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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 31, No 3, May/June 2020
AFRICA
155
blockers (
β
-blockers), non-dihydropyridine calcium channel
blockers (ND-CCBs), digitalis and amiodarone (Table 2).
The choice of these drugs should be based on individual
characteristics and a patient’s preferences.
β
-blockers are the
preferred first-line agents for rate control during AF owing
to the efficacy (lower heart rates) as well as potential survival
advantage.
18
The most commonly used
β
-blockers are metoprolol,
bisoprolol and atenolol. Contra-indications should be considered
before we use
β
-blockers; briefly, acute pulmonary oedema,
heart failure, asthma, severe atrioventricular block and severely
depressed patients cannot choose
β
-blockers.
Commonly used ND-CCBs include diltiazem and verapamil,
which are recommended for AF combined with chronic
obstructive pulmonary disease or asthma. Digitalis can slow
ventricular rate through increasing vagus nerve tension, so it
is a reasonable alternative for those patients in whom other
treatments are ineffective or contra-indicated, especially in heart
failure and hypotension. Amiodarone can reduce ventricular
rate due to its short-term effect in blocking calcium channels
and the sympathetic nervous system, but it is not used for long-
term ventricular rate control. Amiodarone can be useful for rate
control when other drugs are ineffective or contra-indicated and
for acute symptoms.
The latest ESC guidelines
21
use LVEF = 40% as the dividing
line. Patients with LVEF
≥
40% can use
β
-blockers, ND-CCBs
and digitalis to control ventricular rate (Class I, level of evidence
B), while
β
-blockers should start from a low dose for patients
with LVEF
<
40%, and ND-CCBs should be avoided (Class I,
level of evidence B).
Prevention of stroke
Patients withAF are five times more likely to have a stroke,
22
which
has long attracted the attention of clinicians. Besides, cognitive
impairment, silent cerebral infarcts, memory impairment,
hippocampal atrophy, Alzheimer’s disease and other forms of
dementia have been demonstrated at a higher prevalence in AF
compared with non-AF.
23
Anticoagulant therapy is highly recommended in preventing
strokes for AF patients. CHA
2
DS
2
-VASc (Table 3) and
HAS-BLED (Table 4) scoring systems are recommended to
be used before anticoagulant therapy. There is strong evidence
that patients with a CHA
2
DS
2
-VASc risk score of two or
more in men, and three or more in women, benefit from oral
anticoagulants (Class I, level of evidence A). Oral anticoagulants
should be considered for men with a CHA
2
DS
2
-VASc score of
one and women with a score of two, balancing the expected
stroke reduction, bleeding risk, and patient preference (Class IIa,
level of evidence B). No antiplatelet or anticoagulant therapy is
recommended for men with a CHA
2
DS
2
-VASc score of zero and
women with a score of one (Class III, level of evidence B).
21
Low bleeding risk refers to a HAS-BLED score of two or less,
while a score of three or more puts the patient at high bleeding
risk. HAS-BLED score is a tool for clinicians to objectively
assess the risk of bleeding in AF patients, aiming to treat
reversible risk factors, especially for high-risk bleeding patients.
Choices of anticoagulant drugs are new oral anticoagulants
(NOACs, including the direct thrombin inhibitor dabigatran and
the factor Xa inhibitors apixaban, edoxaban and rivaroxaban)
and oral anticoagulants (OACs, such as warfarin).
According to the latest ESC guidelines,
21
NOACs are the
preferred therapy unless contra-indications exist in patients,
and OACs are secondary choices (Class I, level of evidence A).
A meta-analysis
24
of NOACs versus warfarin included 42 411
participants receiving NOACs and 29 272 participants receiving
warfarin. It demonstrated that NOACs significantly reduced
stroke or systemic embolic events by 19% compared with warfarin
(RR 0.81, 95% CI 0.73–0.91;
p
<
0.0001). NOACs also reduced
all-cause mortality by 10% (0.90, 0.85–0.95; p
<
0.0001), while
gastrointestinal bleeding events were more frequent (1.25, 1.01–
1.55;
p
= 0.04). NOACs had a favourable risk–benefit profile,
with significant reductions in stroke, intracranial haemorrhage
and mortality rates, and with similar major bleeding events to
warfarin. The efficacy and safety of NOACs over warfarin seem
to be even greater in East Asians compared with non-Asians.
25
But in the latest ESC guidelines,
21
warfarin is recommended for
stroke prevention in AF patients with moderate-to-severe mitral
stenosis or mechanical heart valves (Class I, level of evidence B).
Combinations of OACs and platelet inhibitors increase
bleeding risk and should be avoided in AF patients without
another indication for platelet inhibition (Class III, level
of evidence B). Aspirin is neither effective nor safe as
thromboprophylaxis for AF patients, even possibly increasing
stroke risk in elderly patients.
26,27
During anticoagulant therapy,
monitoring the coagulation function is necessary to ensure the
efficacy and safety of anticoagulants.
Direct-current cardioversion (DCC)
DCC is an effective therapy for AF patients or AF with rapid
ventricular response to restore sinus rhythm. If unsuccessful,
repeat DCC attempts should be made after applying pressure
over the electrodes or adjusting the location of the electrodes or
combining with anti-arrhythmic drugs.
28
DCC is recommended
for AFpatients who do not respond to pharmacological therapies,
combined with heart failure or haemodynamic instability.
21,28
A study of the effect of early DCC on the recurrence of AF
Table 3. CHA
2
DS
2
-VASc scoring system
Risk factor
Score
Chronic heart failure
1
Hypertension
1
Age
≥
75 years
2
Diabetes
1
Previous stroke/transient ischaemic attack
2
Vascular disease
1
Age 65–74 years
1
Gender category (female)
1
Table 4. HAS-BLED scoring system
Risk factor
Score
Hypertension
1
Abnormal renal function
1
Abnormal liver function
1
Stroke
1
Bleeding history or predisposition
1
Labile INR
1
Elderly (> 65 years)
1
Drugs concomitantly
1
Alcohol concomitantly
1