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## Complete Summary

#### GUIDELINE TITLE

Practice parameter: recurrent stroke with patent foramen ovale and
atrial septal aneurysm: report of the Quality Standards Subcommittee of
the American Academy of Neurology.

#### BIBLIOGRAPHIC SOURCE(S)

Messe SR, Silverman IE, Kizer JR, Homma S, Zahn C, Gronseth G, Kasner
SE. Practice parameter: recurrent stroke with patent foramen ovale and
atrial septal aneurysm: report of the Quality Standards Subcommittee of
the American Academy of Neurology. Neurology 2004 Apr 13;62(7):1042-50.
\[37 references\]
[PubMed](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15078999)

#### GUIDELINE STATUS

This is the current release of the guideline.

### \*\* REGULATORY ALERT \*\*

#### FDA WARNING/REGULATORY ALERT

**Note from the National Guideline Clearinghouse**: This guideline
references a drug(s) for which important revised regulatory and/or
warning information has been released.

-   [August 16, 2007, Coumadin
    (Warfarin)](http://www.fda.gov/medwatch/safety/2007/safety07.htm#Warfarin):
    Updates to the labeling for Coumadin to include pharmacogenomics
    information to explain that people\'s genetic makeup may influence
    how they respond to the drug.

-   [October 6, 2006, Coumadin (warfarin
    sodium)](http://www.fda.gov/medwatch/safety/2006/safety06.htm#Coumadin):
    Revisions to the labeling for Coumadin to include a new patient
    Medication Guide as well as a reorganization and highlighting of the
    current safety information to better inform providers and patients.

### COMPLETE SUMMARY CONTENT

 \*\* REGULATORY ALERT \*\*\
 SCOPE\
 METHODOLOGY - including Rating Scheme and Cost Analysis\
 RECOMMENDATIONS\
 EVIDENCE SUPPORTING THE RECOMMENDATIONS\
 BENEFITS/HARMS OF IMPLEMENTING THE GUIDELINE RECOMMENDATIONS\
 QUALIFYING STATEMENTS\
 IMPLEMENTATION OF THE GUIDELINE\
 INSTITUTE OF MEDICINE (IOM) NATIONAL HEALTHCARE QUALITY REPORT
CATEGORIES\
 IDENTIFYING INFORMATION AND AVAILABILITY\
 DISCLAIMER

### SCOPE

#### DISEASE/CONDITION(S)

-   Stroke

-   Patent foramen ovale (PFO)

-   Atrial septal aneurysm (ASA)

#### GUIDELINE CATEGORY

Assessment of Therapeutic Effectiveness\
Prevention\
Risk Assessment\
Treatment

#### CLINICAL SPECIALTY

Cardiology\
Neurology

#### INTENDED USERS

Physicians

#### GUIDELINE OBJECTIVE(S)

-   To evaluate the risk of subsequent stroke or death in patients with
    a cryptogenic stroke and a patent foramen ovale (PFO), atrial septal
    aneurysm (ASA), or both

-   To establish the optimal method of stroke prevention in this
    population of patients

#### TARGET POPULATION

Patients with a cryptogenic stroke and a patent foramen ovale (PFO),
atrial septal aneurysm (ASA), or both

#### INTERVENTIONS AND PRACTICES CONSIDERED

**Prevention/Treatment**

1.  Aspirin

2.  Warfarin

**Note**: There is insufficient evidence regarding the effectiveness of
either surgical or percutaneous closure of patent foramen ovale (PFO).

#### MAJOR OUTCOMES CONSIDERED

-   Incidence of recurrent stroke

-   Death

-   Incidences of major and minor bleeding complications

### METHODOLOGY

#### METHODS USED TO COLLECT/SELECT EVIDENCE

Hand-searches of Published Literature (Primary Sources)\
Hand-searches of Published Literature (Secondary Sources)\
Searches of Electronic Databases

#### DESCRIPTION OF METHODS USED TO COLLECT/SELECT THE EVIDENCE

**Identification and selection of studies**

Literature searches were performed using the following keywords and
search paradigm: (\"stroke\" *or* \"CVA\" *or* \"cerebrovascular
disease\") *and* (\"PFO\" *or* \"patent foramen ovale\" *or* \"atrial
septal defect\" *or* \"atrial septal aneurysm\") *and* (\"aspirin\" *or*
\"anti-platelet\" *or* \"warfarin\" *or* \"anticoagulation\" *or*
\"closure\"). This search was applied to the following databases on June
24, 2002: the National Library of Medicine\'s Pub Med search engine,
which includes citations from 1966 through June 2002; the Cochrane
database of systematic reviews; abstracts from the American Heart
Association Stroke meetings, 1997--2002; and abstracts from American
Academy of Neurology meetings, 1997--2002.

