Circulation. 2000;101:e210
(Circulation. 2000;101:e210.)
© 2000 American Heart Association, Inc.
Circulation Electronic Pages |
Paradoxical Embolism as a Principal Cause of Stroke in Atrial Septal Aneurysm
Tsung O. Cheng, MD
Professor of Medicine George Washington University,
Washington, DC
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Introduction
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To the Editor:
The report from the Stroke Prevention: Assessment of Risk in a
Community (SPARC) study1 stating that atrial septal
aneurysm (ASA) is associated with an increased risk of stroke
is important for 2 reasons. (1) It definitively establishes the
prevalence of ASA in the general population at 2.2%. The true
prevalence of ASA was underestimated before the routine use of
echocardiography, especially
transesophageal
echocardiography.2 (2) It supports the
previous conjecture that paradoxical embolism is the predominant
mechanism of cardioembolism in ASA.3
Although 2 previous multicenter studies4 5 suggested
paradoxical embolism as a possibility among several other mechanisms,
including thrombus formation in the ASA, associated mitral valve
prolapse, associated mitral stenosis, and
supraventricular tachyarrhythmias, this
study was the first to prove conclusively that paradoxical embolism is
the principal mechanism for stroke in patients with ASA. This has
obvious and important therapeutic implications.
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References
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Agmon Y, Khandheria BK, Meissner I, et
al. Frequency of atrial septal aneurysms in
patients with cerebral ischemic events. Circulation. 1999;99:1942–1944.[Abstract/Free Full Text]
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Pearson AC, Labovitz AJ, Tatineni S, et al.
Superiority of transesophageal
echocardiography in detecting cardiac source of
embolism in patients with cerebral ischemia of uncertain
etiology. J Am Coll Cardiol. 1991;17:66–72.[Abstract]
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Cheng TO. Atrial septal aneurysm as a
"newly discovered" cause of stroke in patients with mitral valve
prolapse. Am J Cardiol. 1991;67:327–328.
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Mügge A, Daniel WG, Angermann C, et al. Atrial
septal aneurysm in adult patients: a multicenter study using
transthoracic and transesophageal
echocardiography. Circulation. 1995;91:2785–2792.[Abstract/Free Full Text]
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Marazanof M, Roudaut R, Cohen A, et al. Atrial septal
aneurysm: morphologic characteristics in a large population:
pathological associations: a French multicenter study on 259 patients
investigated by transesophageal
echocardiography. Int J Cardiol. 1995;52:59–65.[Medline]
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Response
Yoram Agmon, MD;
Bijoy K. Khandheria, MD;
Irene Meissner, MD;
Federico Gentile, MD;
Jack P. Whisnant, MD;
JoRean D. Sicks, MS;
W. Michael O’Fallon, PhD;
Jody L. Covalt, RN;
David O. Wiebers, MD;
James B. Seward, MD
Mayo Clinic,
Rochester, Minn
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Introduction
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We appreciate Dr Cheng’s interest in the Stroke Prevention:
Assessment
of Risk in a Community (SPARC) study and the recent
application of its
data in establishing the role of atrial septal
aneurysm (ASA)
as a source of cardioembolism.
R1 A major
contribution
of the SPARC study is the definition of the prevalence of
various
cardiac pathologies (eg, ASA) in a large
representative sample
of the population, as determined
by transesophageal echocardiography
(TEE).
The frequency of ASA observed in the SPARC population (2.2%)
was
similar to the frequency found in a large autopsy
study
R2 but
lower than that in previously reported TEE
studies.
R3 These
differences are related to the nature of
the SPARC population
(a large, random sample of the Olmsted County
population), as
well as to the rigorous definition of ASA
R4
and the blinded
review of the echocardiographic studies
by multiple observers
in our study.
Previous studies assessing the role of ASA as a cardiac source of
embolism have compared the frequency of ASA in patients undergoing TEE
after embolic events to its frequency in patients undergoing TEE for
other clinical indications (serving as controls).R5 These
control groups were highly prone to selection bias because of study
design. By contrast, the SPARC study uniquely enabled us to select an
appropriate control population, matched by age and sex to the group of
patients undergoing TEE after a cerebral ischemic event.
Comparison of the 2 study groups confirmed the association between ASA
and cerebral ischemic events. ASA was strongly associated with
right-to-left interatrial shunting. An interatrial shunt was the only
source of embolism in the majority of patients, suggesting that
paradoxical embolism is the major mechanism of ASA-related embolic
events. Additional studies are necessary to determine the optimal
treatment strategies (secondary prevention and, possibly, primary
prevention) for patients with ASA.
In summary, the SPARC study is the first study establishing the
prevalence of various cardiac sources of embolism in a large
population-based cohort. Data from SPARC should serve as the reference
to which patient populations are compared, as was done in our study on
ASA.
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References
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Agmon Y, Khandheria BK, Meissner I, et
al. Frequency of atrial septal aneurysms in
patients with cerebral ischemic events. Circulation. 1999;99:1942–1944.
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Silver MD, Dorsey JS. Aneurysms of the septum
primum in adults. Arch Pathol Lab Med. 1978;102:62–65.[Medline]
[Order article via Infotrieve]
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Jones EF, Calafiore P, McNeil JJ, et al. Atrial
fibrillation with left atrial spontaneous contrast detected by
transesophageal echocardiography is
a potent risk factor for stroke. Am J Cardiol. 1996;78:425–429.[Medline]
[Order article via Infotrieve]
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Hanley PC, Tajik AJ, Hynes JK, et al. Diagnosis and
classification of atrial septal aneurysm by two-dimensional
echocardiography: report of 80 consecutive cases.
J Am Coll Cardiol. 1985;6:1370–1382.[Abstract]
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Pearson AC, Nagelhout D, Castello R, et al. Atrial
septal aneurysm and stroke: a transesophageal
echocardiographic study. J Am Coll
Cardiol. 1991;18:1223–1229.[Abstract]
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Introduction
References