CARDIOVASCULAR JOURNAL OF AFRICA • Vol 22, No 2, March/April 2011
106
AFRICA
Stroke risk reduction: focus of the new ESC guidelines
CHADS
2
risk scoring is an easy off-top-
of-the-head method to measure stroke
risk in atrial fibrillation (AF) patients, but
misses true predictive value and should
be replaced by CHADS plus vascular
risk (CHA
2
DS
2
-VASC). This expansion
to the CHADS risk score is advocated
in the new expert ESC guidelines for the
management of atrial fibrillation.
1
Atrial fibrillation is the commonest
cardiac arrhythmia, occurring in 1–2%
of the general population, with its preva-
lence set to double as populations age.
This arrhythmia is responsible for one in
five strokes worldwide and is of particular
concern because AF-associated strokes
are often fatal, with surviving stroke
patients left more disabled by their stroke,
and also facing an increased likelihood of
suffering a further stroke.
This vulnerability results in increased
costs of care for AF-related stroke, some
50% higher than non-AF-related stroke.
Atrial flutter carries a similar risk of
stroke and in these patients stroke-risk
prediction is very important.
The CHADS
2
risk score was developed
in the early 2000s and was initiated by the
AF investigators and Stroke Prevention in
Atrial Fibrillation (SPAF) investigators.
2
In this point system, stroke/TIA is award-
ed two points, and one point each for year
above 75 years, hypertension, diabetes or
recent cardiac failure. The adjusted stroke
rate was determined from data based on
a cohort of hospitalised AF patients. This
score is now well established and forms
an ideal base for the more predictive
CHA
2
DS
2
-VASC score (Table 1).
Using the new CHA
2
DS
2
-VASC score,
effective vitamin K antagonist (VKA)
anti-coagulation treatment within INR
targets of 2 to 3 is recommended for
patients with AF with a score of 1 and
higher, provided there are no contra-
indications and with appreciation of the
patient’s values and perceptions.
The guidelines note that there is no
place for aspirin therapy in AF-related
stroke prevention, except perhaps in
younger women under the age of 65 years
with no other risk factors than AF. This
view was mainly based on the magnitude
of stroke reduction from aspirin versus
placebo, which showed a non-significant
19% benefit of aspirin over placebo in
AF-related stroke.
3
In the ACTIVE-W trial,
4
warfarin was
shown to be superior to the combination
of clopidogrel plus aspirin, with no differ-
ence in bleeding events between treat-
ment arms. In fact, the ESC guidelines
suggest that, based on this trial, which
mainly recruited patients who physicians
regarded as being unsuitable for VKA
therapy, the combination of aspirin and
clopidogrel could perhaps be best seen as
an interim measure where VKA is unsuit-
able, rather than an alternative to VKA in
patients at high bleeding risk.
Direct comparisons have also been
made between VKA and aspirin in stroke
prevention, showing significant superior-
ity of warfarin to aspirin, with a relative
risk reduction of 39%; and no differ-
ence in the risk of major haemorrhage
between warfarin and aspirin.
5
While
the ESC guidelines refer only briefly to
new investigational agents, they note the
importance of the RE-LY study on the
oral, direct thrombin inhibitor, dabigatran
etexilate.
1
In the RE-LY (Randomised Evaluation
of Long-term anticoagulant therapY with
dabigatran etexilate) study, dabigatran
110 mg b.i.d. was shown to be non-infe-
rior to VKA for the prevention of stroke
and systemic embolism, with lower rates
of major bleeding. Dabigatran 150 mg
b.i.d. however was associated with lower
rates of stroke and systemic embolism
with similar rates of major haemorrhage,
compared with VKA.
6
With the recent FDA approval of dabi-
gatran for stroke reduction inAF, this anti-
coagulant has a significant role to play in
the arena of stroke prevention in AF.
J Aalbers, Special Assignments Editor
1. Camm AJ, Kirchoff P, Lip GYH, Schotten U,
Savelieva I, Ernst S,
et al
. Guidelines for the
management of atrial fibrillation. The task
force for the management of the European
Heart Rhythm Association (EHRA).
Eur
Heart J
doi:10.1093/eurheartj/ehq278.
2. Gage BF, Waterman AD, Shannon W,
Boechler M, Rich MW, Radford MJ.
Validation of clinical classification schemes
for predicting stroke: results from the
National Registry of Atrial Fibrillation.
J Am
Med Assoc
2001;
285
: 2864–2870.
3. Hart RG, Pearce LA, Aguilar MI. Meta-
analysis: antithrombotic therapy to prevent
stroke in patients who have nonvalvular
atrial fibrillation.
Ann Intern Med
2007;
146
:
857–867.
4. Connolly S, Pogue J, Hart R, Pfeffer M,
et
al
. Clopidogrel plus aspirin versus oral anti-
coagulation for atrial fibrillation in the Atrial
fibrillation Clopidogrel Trial with Irbesartan
for prevention of Vascular Events (ACTIVE
W): a randomised controlled trial.
Lancet
2006;
367
: 1903–1912.
5. Mant J, Hobbs FD, Fletcher K, Roalfe A,
Fitzmaurice D, Lip GY, Murray E. Warfarin
versus aspirin for stroke prevention in
an elderly community population with
atrial fibrillation (the Birmingham Atrial
Fibrillation Treatment of the Aged Study,
BAFTA): a randomised controlled trial.
Lancet
2007;
370
: 493–503.
6. Connolly SJ, Ezekowitz MD, Yusuf S
Eikelboom J,
et al
. Dabigatran versus warfa-
rin in patients with atrial fibrillation.
N Engl
J Med
2009;
361
: 1139–1151.
TABLE. 1 CHA
2
DS
2
-VASC SCOREAND
STROKE RATE
1
(a) Risk factors for stroke and thrombo-
embolism in non-valvular AF
‘Major’risk factors
‘Clinically relevant non-
major’risk factors
Previous stroke, TIA, or
systemic embolism
Age
≥
75 years
Heart failure or moder-
ate to severe LV systolic
dysfunction (e.g. LV EF
≤
40%)
Hypertension, diabetes
mellitus female gender,
age 65–70 years vascu-
lar disease
(b) Risk factor-based approach expressed as a
points-based scoring system, with the acro-
nym CHA
2
DS
2
-VASc (Note: maximum score
is 9 since age may contribute 0, 1 or 2 points)
Risk factor
Score
Congestive heart failure/LV dysfunction
1
Hypertension
1
Age
≥
75 years
2
Diabetes mellitus
1
Stroke/TIA/thrombo-embolism
2
Vascular disease
1
Age 65–74 years
1
Gender category (i.e. female)
1
Maximum score
9
(c) Adjusted stroke rate according to
CHA
2
DS
2
-VASc score
CHA
2
DS
2
-
VASc score
Patients
(
n
=
7 329)
Adjusted stroke
rate (%/year)
0
1
0
1
422
1.3
2
1230
2.2
3
1730
3.2
4
1718
4.0
5
1159
6.7
6
679
9.8
7
294
9.6
8
82
6.7
9
14
15.2