The resulting articles and their references were screened using the
inclusion and exclusion criteria described in a table in the original
guideline document. Specifically, the Quality Standards Subcommittee
(QSS) selected randomized-controlled trials (RCT) or prospective cohort
studies that made one of two comparisons:

-   Event rates in patients with cryptogenic stroke and atrial septal
    abnormalities versus patients with a cryptogenic stroke and no
    atrial septal abnormality

-   Event rates in patients with cryptogenic stroke and atrial septal
    abnormalities who received different treatments

The QSS chose to limit their analysis to RCT and prospective cohort
studies for a number of reasons. First, retrospective studies for this
type of clinical question have tremendous potential for bias that
significantly degrades their validity. For example, in studies that are
retrospective or nonrandomized, the largest PFO would likely be
considered more strongly for closure or warfarin therapy while the
smallest PFO might be treated with aspirin (i.e., confounding by
indication). Second, every one of the therapeutic interventions that are
used in this patient population has the potential for significant
adverse effects. Thus, the QSS used the strictest, most conservative
criteria for inclusion in their analysis in order to make the most valid
recommendation possible.

#### NUMBER OF SOURCE DOCUMENTS

The literature search produced a list of 129 articles, of which only
four fulfilled all of the inclusion and exclusion criteria.

#### METHODS USED TO ASSESS THE QUALITY AND STRENGTH OF THE EVIDENCE

Weighting According to a Rating Scheme (Scheme Given)

#### RATING SCHEME FOR THE STRENGTH OF THE EVIDENCE

**Rating of Therapeutic Article**

**Class I**: Prospective, randomized, controlled clinical trial (RCT)
with masked outcome assessment, in a representative population. The
following are required:

a.  Primary outcome(s) is/are clearly defined.

b.  Exclusion/inclusion criteria are clearly defined.

c.  Adequate accounting for dropouts and crossovers with numbers
    sufficiently low to have minimal potential for bias.

d.  Relevant baseline characteristics are presented and substantially
    equivalent among treatment groups or there is appropriate
    statistical adjustment for differences.

**Class II**: Prospective matched group cohort study in a representative
population with masked outcome assessment that meets a--d above OR an
RCT in a representative population that lacks one criteria a--d.

**Class III**: All other controlled trials (including well-defined
natural history controls or patients serving as own controls) in a
representative population, where outcome is independently assessed, or
independently derived by objective outcome measurement.

**Class IV**: Evidence from uncontrolled studies, case series, case
reports, or expert opinion.

**Note**: Objective outcome measurement -- an outcome measure that is
unlikely to be affected by an observer\'s (patient, treating physician,
investigator) expectation or bias (e.g., blood tests, administrative
outcome data).

**Rating of Prognostic Article**

**Class I**: Evidence provided by a prospective study of a broad
spectrum of persons who may be at risk for developing the outcome (e.g.,
target disease, work status). The study measures the predictive ability
using an independent gold standard for case definition. The predictor is
measured in an evaluation that is masked to clinical presentation and
the outcome is measured in an evaluation that is masked to the presence
of the predictor.

**Class II**: Evidence provided by a prospective study of a narrow
spectrum of persons at risk for having the condition, or by a
retrospective study of a broad spectrum of persons with the condition
compared to a broad spectrum of controls. The study measures the
prognostic accuracy of the risk factor using an acceptable independent
gold standard for case definition. The risk factor is measured in an
evaluation that is masked to the outcome.

**Class III**: Evidence provided by a retrospective study where either
the persons with the condition or the controls are of a narrow spectrum.
The study measures the predictive ability using an acceptable
independent gold standard for case definition. The risk factor is
measured in an evaluation that is masked to the outcome.

**Class IV**: Any design where the predictor is not applied in a masked
evaluation OR evidence provided by expert opinion or case series without
controls.

