8 patients in FIXCC group (80%) reached their target INR in 3-4 h after initiation of therapy (P = 0.012). Mean time taken by both FFP and FIXCC groups to reach the target INR was 8.52 +/- 5.60 h and 4.25 +/- 2.12 h, respectively (P < 0.05). The mean rate of INR correction was 0.06 +/- 0.03 and 0.27 +/- 0.25 per hour for the FFP and FIXCC group, respectively (P < 0.005). There was one death in FIX group and two in FFP group and no thrombotic complications.

CONCLUSION

Our data suggests that FIXCC in combination with FFP and Vit.K may result in decreased time required when compared to FFP and Vit.K alone for correction of warfarin associated coagulopathy in neurosurgical emergencies.