European Atrial Fibrillation Trial Study Group. Optimal oral anticoagulant therapy in patients with nonrheumatic atrial fibrillation and recent cerebral ischemia

Cardiac Causes of Stroke

At least 20% of all ischemic strokes are cardioembolic. Cardiac conditions that cause cerebral embolism are classified as major or minor depending on whether the causal link has or has not been fully established between the underlying cardiac condition and the stroke. Atrial fibrillation, acute myocardial infarction, valvular heart disease, infective endocarditis, nonbacterial thrombotic endocarditis, and atrial myxoma are the main cardiac causes of cerebral embolism. Patent foramen ovale, atrial septal aneurysm, mitral valve prolapse, mitral annular calcification, calcific aortic stenosis, and mitral valve strands are cardiac conditions with a potential causal link to cerebral embolism, but until now, either they have been found to be poor predictors of recurrent stroke or their risk of recurrent stroke is unknown. The management of patients with a stroke of cardiac source is twofold: 1) treatment of the acute phase of stroke and 2) prophylactic treatment of recurrent thromboembolism. When possible, primary prevention of cerebral embolism should be recommended, particularly in cardiac conditions with known high risk of stroke (eg, atrial fibrillation, mitral stenosis, or presence of mechanical prosthetic heart valves).

Use of oral anticoagulants in older patients

Recently published American and British guidelines have comprehensively reviewed the indications for long term anticoagulation. The best evidence currently available supports the use of long term oral anticoagulants in patients with nonvalvular atrial fibrillation (NVAF), venous thromboembolic disease, ischaemic heart disease, mural thrombi, and mechanical heart valves. Selected patients with valvular heart disease, cerebral vascular disease, and peripheral arterial disease may also benefit from the use of these drugs. When no specific contraindications are present, elderly patients with either paroxysmal or persistent NVAF should be considered candidates for treatment with anticoagulants. Pooled analyses of the results from 9 randomised trials demonstrate that warfarin significantly reduces the risk of ischaemic stroke in patients with NVAF, particularly those in a 'high risk' category defined by the presence of additional clinical or echocardiographic risk factors. Long term anticoagulation does not appear to be justified in patients with NVAF considered to be at 'low risk' for stroke. Because the prevalence of NVAF and most other cardiovascular conditions increases with advancing age, many elderly patients will be candidates for thromboprophylaxis. The potential benefit of long term anticoagulation must be carefully weighed against the risk of serious haemorrhage in such patients. Bleeding complications with anticoagulant drugs appear to occur more frequently in older patients than in younger individuals. Advanced age (>75 years), intensity of anticoagulation [International Normalised Ratio (INR) >4.0], history of cerebral vascular disease (recent or remote), and concomitant use of drugs that interfere with haemostasis [aspirin (acetylsalicylic acid) or nonsteroidal anti-inflammatory drugs] are among the most important variables in determining an individual's risk for major bleeding with anticoagulants. Older patients often display increased sensitivity to the effects of warfarin, both in the early induction phase and during the long term maintenance phase of therapy. Conditions such as congestive heart failure, malignancy, malnutrition, diarrhoea and unsuspected vitamin K deficiency, enhance the prothrombin time response. The decision to interrupt anticoagulant therapy before elective surgery in elderly patients should evaluate the thrombotic risk of such a manoeuvre versus the risk of bleeding if anticoagulants are continued. In non-surgical patients, excessively elevated INRs without associated haemorrhage can usually be managed by simply witholding one or several doses of warfarin. If more rapid reversal is needed, small doses of phytomenadione (vitamin K1) can be administered safely without overcorrection or the development of vitamin K-induced warfarin resistance.

Relationship between test frequency and outcomes of anticoagulation: a literature review and commentary with implications for the design of randomized trials of patient self-management

BACKGROUND

Patient self-management (PSM) of anticoagulation, which is primarily based upon the premise that more frequent testing will lead to tighter anticoagulation control and thus to improved clinical outcomes, is a promising model of care. The goals of this paper are (1) to describe the strength of evidence correlating more frequent testing with improved outcomes; and (2) to discuss implications of these findings for the design of randomized controlled trials (RCTs) assessing the effectiveness and cost-effectiveness of PSM.

METHODS

We performed two literature reviews: one examining the strength of the relationship between time in target range (TTR) and the clinical outcomes of major bleeding and thromboembolism; and the second examining the strength of the relationship between frequency of testing and TTR.

RESULTS

We found that (1) the relationship between TTR and clinical outcomes is strong, thus supporting use of TTR as a primary outcome variable; and (2) more frequent testing seems to increase TTR, although the studies supporting this latter conclusion were relatively few and not definitive. Statistical analysis suggested that a study which uses clinical event rates as its primary outcome would need to be much larger than a comparable study which is based upon TTR.

CONCLUSIONS

When designing randomized trials of PSM, the design should (1) use as its control group high quality anticoagulation management rather than usual care; (2) include the maximum possible amount of self-management in the intervention group; (3) include different testing intervals in the intervention group; (4) use TTR as the primary outcome variable and event rates as a secondary outcome; and (5) base the sample size calculations upon a 5-10% absolute improvement in TTR. Additional RCTs are needed in order to determine how the promise of PSM can best be fulfilled.

Optimal intensity of warfarin therapy for secondary prevention of stroke in patients with nonvalvular atrial fibrillation : a multicenter, prospective, randomized trial. Japanese Nonvalvular Atrial Fibrillation-Embolism Secondary Prevention Cooperative Study Group

BACKGROUND AND PURPOSE

The optimal intensity of warfarin therapy for secondary prevention of stroke in nonvalvular atrial fibrillation (NVAF) remains unclear. We studied the efficacy and safety of conventional- and low-intensity warfarin therapy in a prospective, randomized, multicenter trial.

METHODS

The study population consisted of patients with NVAF (<80 years old) who had a stroke or transient ischemic attack. The patients were randomly allocated into a conventional-intensity group (international normalized ratio [INR] 2.2 to 3.5) and a low-intensity group (INR 1.5 to 2.1). They were carefully monitored, and the annual rate of recurrent ischemic stroke and major hemorrhagic complications were compared between the groups.

RESULTS

We enrolled 115 patients (mean age 66.7+/-6.5 years) into the study. Fifty-five and 60 patients were allocated into the conventional- and low-intensity groups, respectively. The trial was stopped after a follow-up of 658+/-423 days, when major hemorrhagic complications occurred in 6 patients of the conventional-intensity group and the frequency (6.6% per year) was significantly higher than that in the low-intensity group (0% per year, P=0.01, Fisher's exact test). All of the 6 patients with major bleeding were elderly (mean age 74 years), and their mean INR before the major hemorrhage was 2.8. The annual rate of ischemic stroke was low in both groups (1.1% per year in the conventional-intensity group and 1.7% per year in the low-intensity groups) and did not differ significantly.