#### METHODS USED TO ANALYZE THE EVIDENCE

Meta-Analysis of Randomized Controlled Trials\
Systematic Review with Evidence Tables

#### DESCRIPTION OF THE METHODS USED TO ANALYZE THE EVIDENCE

**Data Extraction and Grading the Evidence**

The articles that met the inclusion and exclusion criteria were
evaluated by each of the authors. For each of the clinical questions,
the selected articles were graded for potential bias according to the
classification-of-evidence scheme described above in the \"Rating Scheme
for the Strength of the Evidence in Appendix\" field (a given article
may have received different grades for each question depending on the
methods employed). As noted in previous practice parameters, class I
evidence is expected to have the lowest risk of bias, while class IV
evidence is judged to have a high risk of bias. The authors rated each
study independently and resolved any discrepancies later. Outcome data
were organized into a data extraction table (please refer to Appendix 2
of the original guideline document).

**Measures of Recurrent Stroke Risk and Therapeutic Effect**

The primary outcome was recurrent stroke or death. In order to determine
the risk associated with the presence of an atrial septal abnormality
the Quality Standards Subcommittee (QSS) compared the proportion of
patients who had a stroke or death in the group of patients with atrial
septal abnormalities to the group of patients without such
abnormalities. The QSS then calculated the relative risks (RR) using the
formula:

RR = \[A/(A+C)\]/\[B/(B+D)\]

  -----------------------------------------------------------------------
  ** **                          **Stroke or        **No stroke or
                                 death**            death**
  ------------------------------ ------------------ ---------------------
  **Atrial septal abnormality**  A                  C

  **No atrial septal             B                  D
  abnormality**                                     
  -----------------------------------------------------------------------

Similarly, the QSS compared the RR of stroke or death for each of the
available therapies using aspirin as the reference. When appropriate,
the QSS selectively pooled the data from comparable studies using
general variance-based meta-analytic techniques. The QSS determined 95%
confidence intervals for all calculations. Final recommendations are
graded according to the scheme described below in the \"Rating Scheme
for the Strength of the Recommendations\" field.

#### METHODS USED TO FORMULATE THE RECOMMENDATIONS

Other

#### DESCRIPTION OF METHODS USED TO FORMULATE THE RECOMMENDATIONS

When formulating the recommendations the guideline developers considered
the *magnitude* of the effect (benefit or harm of therapy, accuracy of
tests, yield of studies) and the relative *value* of various outcomes.
Under most circumstances, there is a direct link between the level of
evidence used to formulate conclusions and the strength of the
recommendation. This linkage is illustrated in Appendix 9 of the 2004
AAN Guideline Process Manual (see Companion Documents field). Thus, an
\"established as\" (two class I) conclusion supports a \"should be
done\" (level A) recommendation; a \"probably effective\" (two class II)
conclusion supports a \"should be considered\" (level B) recommendation;
a \"possibly effective\" (two class III) conclusion supports a \"may be
considered\" recommendation. In those circumstances where the evidence
indicates that the intervention is not effective or useful, wording was
modified. For example, if multiple adequately powered class I studies
demonstrated that an intervention is not effective, the recommendation
read, \"should not be done.\"

There are important exceptions to the rule of having a direct linkage
between the level of evidence and the strength of recommendations. Some
situations where it may be necessary to break this linkage are listed
below:

-   A statistically significant but marginally important benefit of the
    intervention is observed

-   The intervention is exorbitantly costly

-   Superior and established alternative interventions are available

-   There are competing outcomes (both beneficial and harmful) that
    cannot be reconciled

Under such circumstances the guideline developers may have downgraded
the level of the recommendation.

Edlund W, Gronseth G, So Y, Franklin G. Clinical practice guideline
process manual. St. Paul (MN): American Academy of Neurology (AAN);
2004. 49 p.

#### RATING SCHEME FOR THE STRENGTH OF THE RECOMMENDATIONS

**Rating of Recommendations**

**A** = Established as effective, ineffective, or harmful for the given
condition in the specified population.

**B** = Probably effective, ineffective, or harmful for the given
condition in the specified population.

**C** = Possibly effective, ineffective, or harmful for the given
condition in the specified population.

**U** = Data inadequate or conflicting. Given current knowledge,
treatment (test, predictor) is unproven.

**Translation of Evidence to Recommendation**

**Level A** rating requires at least two consistent Class I studies\*.

**Level B** rating requires at least one Class I study or two consistent
Class II studies.

**Level C** rating requires at least one Class II study or two
consistent class III studies.

**Level U** rating for studies not meeting criteria for class I-- class
III.

\***Note**: In exceptional cases, one *convincing* Class I study may
suffice for an \"A\" recommendation if 1) all criteria met, 2) magnitude
of effect [\>]{.underline}5, and 3) narrow confidence intervals (lower
limit \>2).

