Stroke severity in patients with atrial fibrillation

Severity of Ischemic Stroke After Left Atrial Appendage Closure vs Nonwarfarin Oral Anticoagulants

BACKGROUND

Strokes after left atrial appendage closure (LAAC) prophylaxis are generally less severe than those after warfarin prophylaxis-thought to be secondary to more hemorrhagic strokes with warfarin. Hemorrhagic strokes are similarly infrequent with direct oral anticoagulant (DOAC) prophylaxis, so the primary subtype after either LAAC or DOAC prophylaxis is ischemic stroke (IS).

OBJECTIVES

The purpose of this study was to compare the severity of IS using the modified Rankin Scale in atrial fibrillation patients receiving prophylaxis with DOACs vs LAAC.

METHODS

A retrospective analysis was performed of consecutive patients undergoing LAAC at 8 centers who developed an IS (ISLAAC) compared with contemporaneous consecutive patients who developed IS during treatment with DOACs (ISDOAC). The primary outcome was disabling/fatal stroke (modified Rankin Scale 3-5) at discharge and 3 months later.

RESULTS

Compared with ISDOAC patients (n = 322), ISLAAC patients (n = 125) were older (age 77.2 ± 13.4 years vs 73.1 ± 11.9 years; P = 0.002), with higher HAS-BLED scores (3.0 vs 2.0; P = 0.004) and more frequent prior bleeding events (54.4% vs 23.6%; P < 0.001), but similar CHA2DS2-VASc scores (5.0 vs 5.0; P = 0.28). Strokes were less frequently disabling/fatal with ISLAAC than ISDOAC at both hospital discharge (38.3% vs 70.3%; P < 0.001) and 3 months later (33.3% vs 56.2%; P < 0.001). Differences in stroke severity persisted after propensity score matching. By multivariate regression analysis, ISLAAC was independently associated with fewer disabling/fatal strokes at discharge (OR: 0.22; 95% CI: 0.13-0.39; P < 0.001) and 3 months (OR: 0.25; 95% CI: 0.12-0.50; P < 0.001), and fewer deaths at 3 months (OR: 0.28; 95% CI: 0.12-0.64; P < 0.001).

CONCLUSIONS

Ischemic strokes in patients with atrial fibrillation are less often disabling or fatal with LAAC than DOAC prophylaxis.

Net Clinical Benefit of Oral Anticoagulation Among Older Adults With Atrial Fibrillation

BACKGROUND

While guidelines recommend anticoagulation for all atrial fibrillation (AF) patients ≥75 years, evidence for the net clinical benefit (NCB) of anticoagulant in older adults is sparse. We sought to determine the association between age and NCB of anticoagulation in older adults with AF.

METHODS AND RESULTS

We examined adults ≥75 years with incident AF in the Anticoagulation and Risk Factors in Atrial Fibrillation-Cardiovascular Research Network cohort. Using a Markov state transition model, we estimated the lifetime NCB of warfarin and apixaban relative to no treatment in quality-adjusted life years (QALYs). In the decision model, each month patients face a chance of stroke, hemorrhage, or death from a competing cause; the likelihood of each is a function of individual patients' stroke risk, hemorrhage risk, and life expectancy. We defined minimal clinically relevant lifetime benefit as 0.10 QALYs. In a sensitivity analysis, we examined the effect of competing risks of death on NCB using 2 models, one including competing risks and the second without competing risks. We included 14 946 patients, with a median age of 81 years and median CHA₂DS₂-VASc score of 4. In the main analysis, after age 87, NCB associated with warfarin decreased below 0.10 lifetime QALYs while NCB associated with apixaban did not decrease below 0.10 lifetime QALYs until after age 92. In sensitivity analyses, over a 3-year horizon, removing competing risks of death resulted in higher NCB (at 90 years, median difference using warfarin 0.010 QALYs [95% CI, 0.009-0.013], median difference using apixaban 0.025 QALYs [95% CI, 0.024-0.026]).