CONCLUSIONS

For secondary prevention of stroke in persons with NVAF, especially in old patients, the low-intensity warfarin (INR 1.5 to 2. 1) treatment seems to be safer than the conventional-intensity (INR 2.2 to 3.5) treatment.

Lipoprotein(a), left atrial appendage function and thromboembolic risk in patients with chronic nonvalvular atrial fibrillation

Lipoprotein(a) (Lp(a)) has a prothrombotic effect by modulating the fibrinolytic system. The purpose of the present study was to determine whether serum Lp(a) levels are associated with an increased risk of thromboembolism in chronic nonvalvular atrial fibrillation (NVAF). Clinical, laboratory and transesophageal echocardiographic data were collected in 172 consecutive, non-anticoagulated patients with chronic NVAF. Thirty-four patients (thromboembolic group) had a recent (<1 month) embolic event and/or a left atrial thrombus on transesophageal echocardiography. The thromboembolic group had a higher frequency of spontaneous echo contrast (94 vs. 58%, p<0.0001), increased concentrations of Lp(a) (median: 31.5 vs. 15.5 mg/dl, p<0.0001) and fibrinogen (median: 352 vs. 314 mg/dl, p = 0.0015), larger left atrial dimensions (median: 5.1 vs. 4.8cm, p = 0.0078), and reduced left atrial appendage (LAA) flow velocities (median: 9.5 vs. 21.2 cm/s, p<0.0001) than the nonthromboembolic group. Multivariate analysis identified 3 independent predictors of thromboembolism: Lp(a) level > or =30 mg/dl (odds ratio (OR) 9.5, 95% confidence interval (CI) 4.4-20.4, p<0.0001), LAA flow velocity of <20 cm/s (OR 8.7, 95% CI 3.3-23.0, p = 0.0003) and a fibrinogen concentration of <377mg/dl (OR 3.2, 95% CI 1.5-6.9, p = 0.0201). The Lp(a) elevations and reduced LAA flow velocities are independently associated with thromboembolism in chronic NVAF.

Use of ambulatory electrocardiography for the detection of paroxysmal atrial fibrillation in patients with stroke. Canadian Task Force on Preventive Health Care

BACKGROUND

Patients with stroke commonly undergo investigations to determine the underlying cause of stroke. These investigations often include ambulatory electrocardiography to detect paroxysmal atrial fibrillation. There is conflicting evidence in the literature regarding whether routine ambulatory electrocardiography should be performed in all or selected stroke patients. This paper reviews the available evidence on (1) the yield of ambulatory electrocardiography in detecting paroxysmal atrial fibrillation in patients with stroke or transient ischemic attack and (2) the effectiveness of anticoagulation in preventing recurrent stroke in patients with paroxysmal atrial fibrillation.

METHODS

A MEDLINE search for primary articles was performed, and the references were reviewed manually. In addition, citations were obtained from experts. The evidence was systematically reviewed using the evidence-based methodology of the Canadian Task Force on Preventive Health Care.

RESULTS

Ambulatory electrocardiography can detect atrial fibrillation not found on initial electrocardiogram in between 1% and 5% of people with stroke. Ambulatory electrocardiography is generally safe. The risk of recurrent stroke in the setting of paroxysmal atrial fibrillation is uncertain, but appears to be similar to that seen with chronic atrial fibrillation (about 12% per year). Therapy with warfarin may reduce this risk by about two-thirds as compared to placebo. The annual risk of major bleeding with warfarin therapy is between 1% and 3% but rates for individual patients depend on various specific risk factors.

INTERPRETATION

There is insufficient evidence to recommend for or against the use of ambulatory electrocardiography for the detection of paroxysmal atrial fibrillation in either selected or unselected patients with stroke (C Recommendation). There is fair evidence to recommend therapy with warfarin for patients with stroke and paroxysmal atrial fibrillation (B Recommendation).

Advances in Therapy and the Management of Antithrombotic Drugs for Venous Thromboembolism

This review focuses on antithrombotic therapy for venous thromboembolism and covers a diverse range of topics including a discussion of emerging anticoagulant drugs, a renewed focus on thrombolytic agents for selected patients, and an analysis of the factors leading to adverse events in patients on warfarin, and how to optimize therapy. In Section I Dr. Weitz discusses new anticoagulant drugs focusing on those that are in the advanced stages of development. These will include drugs that (a) target factor VIIa/tissue factor, including tissue factor pathway inhibitor and NAPc2; (b) block factor Xa, including the synthetic pentasaccharide and DX9065a; (c) inhibit factors Va and VIIIa, i.e., activated protein C; and (d) block thrombin, including hirudin, argatroban, bivalirudin and H376/95. Oral formulations of heparin will also be reviewed.

In Section II, Dr. Comerota will discuss the use of thrombolysis for selected patients with venous thromboembolism. Fibrinolytic therapy, which has suffered from a high risk/benefit ratio for routine deep venous thrombosis, may have an important role to play in patients with iliofemoral venous thrombosis. Dr. Comerota presents his own results with catheter-directed thrombolytic therapy and the results from a large national registry showing long-term outcomes and the impact on quality of life.

In Section III, Dr. Ansell presents a critical analysis of the factors responsible for adverse events with oral anticoagulants and the optimum means of improving outcomes. The poor status of present day anticoagulant management is reviewed and the importance of achieving a high rate of “time in therapeutic range,” is emphasized. Models of care to optimize outcomes are described, with an emphasis on models that utilize patient self-testing and patient self-management of oral anticoagulation which are considered to be the ultimate in anticoagulation care. The treatment of venous and arterial thromboembolism is undergoing rapid change with respect to the development of new antithrombotic agents, an expanding list of new indications, and new methods of drug delivery and management. In spite of these changes, many of the traditional therapeutics are still with us and continue to play a vital role in the treatment of thromboembolic disease. The following discussion touches on a wide range of therapeutic interventions, from old to new, exploring the status of anticoagulant drug development, describing a new intervention for iliofemoral venous thrombosis, and analyzing the critical factors for safe and effective therapy with oral anticoagulants.

The cost-effectiveness of different management strategies for patients on chronic warfarin therapy

OBJECTIVE

To examine the cost-effectiveness of moving from usual care to more organized management strategies for patients on chronic warfarin therapy.

DESIGN

Using information available in the scientific literature, supplemented with data from a large health system and, when necessary, expert opinion, we constructed a 5-year Markov model to evaluate the health and economic outcomes associated with each of three different anticoagulation management approaches: usual care, anticoagulation clinic testing with a capillary monitor, and patient self-testing with a capillary monitor.