#### COST ANALYSIS

A formal cost analysis was not performed and published cost analyses
were not reviewed.

#### METHOD OF GUIDELINE VALIDATION

External Peer Review\
Internal Peer Review

#### DESCRIPTION OF METHOD OF GUIDELINE VALIDATION

Guidelines were approved by the Quality Standards Subcommittee in July
2003, the American Academy of Neurology (AAN) in October 2003, and the
AAN Board of Directors in January 2004.

### RECOMMENDATIONS

#### MAJOR RECOMMENDATIONS

Definitions of the strength of the recommendations (A, B, C, U) and
classification of the evidence (Class I through Class IV) are provided
at the end of the \"Major Recommendations\" field.

**Practice Recommendations**

For patients who have had a cryptogenic stroke and have a patent foramen
ovale (PFO), the evidence indicates that the risk of subsequent stroke
or death is no different from other cryptogenic stroke patients without
PFO when treated medically with antiplatelet agents or anticoagulants.
Therefore, in persons with a cryptogenic stroke receiving such therapy,
neurologists should communicate to patients and their families that
presence of PFO does not confer an increased risk for subsequent stroke
compared to other cryptogenic stroke patients without atrial
abnormalities (**Level A**). However, it is possible that the
combination of PFO and atrial septal aneurysm (ASA) confers an increased
risk of subsequent stroke in medically treated patients who are less
than 55 years of age. Therefore, in younger stroke patients, studies
that can identify PFO or atrial septal aneurysm (ASA) may be considered
for prognostic purposes (**Level C**).

Among patients with a cryptogenic stroke and atrial septal
abnormalities, there is insufficient evidence to determine the
superiority of aspirin or warfarin for prevention of recurrent stroke or
death (**Level U**), but the risks of minor bleeding are possibly
greater with warfarin (**Level C**). There is insufficient evidence
regarding the effectiveness of either surgical or percutaneous closure
of PFO (**Level U**).

**[Definitions]{.underline}**:

**Rating of Recommendations**

**A** = Established as effective, ineffective, or harmful for the given
condition in the specified population.

**B** = Probably effective, ineffective, or harmful for the given
condition in the specified population.

**C** = Possibly effective, ineffective, or harmful for the given
condition in the specified population.

**U** = Data inadequate or conflicting. Given current knowledge,
treatment (test, predictor) is unproven.

**Translation of Evidence to Recommendation**

**Level A** rating requires at least two consistent Class I studies\*.

**Level B** rating requires at least one Class I study or two consistent
Class II studies.

**Level C** rating requires at least one Class II study or two
consistent class III studies.

**Level U** rating for studies not meeting criteria for class I-- class
III.

\***Note**: In exceptional cases, one *convincing* Class I study may
suffice for an \"A\" recommendation if 1) all criteria met, 2) magnitude
of effect [\>]{.underline}5, and 3) narrow confidence intervals (lower
limit \>2).

**Rating of Therapeutic Article**

**Class I**: Prospective, randomized, controlled clinical trial (RCT)
with masked outcome assessment, in a representative population. The
following are required:

a.  Primary outcome(s) is/are clearly defined.

b.  Exclusion/inclusion criteria are clearly defined.

c.  Adequate accounting for dropouts and crossovers with numbers
    sufficiently low to have minimal potential for bias.

d.  Relevant baseline characteristics are presented and substantially
    equivalent among treatment groups or there is appropriate
    statistical adjustment for differences.

**Class II**: Prospective matched group cohort study in a representative
population with masked outcome assessment that meets a--d above OR an
RCT in a representative population that lacks one criteria a--d.

**Class III**: All other controlled trials (including well-defined
natural history controls or patients serving as own controls) in a
representative population, where outcome is independently assessed, or
independently derived by objective outcome measurement.