CONCLUSIONS

The NCB of anticoagulation decreases with advancing age. The competing risk of death diminishes the NCB of anticoagulation for older patients with AF. Physicians should consider competing mortality risks when recommending anticoagulants to older adults with AF.

Geographic Disparities in the Incidence of Stroke among Patients with Atrial Fibrillation in the United States

AIM

To determine whether regional variation in stroke incidence exists among individuals with AF.

METHODS

Using healthcare utilization claims from 2 large US databases, MarketScan (2007-2014) and Optum Clinformatics (2009-2015), and the 2010 US population as the standard, we estimated age-, sex-, race- (only in Optum) standardized stroke incidence rates by the 9 US census divisions. We also used Poisson regression to examine incidence rate ratios (IRR) of stroke and the probability of anticoagulation prescription fills across divisions.

RESULTS

Both databases combined included 970,683 patients with AF who experienced 15,543 strokes, with a mean follow-up of 23 months. In MarketScan, the age- and sex-standardized stroke incidence rate was highest in the Middle Atlantic and East South Central divisions at 3.8/1000 person-years (PY) and lowest in the West North Central at 3.2/1000 PY. The IRR of stroke and the probability of anticoagulation fills were similar across divisions. In Optum Clinformatics, the age-, sex-, and race-standardized stroke incidence rate was highest in the East North Central division at 5.0/1000 PY and lowest in the New England division at 3.3/1000 PY. IRR of stroke and the probability of anticoagulation fills differed across divisions when compared to New England.

CONCLUSIONS

These findings suggest regional differences in stroke incidence among AF patients follow a pattern that differs from the hypothesized trend found in the general population and that other factors may be responsible for this new pattern. Cross-database differences provide a cautionary tale for the identification of regional variation using health claims data.

Effect of Variation in Published Stroke Rates on the Net Clinical Benefit of Anticoagulation for Atrial Fibrillation

BACKGROUND

Stroke rates in patients with nonvalvular atrial fibrillation (AF) who are not receiving anticoagulant therapy vary widely across published studies; the resulting effect on the net clinical benefit of anticoagulation in AF is unknown.

OBJECTIVE

To determine the effect of variation in published AF stroke rates on the net clinical benefit of anticoagulation.

DESIGN

Markov model decision analysis. Warfarin was the base case, and non-vitamin K antagonist oral anticoagulants (NOACs) were modeled in a secondary analysis.

SETTING

Community-dwelling adults.

PATIENTS

33 434 adults with incident AF.

MEASUREMENTS

Quality-adjusted life-years (QALYs).

RESULTS

Of the 33 434 patients, 27 179 had a CHA2DS2-VASc (congestive heart failure, hypertension, age, diabetes, stroke, and vascular disease) score of 2 or more. The population benefit of warfarin anticoagulation for these patients was least using stroke rates from the ATRIA (AnTicoagulation and Risk Factors In Atrial Fibrillation) study and greatest using those from the Danish National Patient Registry (6290 QALYs [95% CI, ±2.3%] vs. 24 110 QALYs [CI, ±1.9%]; P < 0.001). The optimal CHA2DS2-VASc score threshold for anticoagulation was 3 or more using stroke rates from ATRIA, 2 or more using those from the Swedish AF cohort study, 1 or more using those from the SPORTIF (Stroke Prevention using ORal Thrombin Inhibitor in atrial Fibrillation) study, and 0 or more using those from the Danish National Patient Registry. Accounting for lower rates of NOAC-associated intracranial hemorrhage decreased optimal CHA2DS2-VASc score thresholds, but these thresholds still varied widely.

LIMITATION

Measured benefit may not generalize to other populations.

CONCLUSION

Variation in published AF stroke rates for patients not receiving anticoagulant therapy results in multifold variation in the net clinical benefit of anticoagulation. Guidelines should better reflect the uncertainty in current thresholds of stroke risk score for recommending anticoagulation.

PRIMARY FUNDING SOURCE

None.

