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American College of Cardiology Extended Learning
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Aspirin Is No ‘Soft Option’ for Stroke Prevention in AF
A
trial fibrillation is a major cause of stroke
and thromboembolism, resulting in substantial morbidity and mortality. At the
end of 2015, the European Heart Rhythm Society
published a consensus document, “A Roadmap
to Improve the Quality of Atrial Fibrillation (AF)
Management.”1 The paper’s discussion on aspirin is
reproduced here in its entirety: Aspirin is not effective in preventing strokes in AF.
Well, the topic did come up a second time in
this 14-page report. Aspirin was addressed in
general in a table discussing indivi dual risk assessment, which recommended assessing bleeding
risk and minimizing bleeding risk factors in all
patients, including, “Discontinue treatment with
non-essential antiplatelet(s)/NSAIDs (nonsteroidal
anti-inflammatory drugs).”
By that measure, a paper by Gregory Y. H.
Lip, MD, professor of cardiovascular medicine,
University of Birmingham, United Kingdom, on
“The Role of Aspirin for Stroke Prevention in
Atrial Fibrillation” must be one of the shortest papers published.2 Not really: knowing that aspirin
is still used for this purpose, Dr. Lip did his best
to explain in detail just why
aspirin is a really poor choice
for stroke prevention in
patients with AF. He wrote:
“For the majority of patients
with AF, aspirin has a limited
role in stroke prevention,
To listen to an
being an inferior strategy and
interview with S.
not necessarily safer than
Ben Freedman,
the anticoagulant warfarin,
MBBS, on stroke
prevention in AF,
especially in the elderly.”
scan the code.
Compared with warfarin, for
The interview was
example, aspirin has only a
conducted by
Bernard J. Gersh,
marginal effect on reducing
ChB, DPhil, MB.
stroke but carries a similar
bleeding risk.
Having said that, Dr. Lip
added, “Aspirin use should
continue in the early stages
following presentation of a
patient with AF and acute
coronary syndrome, and
after stenting, in combination with oral anticoagulant drugs and clopidogrel, as appropriate.” (For
more on the topic of aspirin in patients with AF
and one or more drug-eluting stents, please see
the article that follows.) However, Dr. Lip noted
that aspirin combined with clopidogrel shows
only modest benefit in stroke prevention compared with aspirin monotherapy in patients with
AF who refuse oral anticoagulant drugs (including warfarin).
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CardioSource WorldNews
BLAME MARKETING
Recently, Dr. Lip coauthored a paper with S. Ben
Freedman, MBBS, professor of cardiology, University of Sydney, Concord Hospital, Australia.3 They
noted that people have been conditioned over many
years to accept aspirin as an effective, safe, and
inexpensive remedy for MI and for primary and
secondary prevention of cardiovascular events.
Indeed, the marketing of aspirin for this very
purpose has been so wildly successful that a recent advertising campaign focused on the fact that
aspirin can still be used as a pain reliever. (When
offered an aspirin for pain, a man responds, “I’m
not having a heart attack.”)
The current ACC/AHA Guideline for the
Management of Patients With Atrial Fibrillation
states, that for patients with nonvalvular AF and
a CHA2DS2-VASc score of 1, “No antithrombotic
therapy or treatment with an oral anticoagulant or
aspirin may be considered.”4 However, in previous
guidelines, aspirin was recommended as thromboprophylaxis for those not considered at high risk
(e.g., CHADS2 score < 2).
Why the change? According to the writing
committee’s chair, Craig T. January, MD, PhD,
“Data showing that aspirin decreases stroke risk
are weak.”
However, the previous guidelines set a pattern
that remains today in a lot of practices. Overall,
a little more than one-third of AF patients on oral
anticoagulation (OAC) also receive ASA.5 While
aspirin is no longer recommended, Dr. Freedman
and colleagues note, “Unfortunately, the implied
benefit of guideline approbation probably led to
widespread use of aspirin as the ‘easy’ or ‘soft’
option in those at higher stroke risk with either
real or perceived contraindications to vitamin K
antagonist (VKA; e.g., warfarin).”
This could be the result of differences in
perception among physicians and patients regarding the risk of stroke versus bleeding and also the
misperception that aspirin is somewhat effective
in stroke prevention in this setting and has a lower
bleeding risk. Another possible contributory factor
may be an exaggerated estimate of VKA-associated
bleeding, feared by physicians who do not see the
strokes prevented but do see the bleeds.
Coupled with this is the issue that VKA therapy is
hard to manage, and appears to be universally disliked
by physicians, patients, the media, and industry.
DISSERVICE TO PATIENTS
Dr. Freedman argues that the consequences of the
underutilization of OAC are documented in the
neurology literature reviewing incident strokes.
The Adelaide Stroke Study reported in 2013 that
AF accounted for 36% of all ischemic strokes, of
which 85% were inadequately anticoagulated despite the fact that all of them had a CHADS2 score
≥ 2.6 Specifically, only 27% of those with known
AF prior to stroke were taking warfarin, while
most of the remaining two-thirds were on aspirin.
In previous studies of AF-related strokes in
which the patient was known to have AF prior to
stroke, aspirin was being taken by half of those
not on warfarin. This suggests that, rather than
improving over time, the situation may have actually gotten worse.
And forget the idea that aspirin is some sort of
‘soft’ option: in BAFTA (Birmingham Atrial Fibrillation Treatment of the Aged Study), aspirin was
associated with a similar risk of major bleeding and
intracranial hemorrhage as warfarin.7 As Dr. Freedman puts it, “If you are trading the same amount of
bleeding for less efficacy, that’s a bad tradeoff.”
Bottom line: Aspirin is neither effective nor
safe for thromboprophylaxis for stroke. ■
REFERENCES:
1. Kirchhof P, Breithardt G, Bax J, et al. Europace. 2015 Oct
18. [Epub ahead of print]
2. Lip GY. Nat Rev Cardiol. 2011;8:602-6.
3. Ben Freedman S, Gersh BJ, Lip GY. Eur Heart J.
2015;36:653-6.
4. January CT, Wann LS, Alpert JS, et al. J Am Coll Cardiol.
2014;64:e1-76.
5. Steinberg BA, Kim S, Piccini JP, et al. Circulation.
2013;128:721-8.
6. Leyden JM, Kleinig TJ, Newbury J, et al. Stroke.
2013;44:1226-31.
7. Mant J, Hobbs FD, Fletcher K, et al. Lancet. 2007;370:493503.
Take-aways
• Despite the fact that it is still commonly used for
this purpose, aspirin is not effective in preventing
strokes in AF.
• The current ACC/AHA guidelines on the
management of patients with AF strongly
diminished the role of aspirin compared with
earlier gu idelines, but many clinicians continue to
consider aspirin a ‘soft’ option for some patients.
• Some of this may be due to clinical habits left over
from previous iterations of the guidelines; another
contributory factor may be an exaggerated
estimate of warfarin-associated bleeding,
feared by physicians who do not see the strokes
prevented by optimal anticoagulation, but do see
the bleeds.
• Aspirin is neither effective nor safe for
thromboprophylaxis for stroke.
February 2016