PATIENTS

Three hypothetical cohorts of patients beginning long-term warfarin therapy were used to generate model results.

MAIN RESULTS

Model results indicated that moving from usual care to anticoagulation clinic testing would result in a total of 1.7 thromboembolic events and 2.0 hemorrhagic events avoided per 100 patients over 5 years. Another 4.0 thromboembolic events and 0.8 hemorrhagic events would be avoided by moving to patient self-testing. When direct medical care costs and those incurred by patients and their caregivers in receiving care were considered, patient self-testing was the most cost-effective alternative, resulting in an overall cost saving.

CONCLUSIONS

Results illustrate the potential health and economic benefits of organized care management approaches and capillary monitors in the management of patients receiving warfarin therapy.

Advances in Therapy and the Management of Antithrombotic Drugs for Venous Thromboembolism

This review focuses on antithrombotic therapy for venous thromboembolism and covers a diverse range of topics including a discussion of emerging anticoagulant drugs, a renewed focus on thrombolytic agents for selected patients, and an analysis of the factors leading to adverse events in patients on warfarin, and how to optimize therapy. In Section I Dr. Weitz discusses new anticoagulant drugs focusing on those that are in the advanced stages of development. These will include drugs that (a) target factor VIIa/tissue factor, including tissue factor pathway inhibitor and NAPc2; (b) block factor Xa, including the synthetic pentasaccharide and DX9065a; (c) inhibit factors Va and VIIIa, i.e., activated protein C; and (d) block thrombin, including hirudin, argatroban, bivalirudin and H376/95. Oral formulations of heparin will also be reviewed.

In Section II, Dr. Comerota will discuss the use of thrombolysis for selected patients with venous thromboembolism. Fibrinolytic therapy, which has suffered from a high risk/benefit ratio for routine deep venous thrombosis, may have an important role to play in patients with iliofemoral venous thrombosis. Dr. Comerota presents his own results with catheter-directed thrombolytic therapy and the results from a large national registry showing long-term outcomes and the impact on quality of life.

In Section III, Dr. Ansell presents a critical analysis of the factors responsible for adverse events with oral anticoagulants and the optimum means of improving outcomes. The poor status of present day anticoagulant management is reviewed and the importance of achieving a high rate of “time in therapeutic range,” is emphasized. Models of care to optimize outcomes are described, with an emphasis on models that utilize patient self-testing and patient self-management of oral anticoagulation which are considered to be the ultimate in anticoagulation care. The treatment of venous and arterial thromboembolism is undergoing rapid change with respect to the development of new antithrombotic agents, an expanding list of new indications, and new methods of drug delivery and management. In spite of these changes, many of the traditional therapeutics are still with us and continue to play a vital role in the treatment of thromboembolic disease. The following discussion touches on a wide range of therapeutic interventions, from old to new, exploring the status of anticoagulant drug development, describing a new intervention for iliofemoral venous thrombosis, and analyzing the critical factors for safe and effective therapy with oral anticoagulants.

Prevention of thromboembolism in atrial fibrillation. A meta-analysis of trials of anticoagulants and antiplatelet drugs

OBJECTIVE

Appropriate use of drugs to prevent thromboembolism in patients with atrial fibrillation (AF) involves comparing the patient's risk of stroke and risk of hemorrhage. This review summarizes the evidence regarding the efficacy of these medications.

METHODS

We conducted a meta-analysis of randomized controlled trials of drugs used to prevent thromboembolism in adults with nonpostoperative AF. Articles were identified through the Cochrane Collaboration's CENTRAL database and MEDLINE until May 1998.

MAIN RESULTS

Eleven articles met criteria for inclusion in this review. Warfarin was more efficacious than placebo for primary stroke prevention (aggregate odds ratio [OR] of stroke = 0.30, 95% confidence interval [CI] 0.19, 0.48), with moderate evidence of more major bleeding (OR 1.90; 95% CI 0.89, 4.04). Aspirin was inconclusively more efficacious than placebo for stroke prevention (OR 0.56, 95% CI 0.19, 1.65), with inconclusive evidence regarding more major bleeds (OR 0.81, 95% CI 0.37, 1.77). For primary prevention, assuming a baseline risk of 45 strokes per 1,000 patient-years, warfarin could prevent 30 strokes at the expense of only 6 additional major bleeds. Aspirin could prevent 17 strokes, without increasing major hemorrhage. In direct comparison, there was evidence suggesting fewer strokes among patients on warfarin than among patients on aspirin (aggregate OR 0.64, 95% CI 0.43, 0.96), with only suggestive evidence for more major hemorrhage (OR 1.60, 95% CI 0.77,3.35). However, in younger patients, with a mean age of 65 years, the absolute reduction in stroke rate with warfarin compared with aspirin was low (5.5 per 1,000 person-years) compared with an older group (15 per 1,000 person-years).

CONCLUSION

In general, the evidence strongly supports warfarin for patients with AF at average or greater risk of stroke. Aspirin may prove to be useful in subgroups with a low risk of stroke, although this is not definitively supported by the evidence.

Improving management of atrial fibrillation and anticoagulation in a community hospital

BACKGROUND

Clinical trials have established the safety and efficacy of warfarin anticoagulation for stroke prevention in patients with atrial fibrillation. Other studies have documented patterns of underutilization and suboptimal warfarin therapy; physician underuse of warfarin may reflect the demands associated with monitoring the drug's effects. BASELINE STUDY: At Carney Hospital, a 230-bed acute care community teaching hospital in Boston, a retrospective chart review indicated that between July 1, 1995, and June 30, 1996, of 465 patients admitted with atrial fibrillation, 209 (45%) patients were discharged with warfarin therapy: 198 were receiving warfarin at admission, and 11 began therapy during hospitalization. Analysis of the admission international normalized ratios (INRs) indicated that a minority of patients on warfarin were safely anticoagulated at the time of admission. DESIGNING THE INTERVENTION: An anticoagulation clinic was established in fall 1997 to increase utilization of warfarin, standardize anticoagulation practices, and minimize physician time and effort needed to ensure safe anticoagulation. In early 1998 monitoring of hospitalized patients with chronic atrial fibrillation began.

RESULTS

The proportion of patients receiving warfarin therapy at admission increased from 46% in February-May 1998 to 63% in April-June 1999. Between October 1997 and July 1998, 49.1% of the 2,738 patient visits to the anticoagulation clinic showed an INR in the desired range. For the 2,238 visits during January through August 1999, 53.7% of the INRs were in the desired range.

DISCUSSION

Establishment of a clinic to oversee warfarin therapy and dissemination of indications for anticoagulation in patients with atrial fibrillation were followed by increases in the frequency of warfarin use in hospital patients and the incidence of safe therapy in ambulatory patients.