Atrial fibrillation decision support tool: Population perspective

BACKGROUND

Appropriate thromboprophylaxis for patients with atrial fibrillation or atrial flutter (AF) remains a national challenge. The recent availability of direct oral anticoagulants (DOACs) with comparable efficacy and improved safety compared with warfarin alters the balance between risk factors for stroke and benefit of anticoagulation. Our objective was to examine the impact of DOACs as an alternative to warfarin on the net benefit of oral anticoagulant therapy (OAT) in a real-world population of AF patients.

METHODS

This is a retrospective cohort study of patients with paroxysmal or persistent nonvalvular AF. We updated an Atrial Fibrillation Decision Support Tool (AFDST) to include DOACs as treatment options. The tool generates patient-specific recommendations based upon individual patient risk factor profiles for stroke and major bleeding using quality-adjusted life-years (QALYs) calculated for each treatment strategy by a decision analytic model. The setting included inpatient and ambulatory sites in an academic health center in the midwestern United States. The study involved 5,121 adults with nonvalvular AF seen for any ambulatory visit or inpatient hospitalization over the 1-year period (January through December 2016). Outcome measure was net clinical benefit in QALYs.

RESULTS

When DOACs are a therapeutic option, the AFDST recommends OAT for 4,134 (81%) patients and no antithrombotic therapy or aspirin for 489 (9%). A strong recommendation for OAT could not be made in 498 (10%) patients. When warfarin is the only option, OAT is recommended for 3,228 (63%) patients and no antithrombotic therapy or aspirin for 973 (19%). A strong recommendation for OAT could not be made in 920 (18%) patients. In total, 1,508 QALYs could be gained if treatment were changed to that recommended by the AFDST.

CONCLUSIONS

Availability of DOACs increases the proportion of patients for whom oral anticoagulation therapy is recommended in a real-world cohort of AF patients and increased projected QALYs by more than 1,500 when all patients are receiving thromboprophylaxis as recommended by the AFDST compared with current treatment.

Predicting Hemorrhagic Transformation of Acute Ischemic Stroke: Prospective Validation of the HeRS Score

Hemorrhagic transformation (HT) increases the morbidity and mortality of ischemic stroke. Anticoagulation is often indicated in patients with atrial fibrillation, low ejection fraction, or mechanical valves who are hospitalized with acute stroke, but increases the risk of HT. Risk quantification would be useful. Prior studies have investigated risk of systemic hemorrhage in anticoagulated patients, but none looked specifically at HT. In our previously published work, age, infarct volume, and estimated glomerular filtration rate (eGFR) significantly predicted HT. We created the hemorrhage risk stratification (HeRS) score based on regression coefficients in multivariable modeling and now determine its validity in a prospectively followed inpatient cohort.A total of 241 consecutive patients presenting to 2 academic stroke centers with acute ischemic stroke and an indication for anticoagulation over a 2.75-year period were included. Neuroimaging was evaluated for infarct volume and HT. Hemorrhages were classified as symptomatic versus asymptomatic, and by severity. HeRS scores were calculated for each patient and compared to actual hemorrhage status using receiver operating curve analysis.Area under the curve (AUC) comparing predicted odds of hemorrhage (HeRS score) to actual hemorrhage status was 0.701. Serum glucose (P < 0.001), white blood cell count (P < 0.001), and warfarin use prior to admission (P = 0.002) were also associated with HT in the validation cohort. With these variables, AUC improved to 0.854. Anticoagulation did not significantly increase HT; but with higher intensity anticoagulation, hemorrhages were more likely to be symptomatic and more severe.The HeRS score is a valid predictor of HT in patients with ischemic stroke and indication for anticoagulation.

Developing an Atrial Fibrillation Guideline Support Tool (AFGuST) for shared decision making

OBJECTIVE

Patient values and preferences are an important component to decision making when tradeoffs exist that impact quality of life, such as tradeoffs between stroke prevention and hemorrhage in patients with atrial fibrillation (AF) contemplating anticoagulant therapy. Our objective is to describe the development of an Atrial Fibrillation Guideline Support Tool (AFGuST) to assist the process of integrating patients' preferences into this decision.