**Class IV**: Evidence from uncontrolled studies, case series, case
reports, or expert opinion.

**Note**: Objective outcome measurement -- an outcome measure that is
unlikely to be affected by an observer\'s (patient, treating physician,
investigator) expectation or bias (e.g., blood tests, administrative
outcome data).

**Rating of Prognostic Article**

**Class I**: Evidence provided by a prospective study of a broad
spectrum of persons who may be at risk for developing the outcome (e.g.,
target disease, work status). The study measures the predictive ability
using an independent gold standard for case definition. The predictor is
measured in an evaluation that is masked to clinical presentation and
the outcome is measured in an evaluation that is masked to the presence
of the predictor.

**Class II**: Evidence provided by a prospective study of a narrow
spectrum of persons at risk for having the condition, or by a
retrospective study of a broad spectrum of persons with the condition
compared to a broad spectrum of controls. The study measures the
prognostic accuracy of the risk factor using an acceptable independent
gold standard for case definition. The risk factor is measured in an
evaluation that is masked to the outcome.

**Class III**: Evidence provided by a retrospective study where either
the persons with the condition or the controls are of a narrow spectrum.
The study measures the predictive ability using an acceptable
independent gold standard for case definition. The risk factor is
measured in an evaluation that is masked to the outcome.

**Class IV**: Any design where the predictor is not applied in a masked
evaluation OR evidence provided by expert opinion or case series without
controls.

#### CLINICAL ALGORITHM(S)

None provided

### EVIDENCE SUPPORTING THE RECOMMENDATIONS

#### TYPE OF EVIDENCE SUPPORTING THE RECOMMENDATIONS

The type of supporting evidence is identified and graded for each
recommendation (see \"Major Recommendations\").

### BENEFITS/HARMS OF IMPLEMENTING THE GUIDELINE RECOMMENDATIONS

#### POTENTIAL BENEFITS

Optimal management of patients who have an atrial septal abnormality and
have already had a stroke

#### POTENTIAL HARMS

One class II and one class III study demonstrated an increased risk of
minor bleeding with warfarin compared to aspirin.

### QUALIFYING STATEMENTS

#### QUALIFYING STATEMENTS

-   There were a number of potential limitations in the interpretation
    of the existing prospective data. In all studies, patients with
    cryptogenic strokes without patent foramen ovale (PFO) or atrial
    septal aneurysm (ASA) served as controls, but these patients may be
    at increased risk of subsequent stroke or death compared to the
    general population as they may harbor other undefined abnormalities
    or risk factors for stroke. If this conjecture is true, then such a
    comparison may inaccurately lead to the conclusion that there is no
    attributable risk associated with patent foramen ovale (PFO). At
    present, no other suitable prospective control population exists,
    since comparison with normal healthy subjects would be
    inappropriate. Finally, there were relatively few endpoints in these
    studies, which limited the power to reveal associations if they
    exist.

-   This statement is provided as an educational service of the American
    Academy of Neurology (AAN). It is based on an assessment of current
    scientific and clinical information. It is not intended to include
    all possible proper methods of care for a particular neurologic
    problem or all legitimate criteria for choosing to use a specific
    procedure. Neither is it intended to exclude any reasonable
    alternative methodologies. The AAN recognizes that specific patient
    care decisions are the prerogative of the patient and the physician
    caring for the patient, based on all of the circumstances involved.

### IMPLEMENTATION OF THE GUIDELINE

#### DESCRIPTION OF IMPLEMENTATION STRATEGY

An implementation strategy was not provided.

#### IMPLEMENTATION TOOLS

Personal Digital Assistant (PDA) Downloads\
Quick Reference Guides/Physician Guides\
Slide Presentation

For information about
[availability](#identifying-information-and-availability), see the
\"Availability of Companion Documents\" and \"Patient Resources\" fields
below.

### INSTITUTE OF MEDICINE (IOM) NATIONAL HEALTHCARE QUALITY REPORT CATEGORIES

#### IOM CARE NEED

Living with Illness\
Staying Healthy

#### IOM DOMAIN

Effectiveness

### IDENTIFYING INFORMATION AND AVAILABILITY

#### BIBLIOGRAPHIC SOURCE(S)

Messe SR, Silverman IE, Kizer JR, Homma S, Zahn C, Gronseth G, Kasner
SE. Practice parameter: recurrent stroke with patent foramen ovale and
atrial septal aneurysm: report of the Quality Standards Subcommittee of
the American Academy of Neurology. Neurology 2004 Apr 13;62(7):1042-50.
\[37 references\]
[PubMed](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15078999)

#### ADAPTATION

Not applicable: The guideline was not adapted from another source.