Surface plasmon resonance (SPR) analysis of coagulation in whole blood with application in prothrombin time assay

It is previously shown that surface plasmon resonance (SPR) can be used to study blood plasma coagulation. This work explores the use of this technique for the analysis of tissue factor induced coagulation, i.e. prothrombin time (PT) analysis, of whole blood and plasma. The reference method was nephelometry. The prothrombin time analysis by SPR was performed by mixing two volumes of blood/plasma, one volume of thromboplastin, and one volume of CaCl2 solution directly on a sensor surface. The measurements show good agreement between nephelometry and SPR plasma analysis and also between SPR plasma and whole blood analysis. The effect of anticoagulant treatment on the clotting times was significant both quantitatively and qualitatively. The impact on the SPR signal of different physiological events in the coagulation process is discussed, and tentative interpretations of the sensorgram features are given. The major advantage of the SPR method compared to nephelometry is the possibility to perform analysis on whole blood instead of plasma. In conclusion, SPR is a promising method for whole blood coagulation analysis.

Atrial fibrillation and thromboembolism: a decade of progress in stroke prevention

Atrial fibrillation is associated with a sixfold increased risk for stroke. More than a dozen published randomized trials of anticoagulants or antiplatelet agents for stroke prevention provide solid evidence on which to base antithrombotic prophylaxis. Adjusted-dose warfarin reduces risk for stroke by about 60% compared with placebo, aspirin reduces this risk (primarily for nondisabling stroke) by about 20% compared with placebo, and warfarin reduces it by about 40% compared with aspirin. Warfarin provides maximal protection against stroke at international normalized ratios of 2.0 to 3.0. Risk stratification of patients with atrial fibrillation identifies those who potentially benefit most or least from anticoagulation; this is important because a substantial percentage of patients with atrial fibrillation have relatively low rates of stroke if they are given aspirin. Many elderly patients with recurrent intermittent atrial fibrillation experience high rates of stroke and benefit from anticoagulation. The value of precordial or transesophageal echocardiography in addition to clinical risk stratifiers for stratifying stroke risk is controversial. Altered hemostasis favoring thrombosis may contribute to formation of atrial appendage thrombus, but these conditions remain ill defined. The past decade has brought unprecedented progress toward understanding thromboembolism in patients with atrial fibrillation and has changed the clinical perspective of a prevalent cardiac arrhythmia into an important opportunity for stroke prevention. Making the most of this promise calls for appreciation of the epidemiology of atrial fibrillation and the concept of risk specificity in the face of diverse therapeutic options.

Outcome of valve repair and the Cox maze procedure for mitral regurgitation and associated atrial fibrillation

OBJECTIVE

The objective was to determine whether the Cox maze procedure provides adjunctive benefit in patients with atrial fibrillation undergoing mitral valve repair.

METHODS

We compared the outcome of 39 patients who had the Cox maze procedure plus mitral valve repair between January 1993 and December 1996 (maze group) with that of 58 patients with preoperative atrial fibrillation who had mitral valve repair during the same interval by the same surgeons (control group). Patients in the 2 cohorts were similar for age, gender, preoperative New York Heart Association class III or IV, and duration of preoperative atrial fibrillation. The control group had a higher incidence of previous heart surgery and coronary artery disease.

RESULTS

No operative deaths occurred, and 1 patient in each group required pacemaker implantation after the operation. Duration of cardiopulmonary bypass (122 +/- 40 minutes vs 58 +/- 27 minutes, P <.0001) and hospitalization (12.6 +/- 6.4 vs 9.3 +/- 3.4 days, P <.0025) were prolonged in patients having the Cox maze procedure. Overall, 2-year survival was similar (92% +/- 5% for maze patients and 96% +/- 3% for controls). Freedom from atrial fibrillation in the maze group was 74% +/- 8% 2 years after the operation compared with 27% +/- 7% for the control group (P <.0001). Freedom from stroke or anticoagulant-associated bleeding in the maze group was 100% 2 years after the operation compared with 90% +/- 8% in the control group (P =.04). At most recent follow-up, 82% of maze patients were in normal sinus rhythm (53% in control group).

CONCLUSION

The addition of the Cox maze procedure to mitral valve repair is safe and effective for selected patients, and elimination of atrial fibrillation decreased late complications.

Non-rheumatic atrial fibrillation and stroke

The risk of systemic embolism and stroke in patients with non-rheumatic atrial fibrillation (NRAF) should not be underestimated. The annual embolic rate is approximately 5% and in those with left atrial enlargement and/or left ventricular (LV) dysfunction, or who have already had systemic embolism, this rate may be as high as 20%. Decisions on patient management and the prophylaxis of stroke must always be individualised. The risk of bleeding related to warfarin is almost certainly greater than that encountered in the previous randomised trials. Also, clinical and echocardiographic features can further define absolute risk in an individual patient with NRAF. Clinical markers of increased risk of embolism in patients with NRAF include older age, previous cerebral embolism, recent congestive heart failure, hypertension and diabetes mellitus. Transthoracic echocardiography improves risk stratification and should be performed in the vast majority of patients. Embolic risk is greatest in those with increasing left atrial dilation, atrial dysfunction and LV dysfunction. Transoesophageal echocardiography sharpens the risk profile in selected patients. Overall randomised trials show greater benefit with warfarin than aspirin. In general, increasing age is associated with a greater incidence of structural heart disease and probably implies greater potential benefit with warfarin. Increasing age per se may not increase the risk of warfarin-related bleeding. When the decision is made to warfarinise patients, at the present time data suggest that the target INR should be in the range of 2.0-3.0.

Oral anticoagulation in nonvalvular atrial fibrillation

Chronic nonvalvular atrial fibrillation is associated with an overall risk of thromboembolic complications of 4.5% per year. Advancing age, prior stroke or transient cerebral ischaemia, diabetes, hypertension, and impaired function of the left ventricle are known risk factors. Placebo-controlled trials have demonstrated that oral anticoagulant therapy with warfarin is effective for primary and secondary prevention of ischaemic stroke, reducing the risk by 68%. The effect of aspirin is still controversial, reducing the risk by 18-44%. Recent clinical trials have investigated the effect of warfarin given at a very low intensity alone or combined with aspirin. The results from the SPAF III study demonstrated that a combination of mini-intensity warfarin plus aspirin was insufficient for stroke prevention in atrial fibrillation. More trials have now confirmed that oral anticoagulation at INR-values below 2.0 is not effective for prevention of thromboembolic events in these patients. It is currently recommended that patients at a high risk of stroke are treated with warfarin at an intensity of INR 2.0-3.0. Patients younger than 65 years without other risk factors can be given aspirin 325 mg day-1.

