CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 9, October 2012
526
AFRICA
experience almost twice as many strokes
as the stroke-naïve patients, the higher
dose of dabigatran loses its superiority
in stroke prevention to warfarin but is
still better than warfarin with regard to
reducing intracranial bleeds. This is in
concordance with the overall results of the
RE-LY trial.’
‘
Similarly, if the data from the
ARISTOTLE trial with apixaban is
analysed with regard to these patients,
the stroke rate was three times higher
than in those without a prior stroke.
Apixaban for these patients was shown
to be non-inferior to warfarin with fewer
haemorrhagic strokes and intracranial
bleeding events. Again concordance is
seen with regard to the overall results of
ARISTOTLE.’
‘
ROCKET-AF included 55% of
patients with prior stroke or TIA and
most patients were at risks above 2; only
13%
had a CHADS score of 2 and few
had a score of 1. Prof Hacke noted that the
patients with a prior stroke in ROCKET
were at even higher risk of stroke
(
CHADS score > 4) than the already high
risk levels within the ROCKET patient
cohort who had to have had a stroke,
TIA or systemic embolism or at least
two risk factors for inclusion in the trial.’
In these very vulnerable patients, there
were once again twice as many strokes as
in stroke-naïve patients, and rivaroxaban
treatment reduced the number of strokes,
with a clear trend towards lower rates of
intracranial and fatal bleeding’, he noted.
Practical advice on use of these
novel agents
The importance of counselling patients
when prescribing these new agents was
stressed by Prof Jafna Cox, Canada, who
noted that patients should be instructed
to not stop the drug without prior
consultation with their physician. Also
they need to be told how to manage
a missed dose of dabigatran using the
six-hour rule, and with rivaroxaban to just
take the drug even if later on the same
day. Not doubling the dose is an essential
warning for all of these agents.
‘
Inevitably, as we treat these patients,
we encounter patients with recent ACS
and they require on-going surveillance. I
avoid dabigatran in this situation, rather
choosing rivaroxaban but nonetheless
keeping a watchful, concerned eye over
developments.’
Withdrawal of these agents may
not always be necessary, particularly
when patients are undergoing low-risk
procedures. If there is bleeding on an
anticoagulant, tests such as the aPTT
for dabigatran and PT for rivaroxaban
are useful, as higher values indicate the
patient is still taking the drug. Action can
be initiated as for any bleeding event.
Expert comments
Dr Mike Bennett, Wilgers
Hospital, comments on the
developments related to novel
anticoagulant use in AF
Atrial fibrillation patients are poorly
treated. Physicians are afraid of warfarin
side effects and patients on warfarin
are often poorly controlled. They face
limitations with regard to diet and lifestyle,
with the required regular monitoring
intruding on their peace of mind. The new
oral agents are simple to use and as safe
as warfarin. It comes as no surprise to me
that the new ESC guidelines recommend
their use above warfarin for most patients.
It is absolutely clear that aspirin has
no place in stroke prevention in AF,
yet it is still commonly prescribed in
South Africa. Other absolutes for me in
stroke prevention in AF are that patients
older than 75 years and those of any
age who have had a stroke require oral
anticoagulation. With regard to stroke
patients, the absence of any remaining
symptoms of the incident does not
mean that the patient does not require
anticoagulation; the risk of a second
stroke remains.
The elderly are at particularly high
risk for a stroke and warfarin presents
particular challenges, so it is often not
prescribed. The older patient is usually
on multiple other medications, may have
cognitive problems and if living in a
retirement or old-age home is dependent
on others to give the medication. They
are dependent on their carers to get them
to clinics or doctors’ rooms where the
INR checks are done and their time in
therapeutic range (TTR) is frequently less
than ideal.
With regard to rivaroxaban, it is
attractive as a once-daily, fixed dose, it
requires no monitoring, is as safe and as
effective as warfarin, while also reducing
the risk of intracranial bleeds. It has no
food or drug interactions and allows the
patient to live without continually being
concerned about its use. Affordability is
an issue but this needs to be evaluated
against the significant healthcare costs of
warfarin.
J Aalbers
1.
Mega JL, Braunwald E Wiviott SD,
et al.
Rivaroxiban in pateints with a recent acute
coronary syndrome.
N
Engl J Med
2012;
366
(1): 9–19.
