CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 6, July 2013
AFRICA
243
Drug Trends in Cardiology
Anticoagulation: ‘Putting new evidence into clinical practice’
A CPD evening recently hosted in Cape
Town examined the clinical implementa-
tion and implications of recent evidence
on the novel oral anticoagulants (NOACs).
Dr Hans-Christian Mochmann (cardio-
logist) and Dr Jan Beyer-Westendorf
(vascular physician) discussed NOAC
therapeutic outcomes in both clinical
trials and daily practice, sharing their
experience in the use of these agents.
Thedemographictransitiontoincreased
life expectancy is a global phenomenon,
accompanied by increased incidence of
stroke in the ageing population. Virchow’s
triad describes the elements essential to
thrombosis as blood stasis (secondary
to immobility, congestive heart failure
and vein compression), alteration in the
vein wall (secondary to prior thrombosis,
inflammation or infection, direct wall
trauma and varicose veins), and blood
hypercoagulability (a result of, among
others, antiphospholipid syndrome,
lower-limb surgery or trauma and
hyperhomocysteinaemia).
Of the two main types of stroke,
ischaemic stroke is the most common,
caused by a blood clot formed in a
blood vessel or elsewhere, which is then
transported in the blood (embolism).
Haemorrhagic stroke arises from rupture
of a blood vessel, which leads to bleeding
in the brain or on the brain surface.
Haemorrhagic stroke represents 15–20%
of all strokes.
Atrial fibrillation
Atrial fibrillation (AF) is the most
common form of sustained abnormality
of heart rhythm and represents a major
risk factor for stroke due to thrombus
formation in the left atrial appendage. The
risk of AF increases with age. The risks of
diabetes and hypertension also increase
with age and are independent predictors
of AF. Patients with stroke due to AF
have a greater mortality risk and a higher
severity of stroke compared to non-AF
stroke patients.
Dr Mochmann addressed the question
of how to prevent stroke in AF patients
today. In 2012, the European Society of
Cardiology adopted the CHA
2
DS
2
-VASc
score assessment (Table 1), developed
particularly to improve stroke predictive
value in low-risk patients. A maximum
score of 9 indicates a 15.2% stroke
risk per year. Oral anticoagulation is
recommended in individuals with two or
more risk factors.
Warfarin has been successfully used
over many decades, demonstrating a
62% risk reduction in stroke across trials.
However, INR therapeutic range is hard
to control on a daily basis. Only 50% of
all measurements are found to be within
the target INR range of 2.0–3.0, which
represents a fine balance between the
risk of stroke and risk of bleeds. Other
obstacles presenting with warfarin use
are the high incidence of side effects, low
patient adherence (approximately 50%
loss of compliance at three years) and
multiple drug interactions.
Novel antithrombotic therapies include
the NOAC, dabigatran, a direct thrombin
inhibitor, and the factor Xa inhibitors,
rivaroxaban and apixaban. Dr Mochmann
paid particular attention to the use of
rivaroxaban in non-valvularAF, presenting
the ROCKET-AF trial outcomes on the
use of rivaroxaban compared to warfarin
in elderly patients with high CHADS
2
scores, many with previous stroke. These
patients presented with both high risk of
another stroke and a high risk for bleeds.
Results indicated that rivaroxaban
was at least as effective as warfarin in
reduction of stroke/systemic embolus in
these fragile patients. Rivaroxaban and
Dr Hans-Christian Mochmann
Dr Mochmann is consultant of cardiology
at Charite Campus Benjamin Franklin,
Berlin, Germany. He focuses on coronary
interventions and is responsible for
pre-hospital emergency medicine
involving mobile ICUs and Berlin’s rescue
helicopter Christoph 31.
Dr Jan Beyer-Westendorf
Dr Beyer-Westendorf is head of the
Thrombosis Research Unit at the Centre
for Vascular Medicine and Department
of Medicine at the University Hospital
Carl Gustav Carus in Dresden, Germany.
He also serves as deputy head of the
Angiology Division at the same hospital.
TABLE 1. STROKE RISKASSESSMENT:
CHA
2
DS
2
-VASc SCORE
Risk factor
Points
C Congestive heart failure/left =
ventricular dysfunction
1
H Hypertension
1
A
2
Age
≥
75 years
2
D Diabetes mellitus
1
S
2
Stroke/transient ischaemic attack/
thromboembolism
2
V Vascular disease (prior myocardial
infarction, peripheral artery disease,
aortic plaque)
1
A Age 65–74 years
1
Sc Gender category (i.e. female)
1