Oral anticoagulant treatment in patients with mechanical heart valves: how to reduce the risk of thromboembolic and bleeding complications

Patients with mechanical heart valves have a high risk of thrombus formation on the valve and subsequent systemic embolism. These patients therefore need to receive life-long oral anticoagulation (OAC). Despite this treatment, the overall incidence rate of major thromboembolic complications is still about 1-2 per 100 patient-years. Additionally, these patients have an increased risk of bleeding complications, ranging between 1 and 7 per 100 patient-years. To reduce both types of often very serious complications, the optimal intensity of anticoagulation needs to be established. We found a fairly wide optimal range between 2.5 and 4.9 INR (international normalized ratio) at which the incidence of both untoward events was minimal. As a target intensity, we recommend opting for the middle of this range (INR 3.0-4.0), thereby providing a safe margin at both ends. In order to further reduce thromboembolic and bleeding complications, two approaches can be considered: first of all, the management of OAC treatment needs to be optimized in order to achieve a stable therapeutic effect in as many patients as possible. Secondly, patient characteristics need to be identified that increase the thromboembolic or bleeding risk. Subsequently, the optimal intensity may need to be adjusted accordingly, at an individual level. Possible risk factors for an increased thromboembolic risk are position and type of the prosthesis. Age may increase both the risk of thromboembolism and the risk of haemorrhage.

Anticoagulant treatment of patients with atrial fibrillation in primary health care

OBJECTIVE

To determine the prevalence of anticoagulant (AC) treatment of patients with atrial fibrillation in primary health care. To identify complications in the same patients during 1 year.

DESIGN

Cross-sectional study and 1-year follow-up.

SETTING

Seven health centres with a total population of 164093.

SUBJECTS

Five hundred and twenty-two anticoagulated patients with atrial fibrillation.

RESULTS

The age-adjusted prevalence of AC treated patients with atrial fibrillation was 0.30%. Of the 522 patients, 240 were men, mean age 69.6 years; and 282 women, mean age 75.1 years. At the beginning of the study 85% and after 1 year 81% of the latest prothrombin time values were within recommended range. After 1 year 414 out of the 522 patients continued AC treatment. During the 1-year follow-up 62 patients had minor or major complications. Eleven patients (2.1%) had to discontinue AC treatment because of complications. Prothrombin tests were mainly taken at 3-4 week intervals.

CONCLUSION

High quality AC treatment is possible in the hands of general practitioners.

Diagnosis and treatment of ischemic stroke

Most patients who have a stroke are evaluated initially by a primary care physician. For patients to benefit from new stroke therapies that must be initiated within a few hours of stroke onset, primary care physicians must be prepared to diagnose stroke and initiate acute treatment. This article provides information on the rapid and accurate diagnosis and management of patients with acute ischemic stroke. This information is particularly relevant due to the relatively high risk:benefit ratio associated with some acute stroke therapies, such as tissue plasminogen activator. Information is also provided about medical and surgical therapies to prevent subsequent strokes.

Evidence-based guidelines for early stroke management

Stroke disease is the commonest neurological emergency encountered by the junior medical team. We have reviewed the literature to produce a series of substantiated guidelines to assist the admitting doctor in managing early stroke care optimally.

Accuracy of a portable International Normalization Ratio monitor in outpatients receiving long-term oral anticoagulant therapy: comparison with a laboratory reference standard using clinically relevant criteria for agreement

The accuracy of a new, portable INR monitor (CoaguChek, Boehringer-Mannheim, Indianapolis, IN) was evaluated by comparing INR results from the portable monitor with results obtained by a laboratory-based method. Dual INR measurements (portable monitor, laboratory) were performed in 163 consecutive outpatients receiving warfarin. Agreement in dual INR measurements was defined based on clinically-relevant expanded and narrow criteria and statistical criteria. Agreement in dual INR measurements also was evaluated as a function of increasing INR. The proportion of dual INR measurements that satisfied the clinically-relevant expanded, and narrow agreement criteria was 90%, and 86%, respectively. Seventy-nine percent of all dual measurements were within 0.5 INR units. The accuracy of the portable monitor was greatest for INR values less than 3.0; above this INR level, the portable monitor underestimated laboratory INR values. The proportion of dual INR measurements within 0.5 INR units for laboratory INR ranges of <2.0, 2.0-3.0, 3.1-4.0, and >4.0 was 98%, 87%, 57%, and 21%, respectively. We conclude that the portable INR monitor achieved a clinically acceptable level of accuracy when compared to the traditional laboratory method and provides a suitable alternative method of monitoring the INR in patients receiving warfarin.

Audit of the frequency and clinical response to excessive oral anticoagulation in an out-patient population

A retrospective review of over-anticoagulated patients with critical international normalized ratios (INRs) was undertaken in a large outpatient laboratory. In the six-month study period, 85 prothrombin times (PTs) were identified with an INR of > or = 6.0, an overall incidence of elevated PTs of 0.2% or two per 1,000 INR tests. Complete follow-up data was available on 65 patients. When compared to an age- and gender-matched control group without INR > or = 6.0, high-INR patients were significantly more likely to manifest the presence of alcoholism or liver disease, to have been anticoagulated for less than six months, to have experienced more frequent warfarin dosage changes, and to have had the addition of a medication known to interact with warfarin. In the high-INR group, a likely cause for the specific critical INR was identified in 44 patients (68%). Drug interactions followed by compliance problems were the most common factors identified. The 13 patients (20%) who received vitamin K therapy experienced no difference in the clinical outcome compared with those managed conservatively. Conservative management of critically high INR values appeared to be as efficacious as intervention with vitamin K therapy.

Prevention of stroke in patients with nonvalvular atrial fibrillation

OBJECTIVE

To review the risk and pathogenesis of stroke associated with nonvalvular atrial fibrillation (AF) and the efficacies and risks of stroke prevention strategies.

BACKGROUND

About 16% of ischemic strokes are associated with AF; AF is an independent risk factor for stroke.

METHODS

Review of the literature, focusing on 13 randomized trials of antithrombotic therapy.

RESULTS

The overall risk of stroke in AF patients averages about 5%/y, but with wide variation depending on the presence of coexistent thromboembolic risk factors. AF patients with low (about 1% per year), moderate (about 3% per year), and high (about 6% per year) stroke risks have been identified, but the generalizability of risk stratification schemes to clinical practice has not been fully assessed. AF patients with prior stroke or transient ischemic attack, even if remote, are at highest risk (about 12% per year). Adjusted-dose warfarin (target International Normalized Ratio [INR] 2-3) is highly efficacious for preventing stroke in AF patients (about 70% risk reduction) and is safe for selected patients, if carefully monitored. Aspirin has a modest effect on reducing stroke (about 20% risk reduction). The numbers of AF patients that would need to be treated with warfarin instead of aspirin for 1 year to prevent one ischemic stroke are about 200, 70, and 20 for those with low, moderate and high risk, respectively.