#### DATE RELEASED

2004 Apr 13

#### GUIDELINE DEVELOPER(S)

American Academy of Neurology - Medical Specialty Society

#### SOURCE(S) OF FUNDING

American Academy of Neurology (AAN)

#### GUIDELINE COMMITTEE

Quality Standards Subcommittee of the American Academy of Neurology

#### COMPOSITION OF GROUP THAT AUTHORED THE GUIDELINE

*AAN Quality Standards Subcommittee Members*: Gary Franklin, MD, MPH
(*co-chair*); Gary Gronseth, MD (*co-chair*); Charles Argoff, MD;
Christopher Bever, Jr., MD; Jody Corey-Bloom, MD, PhD; John England, MD;
Gary Friday, MD; Michael Glantz, MD; Deborah Hirtz, MD; Donald Iverson,
MD; David Thurman, MD; Samuel Weibe, MD; William Weiner, MD; Stephen
Ashwal, MD (*ex-officio*); Jacqueline French, MD (*ex-officio*);
Catherine Zahn, MD (*ex-officio*)

#### FINANCIAL DISCLOSURES/CONFLICTS OF INTEREST

Not stated

#### GUIDELINE STATUS

This is the current release of the guideline.

#### GUIDELINE AVAILABILITY

Electronic copies: A list of American Academy of Neurology (AAN)
guidelines, along with a link to a Portable Document Format (PDF) file
for this guideline, is available at the [AAN Web
site](http://aan.com/go/practice/guidelines).

Print copies: Available from the AAN Member Services Center, (800)
879-1960, or from AAN, 1080 Montreal Avenue, St. Paul, MN 55116.

#### AVAILABILITY OF COMPANION DOCUMENTS

The following are available:

-   Recurrent stroke in patients with patent foramen ovale and atrial
    septal aneurysm. AAN guideline summary for clinicians. St. Paul
    (MN): American Academy of Neurology. 2. p. Available in Portable
    Document Format (PDF) from the [American Academy of Neurology (AAN)
    Web
    site](http://www.aan.com/professionals/practice/pdfs/Clinician_Stroke_D3.pdf).

-   Practice parameter: recurrent stroke with patent foramen ovale and
    atrial septal aneurysm. St. Paul (MN): American Academy of
    Neurology. 2004. 13 p. Available for personal digital assistant
    (PDA) download from the [AAN Web
    site](http://www.aan.com/professionals/practice/guidelines/pda/Stroke_PFO.pdf).

-   Slide presentation: practice parameter: risk of recurrent stroke and
    secondary stroke prevention in patients with interatrial septal
    abnormalities (an evidence-based review). St. Paul (MN): American
    Academy of Neurology. 2004. Available in Power Point from the [AAN
    Web
    site](http://www.aan.com/about/sections/ppt/stroke_PFO_ed_slides.ppt).

-   AAN guideline development process \[online\]. St. Paul (MN):
    American Academy of Neurology (AAN). Available from the [AAN Web
    site](http://aan.com/go/practice/guidelines/development).

-   Edlund W, Gronseth G, So Y, Franklin G. Clinical practice guideline
    process manual. St. Paul (MN): American Academy of Neurology
    (AAN); 2004. 49 p. Electronic copies available in Portable Document
    Format (PDF) from the [AAN Web
    site](http://aan.com/globals/axon/assets/2535.pdf).

#### PATIENT RESOURCES

None available

#### NGC STATUS

This NGC summary was completed by ECRI on August 17, 2004. The
information was verified by the guideline developer on September 9,
2004. This summary was updated by ECRI on March 6, 2007 following the
U.S. Food and Drug Administration (FDA) advisory on Coumadin (warfarin
sodium). This summary was updated by ECRI Institute on September 7, 2007
following the revised U.S. Food and Drug Administration (FDA) advisory
on Coumadin (warfarin).

#### COPYRIGHT STATEMENT

This NGC summary is based on the original guideline, which is
copyrighted by the American Academy of Neurology.

### DISCLAIMER

#### NGC DISCLAIMER

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Date Modified: 11/3/2008