MATERIALS AND METHODS

CHA2DS2VASc and HAS-BLED were used to calculate risks for stroke and hemorrhage. We developed a Markov decision analytic model as a computational engine to integrate patient-specific risk for stroke and hemorrhage and individual patient values for relevant outcomes in decisions about anticoagulant therapy.

RESULTS

Individual patient preferences for health-related outcomes may have greater or lesser impact on the choice of optimal antithrombotic therapy, depending upon the balance of patient-specific risks for ischemic stroke and major bleeding. These factors have been incorporated into patient-tailored booklets which, along with an informational video, were developed through an iterative process with clinicians and patient focus groups.

KEY LIMITATIONS

Current risk prediction models for hemorrhage, such as the HAS-BLED, used in the AFGuST, do not incorporate all potentially significant risk factors. Novel oral anticoagulant agents recently approved for use in the United States, Canada, and Europe have not been included in the AFGuST. Rather, warfarin has been used as a conservative proxy for all oral anticoagulant therapy.

CONCLUSIONS

We present a proof of concept that a patient-tailored decision-support tool could bridge the gap between guidelines and practice by incorporating individual patient's stroke and bleeding risks and their values for major bleeding events and stroke to facilitate a shared decision making process. If effective, the AFGuST could be used as an adjunct to published guidelines to enhance patient-centered conversations about the anticoagulation management.

Can we improve the early detection of atrial fibrillation in a stroke unit? Detection rate of a monitor with integrated detection software

INTRODUCTION

It is unknown whether monitors that include atrial fibrillation recognition software (AF-RS) increase the rate of early atrial fibrillation (AF) detection in acute stroke. We aimed to evaluate the AF detection rate of an AF-RS monitor and compare it with standard monitoring.

METHODS

This was a retrospective, single-centre observational study conducted on consecutive patients with acute transient ischaemic attack or brain infarction attended in a stroke unit (SU) with six beds. Five beds had a standard monitor with a three-lead electrocardiogram (ECG)-tracing monitor that did not automatically detect AF, and one bed had a 12-lead ECG monitor with integrated AF-RS. All patients were monitored for at least 24 h and underwent a daily ECG during their stay in the SU. In case of unknown stroke aetiology, the patients underwent 24 h Holter monitoring.

RESULTS

A total of 76 patients were included: 59 patients in the standard monitor group and 17 patients in the AF-RS monitor group. The mean age was 72.11 (±13.09) years, and 59.2% were men. A total of 20 new cases of AF were identified. The AF-RS monitor showed a higher rate of AF detection than the standard devices (57.1% vs 7.7%, p=0.031). The AF-RS monitor showed sensitivity, specificity, positive predictive value, and negative predictive values of 57.1%, 100%, 100% and 76.9%, respectively. For the standard monitors, these values were 7.7%, 100%, 100% and 79.3%, respectively.

CONCLUSION

The monitor with AF-RS demonstrated a higher detection rate for AF than standard ECG monitoring in acute stroke patients in a SU.

[Interventional prevention of ischemic stroke]

Stroke is an extremely common condition, the important functional and financial impact of which requires intense prevention policy. This strategy includes the prevention of thromboembolic complications of atrial fibrillation. The management of atrial fibrillation includes risk stratification for stroke with theCHA(2)DS(2)VASc score and assessment of hemorrhagic risk with HASBLED score. The reference preventive treatment is anticoagulant therapy with vitamin K antagonists. Nevertheless, many patients potentially eligible for this treatment will not benefit from it, because of a high risk of bleeding, or because recurrence of thromboembolism occurs despite well-conducted anticoagulation. A new alternative intrventional treatment has been proposed for these clinical situations: left atrial appendage percutaneous closure. Several studies examined the feasibility, effectiveness and safety of three devices: the device PLAATO the WATCHMAN(©), and AmplatzerCardiacPlug™. The prospective multicenter randomized PROTECT-AF study demonstrated non-inferiority of the WATCHMAN(©) device compared to conventional warfarin therapy. Yet a medical reflection is still needed to determine the target population which may actually benefit from interventional treatment. Currently, clinical evaluation programs have begun in France with the aim to clarify the indication of non-drug preventive treatment of stroke.