CONCLUSIONS

Many patients with nonvalvular AF have substantial rates of ischemic stroke. Stratification of stroke risk identifies AF patients who benefit most and least from lifelong anticoagulation. Warfarin is recommended for high-risk AF patients who can safely receive it. Aspirin may be indicated for those with a low stroke risk and for those who cannot receive warfarin. For AF patients considered to have a moderate risk of stroke, individual bleeding risk during anticoagulation and patient preference should particularly influence the choice of antithrombotic prophylaxis.

A new regimen for starting warfarin therapy in out-patients

AIMS

Oral anticoagulation is increasingly used in elderly patients with atrial fibrillation to prevent embolic phenomena. The use of anticoagulants in this population is prophylactic rather than therapeutic and so there is no urgency to establish anticoagulation within the desired therapeutic range. The aim of the study was to develop an out-patient regimen for initiation of oral anticoagulation with warfarin which requires only weekly monitoring of the International Normalized Ratio (INR).

METHODS

The study was undertaken in two phases. In the first phase, factors which predict the final maintenance dosage of warfarin were defined and used to build a decision tree and dosage algorithm. In the second study the algorithm was tested. Patients were given 2 mg warfarin daily for 2 weeks and the INR at this time was used to predict the maintenance dose. Patients then attended for weekly measurements of the INR until steady state had been reached. Dosage adjustments were not made unless the INR was >4.0 or <1.5 for 2 consecutive weeks. The accuracy of the prediction was measured by calculating the mean INR of weeks 6-8 and the number of patients in the target range 2.0-3.0 was determined.

RESULTS

One hundred and seven consecutive out-patients (mean age 70 years range 64-86) completed the first study. The age, sex, height, weight, alcohol intake, number of cigarettes smoked, concomitant medication, clinical evidence of right heart failure, liver failure, abnormalities in liver enzyme estimations, baseline INR and INR after 2 weeks of 2 mg warfarin daily were used in a polytomous logistic regression analysis with stepwise inclusion of factors to determine which factors influenced the eventual maintenance dosage of warfarin. The INR after 2 weeks of 2 mg warfarin therapy predicted 70% of the variability of the maintenance dose. Of other factors only the sex of the patient had a large enough effect to be included in the prediction algorithm. One hundred and six patients (mean age 71 years range 50-85 years) completed the second study. Only one patient needed a dose adjustment in the first 2 weeks of warfarin 2 mg daily (INR 4.4). Overall, 60% patients were in the narrow target range (INR 2.0-3.0) at steady state. In five patients the INR was >4.0 at any visit after the second week and needed dosage adjustment. In four patients the INR was <1.5 at steady state.

CONCLUSIONS

We have developed a method of predicting the maintenance dose of warfarin in an elderly population based on the INR after 2 weeks of warfarin 2 mg daily, and the sex of the patient. This is a safe and convenient way of initiating warfarin therapy as an out-patient which requires only weekly INR checks.

Microembolic load in asymptomatic patients with cardiac aneurysm, severe ventricular dysfunction, and atrial fibrillation. Clinical and hemorheological correlates

Transcranial Doppler sonography has become a widely used method for detecting cerebral circulating microemboli (ME) arising from the carotid arteries or the heart. Yet, studies on subgroups of patients with distinct cardiac sources of embolism are still limited. The same holds true for investigation on the relationship between microembolization and hemorheological parameters. A total of 142 patients suffering from left ventricular aneurysm (LVA, n = 52), severe left ventricular dysfunction (LVD, n = 43), or chronic atrial fibrillation (AF, n = 47) were enrolled in this study. All patients had been neurologically asymptomatic for at least 1 month. Further relevant embolic disorders of the carotid arteries and the heart had been excluded. Unilateral monitoring for ME over the middle cerebral artery was performed for 30 min. Blood was drawn after each monitoring for determination of plasmatic coagulation parameters, as well as plasma viscosity, and platelet reactivity. The overall prevalence of ME was 31%, with a slightly higher prevalence in patients with LVA (37%) compared to patients suffering from AF (30%) or LVD (26%). With single-factor analysis, a trend towards higher ME prevalences was found with (a) a history of remote embolic events, (b) ineffective anticoagulation, (c) increased platelet aggregation, or (d) increased plasma viscosity (all p > 0.1). The combination of ineffective anticoagulation in conjunction with increased platelet aggregation, however, was significantly associated with higher ME rates even after adjustment for other factors by logistic regression analysis. Our results demonstrate a low ongoing microembolic activity in asymptomatic patients suffering from LVA, LVD and AF. An activated plasmatic coagulation system together with increased platelet aggregation contributes to ME generation.

Modern management of prosthetic valve anticoagulation

Prosthetic heart valves have been effectively used for many years. Nonetheless, they are associated with risks of thrombosis and thromboembolic events, as well as anticoagulation-induced bleeding. Substantial changes in anticoagulation measurement and dosing have occurred during the past several years. In this review, the rationale for anticoagulation in patients with prosthetic heart valves, the changes in monitoring and dosing, and the comparison of relevant anticoagulation trials are discussed. On the basis of the existing data, new recommendations regarding lower anticoagulation levels are offered, utilizing a single value goal rather than the traditional therapeutic range. Perioperative management of anticoagulation is discussed in light of the available literature, and major drug interactions are reviewed.

Cost-effectiveness of preference-based antithrombotic therapy for patients with nonvalvular atrial fibrillation

BACKGROUND AND PURPOSE

Recent atrial fibrillation guidelines recommend the incorporation of patient preferences into the selection of antithrombotic therapy. However, no trial has examined how incorporating such preferences would affect quality-adjusted survival or medical expenditure. We compared 10-year projections of quality-adjusted survival and medical expenditure associated with two atrial fibrillation treatment strategies: warfarin-for-all therapy versus preference-based therapy. The preference-based strategy prescribed whichever antithrombotic therapy, warfarin or aspirin, had the greater projected quality-adjusted survival.

METHODS

We used decision analysis stratified by the number of stroke risk factors (history of stroke, transient ischemic attack, hypertension, diabetes, or heart disease). The base case focused on compliant 65-year-old patients who had nonvalvular atrial fibrillation and no contraindications to antithrombotic therapy.

RESULTS

In patients whose only risk factor for stroke was atrial fibrillation, preference-based therapy improved projected quality-adjusted survival by 0.05 quality-adjusted life year (QALY) and saved $670. For patients who had atrial fibrillation and one additional risk factor for stroke, preference-based therapy improved quality-adjusted survival by 0.02 QALY and saved $90. In patients who had atrial fibrillation and multiple additional risk factors for stroke, preference-based therapy increased medical expenditures and did not improve quality-adjusted survival substantially. The benefits of preference-flexible therapy arose from the minority of patients who would have had a longer quality-adjusted survival if they had been prescribed aspirin rather than warfarin.

