EDITORIAL
SA JOURNAL OF DIABETES & VASCULAR DISEASE
54
VOLUME 7 NUMBER 2 • JUNE 2010
Atrial fibrillation in Africa
GIDEON VISAGIE
A
trial fibrillation is a common disorder with serious
consequences. The estimated prevalence of this condition
is between 0.4 and 1% in western populations.
1
It
amounts to an annual expenditure of approximately US$ 7 billion
per year in the United States.
2
No specific figures are available for
South Africa, but in the Heart of Soweto study, it was reported
that 7% of patients referred for a new cardiac problem had atrial
fibrillation.
3
The physician faced with a patient with atrial fibrillation has
three points to consider in the management of this condition. The
first is stroke prevention and the role of anti-coagulation; secondly,
whether a rate- or rhythm-control strategy should be employed.
Finally, referral to a cardiologist for advanced management should
also be considered. In the last few years, exciting progress has been
made concerning all aspects of atrial fibrillation management.
One out of every six strokes occurs in a patient with non-valvular
atrial fibrillation.
4
The risk for stroke increases with an increased
CHADS2 score, varying from 1.9% per year for a CHADS2 score
of 0, to 18.2% per year for a CHADS2 of 6.
1
It is therefore
recommended that all patients with atrial fibrillation should be on
anti-thrombotic therapy.
1,4
The gold standard has been warfarin,
which has a significant (
>
50%) decrease in stroke rate compared
to placebo.
5
Alternatively, in patients with lower risk, aspirin or the
combination of aspirin and clopidogrel also reduces stroke risk.
6
A new era of anti-thrombotic agents has, however, dawned.
The first of these agents to be evaluated in atrial fibrillation was
the direct thrombin inhibitor, dabigatran. In the RELY study,
which was published last year, this agent was shown to be as
effective as warfarin in reducing stroke and embolism, with fewer
haemorrhagic complications. The same trial demonstrated that
with a slightly higher dose (150 mg), it was more effective than
warfarin in preventing stroke and embolism, with a similar risk of
haemorrhage.
7
The additional advantage of not having to follow a
patient’s INR makes this drug even more attractive.
The next group of agents in the process of evaluation for atrial
fibrillation is the oral factor Xa inhibitors. The two drugs in this
class include rivaroxaban and apixaban. The ROCKET-AF study
evaluating rivaroxaban was completed and results are pending.
Apixaban was compared to warfarin in the ARISTOTLE study. A
new inhibitor of vitamin K, epoxide reductase, code named ATI-
5923, is also in development.
8
The second factor in the management of a patient with atrial
fibrillation is whether a strategy of rate or rhythm control should
be adopted. This question has been addressed by multiple large
studies, including the AFFIRM, RACE, STAF, PIAF, HOT Café and,
most recently, the AF-CHF study.
4,9
These studies have shown that
rate control is at least equal to rhythm control.
Earlier this year, the RACE-II study was published, which
investigated target heart rate if a rate-control strategy is to be
followed. In the 2006 ACC/AHA/ESC guidelines, target heart rate
was suggested to be between 60 and 80 beats per minute (bpm)
at rest and between 90 and 115 bpm during exercise.
4
The RACE-II
study showed however that lenient control (resting heart rate of
less than 115 bpm) was as effective as the above goals, and that
this rate is more easily achieved.
10
There has also been development on the front of anti-arrhythmic
drugs for atrial fibrillation. Dronedarone is an amiodarone analogue
with a shorter half-life and less systemic side effects. It has a lower
efficacy than amiodarone and may not be used in patients with a
left ventricular ejection fraction of less than 35%.
11
In the ATHENA
trial, it was shown that dronedarone substantially decreased all-
cause mortality and hospital admissions in patients with atrial
fibrillation.
12
Vernakalant is an atrial selective drug that is currently
being compared to amiodarone in a phase 3 superiority trial (AVRO
trial) for the treatment of atrial fibrillation.
4
Catheter ablation techniques are becoming more important.
These techniques include ablation of the AV node, with subsequent
pacemaker implantation and pulmonary vein isolation. In recent
trials, it was shown that patients who previously did poorly with
anti-arrhythmic therapy, where catheter ablation was used as
second-line therapy, sinus rhythm could be achieved in up to 74%
of these subjects.
13
There is also some evidence suggesting that
radiofrequency catheter ablation improves the patient’s quality of life
and may reduce the need for anticoagulation.
14
A recently initiated
study, the CABANA (Catheter Ablation versus Antiarrhythmic Drug
Therapy for Atrial Fibrillation) trial, is a multi-centre trial aiming to
enrol 3 000 patients in order to ascertain whether catheter ablation
is more effective than anti-arrhythmic therapy.
15
Interventional cardiology is also providing alternatives to the use
of anticoagulation. It is known that the left atrial appendage is the
source of emboli in atrial fibrillation in more than 90% of cases.
16
Correspondence to: Gideon Visagie
Department of Internal Medicine, Faculty of Health Sciences, University of the
Free State, Bloemfontein
Tel: +27 (0)51 405-3154
e-mail:
S Afr J Diabetes Vasc Dis
2010;
7
: 54–55.
Gideon Visagie