Severity of leukoaraiosis determines clinical phenotype after brain infarction

OBJECTIVE

To determine whether the extent of leukoaraiosis, a composite marker of baseline brain integrity, differed between patients with TIA with diffusion-weighted imaging (DWI) evidence of infarction (transient symptoms with infarction [TSI]) and patients with ischemic stroke.

METHODS

Leukoaraiosis volume on MRI was quantified in a consecutive series of 153 TSI and 354 ischemic stroke patients with comparable infarct volumes on DWI. We explored the relationship between leukoaraiosis volume and clinical phenotype (TIA or ischemic stroke) using a logistic regression model.

RESULTS

Patients with TSI tended to be younger (median age 66 vs 69 years, p = 0.062) and had smaller median normalized leukoaraiosis volume (1.2 mL, interquartile range [IQR] 0.2-4.7 mL vs 3.5 mL, IQR 1.2-8.6 mL, p < 0.001). In multivariable analysis controlling for age, stroke risk factors, etiologic stroke mechanism, infarct volume, and infarct location, increasing leukoaraiosis volume remained associated with ischemic stroke (odds ratio 1.05 per mL, 95%confidence interval 1.02-1.09, p = 0.004), along with infarct volume and infarct location.

CONCLUSION

The probability of ischemic stroke rather than TSI increases with increasing leukoaraiosis volume, independent of infarct size and location. Our findings support the concept that the integrity of white matter tracts connecting different parts of the brain could contribute to whether or not patients develop TSI or ischemic stroke in an event of brain infarction.

Moving the tipping point: the decision to anticoagulate patients with atrial fibrillation

BACKGROUND

The rate of ischemic stroke associated with traditional risk factors for patients with atrial fibrillation has declined over the past 2 decades. Furthermore, new and potentially safer anticoagulants are on the horizon. Thus, the balance between risk factors for stroke and benefit of anticoagulation may be shifting.

METHODS AND RESULTS

The Markov state transition decision model was used to analyze the CHADS(2) score, above which anticoagulation is preferred, first using the stroke rate predicted for the CHADS(2) derivation cohort, and then using the stroke rate from the more contemporary AnTicoagulation and Risk Factors In Atrial Fibrillation cohort for any CHADS(2) score. The base case was a 69-year-old man with atrial fibrillation. Interventions included oral anticoagulant therapy with warfarin or a hypothetical "new and safer" anticoagulant (based on dabigatran), no antithrombotic therapy, or aspirin. Warfarin is preferred above a stroke rate of 1.7% per year, whereas aspirin is preferred at lower rates of stroke. Anticoagulation with warfarin is preferred even for a score of 0 using the higher rates of the older CHADS(2) derivation cohort. Using more contemporary and lower estimates of stroke risk raises the threshold for use of warfarin to a CHADS(2) score ≥2. However, anticoagulation with a "new, safer" agent, modeled on the results of the Randomized Evaluation of Long-Term Anticoagulation Therapy trial of dabigatran, leads to a lowering of the threshold for anticoagulation to a stroke rate of 0.9% per year.

CONCLUSIONS

Use of a more contemporary estimate of stroke risk shifts the "tipping point," such that anticoagulation is preferred at a higher CHADS(2) score, reducing the number of patients for whom anticoagulation is recommended. The introduction of "new, safer" agents, however, would shift the tipping point in the opposite direction.

Should we test for CYP2C9 before initiating anticoagulant therapy in patients with atrial fibrillation?

BACKGROUND

Genetic variants of the warfarin sensitivity gene CYP2C9 have been associated with increased bleeding risk during warfarin initiation. Studies also suggest that such patients remain at risk throughout treatment.