CONCLUSIONS

As do risks of stroke and of hemorrhage, patients' preferences help to determine which antithrombotic therapy is optimal. Preference-based treatment should improve quality-adjusted survival and reduce medical expenditure in patients who have nonvalvular atrial fibrillation and not more than one additional risk factor for stroke.

A warfarin induction regimen for out-patient anticoagulation in patients with atrial fibrillation

Currently available protocols for induction of warfarin anticoagulation employ initial doses of 10 mg and are best suited to in-patient use. However, with the increasing number of elderly patients with atrial fibrillation requiring anticoagulation, there is a need for a less intense regimen which could be used for out-patients. We have established such a regimen and report on its prospective evaluation in 3 7 patients referred for out-patient initiation of warfarin, and a non-randomized comparison with 37 in-patients, with similar diagnoses, commenced on a traditional warfarin protocol. After exclusion of five patients on amiodarone, all of whom experienced supratherapeutic International Normalized Ratio (INR) results, the new out-patient regimen, employing an initial 5 mg dose, resulted in a lower maximum INR during the first 21 d therapy (median 2.9 v 4.0; P = 0.0001) and fewer INRs >4.5 (2/36 v 9/33) compared to the traditional 10 mg regimen. Time to reach stable anticoagulation was similar with each regimen; however, the 5 mg regimen gave a more accurate prediction of maintenance dose (correlation coefficient for predicted versus actual maintenance dose, r = 0.985). In comparison to a traditional 10 mg protocol, the proposed 5 mg warfarin induction regimen proved both safer and more reliable for initiation of prophylactic anticoagulation in patients with atrial fibrillation.

Update on Atrial Fibrillation: Restoration of Sinus Rhythm or Ventricular Rate Control?

In patients with persistent atrial fibrillation, two therapeutic alternatives exist, namely restoration and maintenance of sinus rhythm versus ventricular rate control combined with anticoagulation. Currently, the selection of the best therapeutic strategy in an individual patient relies for the most part on clinical judgement and personal experience. At present, there are no prospective scientific data to support the superiority of one treatment over the other with respect to overall survival or quality of life. This review summarizes the present knowledge on this important clinical problem with particular emphasis on issues such as efficacy of antiarrhythmic drugs to prevent recurrent atrial fibrillation, proarrhythmic hazards of these compounds, or efficacy and safety of anticoagulation in nonrheumatic atrial fibrillation. These data serve as the basis of ongoing clinical trials prospectively comparing the merits and demerits of the two therapeutic strategies in the most common arrhythmia encountered in clinical practice.

Thromboembolic complication in atrial fibrillation in a long-term follow-up--the relationship with underlying disease, type of atrial fibrillation, and antithrombotic therapy

The incidence of thromboembolic complications among 288 patients with atrial fibrillation (AF) who were followed up during an average period of 7.2 years was examined retrospectively. The annual incidence of thromboembolic complications was 1.6% in total, 1.7% in valvular heart disease (n=128), and 2.1% in non-valvular heart disease (n=117). No thromboembolism occurred in lone AF (n=43), defined as the complete absence of any underlying disease. The type of AF before embolic attack was chronic in 26 cases and paroxysmal in 6 cases. The cardiac rhythm at the time of the embolic attack was AF, except in 2 cases in which ECG was not recorded. In all patients with thromboembolic complications who were receiving antithrombotic therapy during the follow-up, the anticoagulant effect just before the embolic attack was found to be insufficient. Major bleeding was not observed in the patients receiving antithrombotic therapy. Thromboembolism in AF in long-term follow-up tends to occur more frequently in patients with underlying heart disease and in those with chronic AF compared rather than paroxysmal AF; it rarely occurs in lone AF. We should not hesitate to administer sufficient anticoagulant therapy in AF patients who are at high risk of developing thromboembolic complications.

Randomized trial of an oral platelet glycoprotein IIb/IIIa antagonist, sibrafiban, in patients after an acute coronary syndrome: results of the TIMI 12 trial. Thrombolysis in Myocardial Infarction

BACKGROUND

Inhibitors of the platelet glycoprotein IIb/IIIa receptor given intravenously have been shown to be effective in reducing ischemic complications after coronary angioplasty and in unstable angina, making this a promising new class of agents for the treatment and prevention of ischemic events in patients with acute coronary syndromes. Sibrafiban (Ro 48-3657) is an oral, peptidomimetic, selective antagonist of the glycoprotein IIb/IIIa receptor.

METHODS AND RESULTS

The Thrombolysis in Myocardial Infarction (TIMI) 12 trial was a phase II, double-blind, dose-ranging trial designed to evaluate the pharmacokinetics (PK), pharmacodynamics (PD), safety, and tolerability of sibrafiban in 329 patients after acute coronary syndromes. In the PK/PD cohort of TIMI 12, 106 patients were randomized to receive one of seven dosing regimens of sibrafiban, ranging from 5 mg daily to 10 mg twice daily for 28 days. In the safety cohort, 223 patients were randomized to one of four dose regimens of sibrafiban (ranging from 5 mg twice daily to 15 mg once daily) or aspirin for 28 days. High levels of platelet inhibition were achieved: mean peak values ranged from 47% to 97% inhibition of 20 micromol/L ADP-induced platelet aggregation on day 28 across the seven doses. Twice-daily dosing provided more sustained platelet inhibition (mean inhibition, 36% to 86% on day 28), whereas platelet inhibition returned to baseline levels by 24 hours with once-daily dosing. Major hemorrhage occurred in 1.5% of patients treated with sibrafiban and in 1.9% of patients treated with aspirin. Protocol-defined "minor" bleeding, usually mucocutaneous, occurred in 0% to 32% of patients in the various sibrafiban groups and in none of the patients treated with aspirin. Minor bleeding was related to total daily dose (P=.002), once- versus twice-daily dosing (P<.0001), renal function (P<.0001), and presentation with unstable angina (P<.01).

CONCLUSIONS

The oral glycoprotein IIb/IIIa antagonist sibrafiban achieved effective, long-term platelet inhibition with a clear dose-response but at the expense of a relatively high incidence of minor bleeding. Oral IIb/IIIa inhibition deserves further study as a new treatment strategy in patients after acute coronary syndromes.

Differences in medical and surgical therapy for stroke prevention between leading experts in North America and Western Europe

BACKGROUND AND PURPOSE

Large multicenter trials have evaluated the benefit of different medical and surgical therapies to prevent stroke. However, the application of trial results to clinical practice remains uncertain for some areas of stroke prevention and has been discussed passionately among international experts. As part of a worldwide survey, the purpose of this analysis was to provide an informative and comparative view of the current practice of leading experts in North America (NA) and Western Europe (WE), where most of the large prevention trials have been performed.