OBJECTIVE

Would testing patients with non-valvular atrial fibrillation (AF) for CYP2C9 before initiating warfarin improve outcomes?

DESIGN

Markov state transition decision model.

SETTING

Ambulatory or inpatient settings necessitating new initiation of anticoagulation.

PATIENTS

The base case was a 69-year-old man with newly diagnosed non-valvular AF. Interventions included: (1) warfarin, (2) aspirin, or (3) no antithrombotic therapy without genetic testing; and genetic testing followed by (4) aspirin or (5) no antithrombotic therapy in those with culprit CYP2C9 alleles.

MEASURES

Quality-adjusted life years (QALYs).

RESULTS

In the base case, testing and treating patients with CYP2C9*2 and/or CYP2C9*3 with aspirin rather than warfarin was best (8.97 QALYs). However, warfarin without genetic testing was a close second (8.96 QALYs), a difference of roughly 5 days. Sensitivity analyses demonstrated that genetic testing followed by aspirin was best for patients at lower risk of embolic events. Warfarin without testing was preferred if the rate of embolic events was greater than 5% per year, or the risk of major bleeding while receiving warfarin was lower.

CONCLUSION

For patients at average risk for ischemic stroke due to AF and at average risk for major hemorrhage, treatment based on genetic testing offers no benefit compared to warfarin initiation without testing. The gain from testing may be larger in patients at lower risk of embolic events or at greater risk of bleeding.

Patient-specific decision-making for warfarin therapy in nonvalvular atrial fibrillation: how will screening with genetics and imaging help?

BACKGROUND AND PURPOSE

Intracerebral hemorrhage (ICH) accounts for a majority of long-term morbidity and mortality associated with bleeding while on warfarin. Both ICH and warfarin-related ICH appear to have a genetic component. Furthermore, advanced neuroimaging using MRI can now identify individuals at increased risk of ICH. We explore whether screening strategies that include genetic profiling and neuroimaging might improve the safety of chronic anticoagulation for atrial fibrillation by identifying individuals from whom warfarin should be withheld.

METHODS

We used a Markov state transition decision model. Effectiveness was measured in quality-adjusted life-years. Data sources included the English language literature using MEDLINE searches and bibliographies from selected articles along with empirical data from our institutions. The base case was a 69-year-old man with newly diagnosed nonvalvular atrial fibrillation.

RESULTS

For patients at average risk for thromboembolic events and known to possess a hypothetical genetic profile increasing risk for warfarin ICH, anticoagulation remains the preferred strategy until the relative hazard of ICH exceeds 23.8. Genetic profiling would be favored for patients at low risk of thromboembolism (1.5% per year) if the hypothetical gene variant(s) conferred a relative risk of ICH >4.1. Screening strategies in which patients underwent genotyping and MRI before anticoagulation did not improve aggregate patient outcomes unless the predictive power of MRI exceeded current best guess estimates and patients were at low to moderate risk of thromboembolism.

CONCLUSIONS

Currently identified genetic markers of bleeding risk do not confer a risk of ICH sufficiently high to warrant routine genetic testing for patients at average risk of thromboembolism. Even if patients undergo screening with MRI as well as genotyping, currently available data on the role of MRI on risk of ICH and warfarin ICH do not support use of these tests for withholding anticoagulation in patients with atrial fibrillation.

Optimising stroke prevention in non-valvular atrial fibrillation

Atrial fibrillation is associated with substantial morbidity and mortality. Pooled data from trials comparing antithrombotic treatment with placebo have shown that warfarin reduces the risk of stroke by 62%, and that aspirin alone reduces the risk by 22%. Overall, in high-risk patients, warfarin is superior to aspirin in preventing strokes, with a relative risk reduction of 36%. Ximelagatran, an oral direct thrombin inhibitor, was found to be as efficient as vitamin K antagonist drugs in the prevention of embolic events, but has been recently withdrawn because of abnormal liver function tests. The ACTIVE-W (Atrial Fibrillation Clopidogrel Trial with Irbesartan for Prevention of Vascular Events) study has demonstrated that warfarin is superior to platelet therapy (clopidogrel plus aspirin) in the prevention af embolic events. Idraparinux, a Factor Xa inhibitor, is being evaluated in patients with atrial fibrillation. Angiotensin-converting enzyme inhibitors and angiotensin II receptor-blocking drugs hold promise in atrial fibrillation through cardiac remodelling. Preliminary studies suggest that statins could interfere with the risk of recurrence after electrical cardioversion. Finally, percutaneous methods for the exclusion of left atrial appendage are under investigation in high-risk patients.

Frequency and effect of optimal anticoagulation before onset of ischaemic stroke in patients with known atrial fibrillation

BACKGROUND

The aims of the study were (i) to examine which antithrombotic therapy patients with known atrial fibrillation use at the point of time when they suffer an ischaemic stroke, (ii) to evaluate the effects of optimal antithrombotic treatment on outcome and severity of the stroke.

METHODS

Patients with known atrial fibrillation before onset of acute ischaemic stroke, and age >60 years were included. Antithrombotic therapy on admission was classified into four groups: no antithrombotic therapy, aspirin, sub-optimal anticoagulation (warfarin and international normalized ratio, INR<2.0) and optimal anticoagulation (warfarin and INR>or=2.0).

PRIMARY OUTCOME

modified Rankin Scale (mRS) 5 or 6 at day 7 poststroke.

SECONDARY OUTCOMES

(i) death or discharge to a nursing home, (ii) death, (iii) stroke severity on admission assessed by Scandinavian Stroke Scale.

RESULTS

A total of 394 patients were included. On admission 109 (28%) patients used no antithrombotic therapy, 169 (43%) aspirin, 52 (13%) warfarin and had an INR<2.0, and 64 (16%) used warfarin and had an INR>or=2.0. The proportion of patients with an mRS 5 or 6 and the corresponding odds ratios were: in the warfarin group with INR<2.0, 16 (31%), OR 3.1 (CI: 1.2-8.0), (P=0.019), in the group with no antithrombotic therapy 29 (27%), 2.5 (1.1-5.9), (P=0.034), and in the aspirin group 41(24%), 2.2 (1.0-5.1) (P=0.054), compared with the warfarin group with INR>or=2.0, where eight (13%) patients had a poor outcome. A significantly higher proportion of patients died or were discharged to a nursing home in the warfarin group with an INR<2.0 (P=0.014), in the aspirin group (P=0.018) and in the no-treatment group (P=0.035), compared with the warfarin group with an INR>or=2.0. No significant differences were found regarding death alone and stroke severity on admission.

DISCUSSION

Few patients with known atrial fibrillation who suffer an ischaemic stroke receive optimal antithrombotic therapy prior to the onset of stroke. Optimal anticoagulation does not only reduce the risk of ischaemic stroke, but also appears to reduce death and severe dependency as well as the need for nursing home care, if an ischaemic stroke occurs.

Detection of atrial fibrillation in patients with acute stroke

Atrial fibrillation (AF) and paroxysmal AF (PAF) are common causes of stroke which may not be detected by a single electrocardiogram (EKG). We conducted a prospective study to determine if 48 hours of telemetry monitoring increased the rate of detection of AF in patients with acute stroke and thus identified patients requiring anticoagulation. One hundred and fifty consecutive patients with acute ischemic stroke were placed on telemetry monitoring for 48 hours. Thirty-five patients had AF related strokes. There were 12 patients with AF related stroke who did not have a previous history of AF and were found to have AF following the stroke. Six of these 12 patients were found to have AF on their admission EKG. The remaining six patients had normal admission EKGs and were diagnosed with AF only during telemetry monitoring for 48 hrs. Patients with AF were older, had larger strokes, which were more likely to be non-lacunar, than patients without AF. Our study suggests that AF is sometimes undiagnosed until a stroke occurs. Improved methods of detection of AF are needed in high-risk patients for primary stroke prevention. Patients older than 65 years of age with non-lacunar strokes should have 48 hours of telemetry monitoring to detect previously undiagnosed AF.