METHODS

The survey was performed worldwide among 185 neurologists who are currently leading the discussions of stroke prevention practices. It contained questions on the use of antiplatelet agents, oral anticoagulation, and surgery for the prevention of ischemic stroke. The population of this present analysis is the two groups of experts from WE (n=73) and NA (n=48) exclusively.

RESULTS

Of each group, >90% responded to the survey. Nearly all respondents reported prescribing aspirin in patients at risk of atherothrombotic stroke, but significant differences between NA and WE are shown by the recommended doses (P<.0001): aspirin doses of >500 mg daily are given exclusively by American participants (36%), whereas doses <200 mg are recommended only in Europe (51%). Eighty-six percent of American versus 59% of European respondents reported using ticlopidine as their second choice (P<.005), and 23% of respondents from WE used warfarin compared with 5% from NA (P<.05). The reported use of anticoagulants in patients with atrial fibrillation increased in accordance with the patient's individual risk of stroke, but respondents from WE were more reluctant to use anticoagulants in patients older than 75 years. Relatively higher target international normalized ratio values were reported by European respondents. Nearly all participants recommend carotid endarterectomy in patients with symptomatic carotid stenosis. The use of carotid endarterectomy in asymptomatic patients was significantly more common among responding experts from NA (48% versus 28%; P<.05), particularly in patients with >95% stenosis (89% versus 53%; P<.0005).

CONCLUSIONS

This analysis shows significant differences in several areas of stroke prevention practices between leading experts from NA and WE. These differences may be explained partly by divergent results of trials from the two continents, but in some areas of controversy currently available trial data are not sufficient to form an international consensus to guide daily clinical practice.

Long-term oral anticoagulation reduces bone mass in patients with previous hemispheric infarction and nonrheumatic atrial fibrillation

BACKGROUND AND PURPOSE

Vitamin K is an essential factor for synthesis of plasma clotting proteins and for site-specific carboxylation of bone Gla protein and other bone matrix proteins. Low vitamin K has been associated with reduced bone mineral density. Warfarin therapy, which inhibits vitamin K-dependent blood-clotting, has been demonstrated to reduce the risk of stroke in nonrheumatic atrial fibrillation. We evaluated vitamin K and bone mineral density in nonrheumatic atrial fibrillation patients who had long-term warfarin therapy after an ischemic stroke.

METHODS

Sera were collected from 64 patients with non-rheumatic atrial fibrillation and ischemic stroke who had been treated with warfarin, 63 stroke patients without warfarin, and 39 control subjects. All stroke patients in both groups had hemiplegia. Sera were assayed for vitamins K1 and K2, bone Gla protein, and 25-hydroxyvitamin D. Bone mineral density was determined in both second metacarpals.

RESULTS

Serum vitamin K1 concentrations (ng/mL) were lower in treated patients (.234 +/- .177 ng/mL) than in untreated patients (.329 +/- .284) or controls (.553 +/- .164). Bone Gla protein was lower in treated patients' sera (1.241 +/- .799 ng/mL) than in untreated patients (4.476 +/- 3.226). Concentrations of 25-hydroxyvitamin D were lower in both patient groups. Bone mineral density was lower on both sides in treated patients than in untreated patients (P < .0001). Vitamin K1 and bone Gla protein were significantly related to bone mineral density bilaterally in treated but not in untreated patients.

CONCLUSIONS

Bone mineral density was significantly lower in stroke patients with long-term warfarin treatment than in untreated patients. Both warfarin-induced reduction in vitamin K function and lowered vitamin K1 concentrations are probable causes of this osteopenia.

A randomized trial of anticoagulants versus aspirin after cerebral ischemia of presumed arterial origin. The Stroke Prevention in Reversible Ischemia Trial (SPIRIT) Study Group

Aspirin is only modestly effective in the secondary prevention after cerebral ischemia. Studies in other vascular disorders suggest that anticoagulant drugs in patients with cerebral ischemia of presumed arterial (noncardiac) origin might be more effective. The aim of the Stroke Prevention in Reversible Ischemia Trial (SPIRIT) therefore was to compare the efficacy and safety of 30 mg aspirin daily and oral anticoagulation (international normalized ratio [INR] 3.0-4.5). Patients referred to a neurologist in one of 58 collaborating centers because of a transient ischemic attack or minor ischemic stroke (Rankin grade < or =3) were eligible. Randomization was concealed, treatment assignment was open, and assessment of outcome events was masked. The primary measure of outcome was the composite event "death from all vascular causes, nonfatal stroke, nonfatal myocardial infarction, or nonfatal major bleeding complication." The trial was stopped at the first interim analysis. A total of 1,316 patients participated; their mean follow-up was 14 months. There was an excess of the primary outcome event in the anticoagulated group (81 of 651) versus 36 of 665 in the aspirin group (hazard ratio, 2.3; 95% confidence interval [CI], 1.6-3.5). This excess could be attributed to 53 major bleeding complications (27 intracranial; 17 fatal) during anticoagulant therapy versus 6 on aspirin (3 intracranial; 1 fatal). The bleeding incidence increased by a factor of 1.43 (95% CI, 0.96-2.13) for each 0.5 unit increase of the achieved INR. Anticoagulant therapy with an INR range of 3.0 to 4.5 in patients after cerebral ischemia of presumed arterial origin is not safe. The efficacy of a lower intensity anticoagulation regimen remains to be determined.

High concentration of thrombomodulin in plasma is associated with hemorrhage: a prospective study in patients receiving long-term anticoagulant treatment

BACKGROUND

The aim of this study was to prospectively test whether the risk of bleeding complications in 212 consecutive outpatients treated with oral anticoagulants could be predicted by levels of endothelium-derived hemostatic variables.

METHODS AND RESULTS

All bleeding complications were recorded during 5 years of follow-up; serious bleeding was defined as intracranial bleeding or hemorrhage causing death or necessitating hospitalization. The relationships of bleeding complications and plasma concentrations of tissue plasminogen activator, von Willebrand factor, and thrombomodulin, plasminogen activator inhibitor activity, and other possible risk factors were studied. Twenty-two patients suffered from bleeding complications during anticoagulant treatment; in 14 patients, these were serious. We found that the numbers both of serious hemorrhages and of total hemorrhages were significantly associated with increased levels of thrombomodulin. The number of bleeding episodes increased exponentially through quartiles one to four of the thrombomodulin distribution.

CONCLUSIONS

Thrombomodulin concentrations in plasma are related to the risk of hemorrhage in patients treated with oral anticoagulants.