Effect of intensity of oral anticoagulation on stroke severity and mortality in atrial fibrillation

BACKGROUND

The incidence of stroke in patients with atrial fibrillation is greatly reduced by oral anticoagulation, with the full effect seen at international normalized ratio (INR) values of 2.0 or greater. The effect of the intensity of oral anticoagulation on the severity of atrial fibrillation-related stroke is not known but is central to the choice of the target INR.

METHODS

We studied incident ischemic strokes in a cohort of 13,559 patients with nonvalvular atrial fibrillation. Strokes were identified through hospitalization data bases and validated on the basis of medical records, which also provided information on the use of warfarin or aspirin, the INR at admission, and coexisting illnesses. The severity of stroke was graded according to a modified Rankin scale. Thirty-day mortality was ascertained from hospitalization and mortality files.

RESULTS

Of 596 ischemic strokes, 32 percent occurred during warfarin therapy, 27 percent during aspirin therapy, and 42 percent during neither type of therapy. Among patients who were taking warfarin, an INR of less than 2.0 at admission, as compared with an INR of 2.0 or greater, independently increased the odds of a severe stroke in a proportional-odds logistic-regression model (odds ratio, 1.9; 95 percent confidence interval, 1.1 to 3.4) across three severity categories and the risk of death within 30 days (hazard ratio, 3.4; 95 percent confidence interval, 1.1 to 10.1). An INR of 1.5 to 1.9 at admission was associated with a mortality rate similar to that for an INR of less than 1.5 (18 percent and 15 percent, respectively). The 30-day mortality rate among patients who were taking aspirin at the time of the stroke was similar to that among patients who were taking warfarin and who had an INR of less than 2.0.

CONCLUSIONS

Among patients with nonvalvular atrial fibrillation, anticoagulation that results in an INR of 2.0 or greater reduces not only the frequency of ischemic stroke but also its severity and the risk of death from stroke. Our findings provide further evidence against the use of lower INR target levels in patients with atrial fibrillation.

Can patients be anticoagulated after intracerebral hemorrhage? A decision analysis

BACKGROUND AND PURPOSE

Warfarin increases both the likelihood and the mortality of intracerebral hemorrhage (ICH), particularly in patients with a history of prior ICH. In light of this consideration, should a patient with both a history of ICH and a clear indication for anticoagulation such as nonvalvular atrial fibrillation be anticoagulated? In the absence of data from a clinical trial, we used a decision-analysis model to compare the expected values of 2 treatment strategies-warfarin and no anticoagulation-for such patients.

METHODS

We used a Markov state transition decision model stratified by location of hemorrhage (lobar or deep hemispheric). Effectiveness was measured in quality-adjusted life years (QALYs). Data sources included English language literature identified through MEDLINE searches and bibliographies from selected articles, along with empirical data from our own institution. The base case focused on a 69-year-old man with a history of ICH and newly diagnosed nonvalvular atrial fibrillation.

RESULTS

For patients with prior lobar ICH, withholding anticoagulation therapy was strongly preferred, improving quality-adjusted life expectancy by 1.9 QALYs. For patients with prior deep hemispheric ICH, withholding anticoagulation resulted in a smaller gain of 0.3 QALYs. In sensitivity analyses for patients with deep ICH, anticoagulation could be preferred if the risk of thromboembolic stroke is particularly high.

CONCLUSIONS

Survivors of lobar ICH with atrial fibrillation should not be offered long-term anticoagulation. Similarly, most patients with deep hemispheric ICH and atrial fibrillation should not receive anticoagulant therapy. However, patients with deep hemispheric ICH at particularly high risk for thromboembolic stroke or low risk of ICH recurrence might benefit from long-term anticoagulation.