CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 3, April 2013
AFRICA
89
NIHSS scores at 30 and 90 days and death, myocardial infarction
or second stroke within 30 days. A good neurological outcome
was defined as MRS < 2 (i.e. either asymptomatic or no
significant disability) or a NIHSS score improvement
≥
10 points.
Recanalisation (TIMI 2–3) was achieved in 46% of treated
patients, with these patients having better neurological outcomes.
The risk of stroke, MI or death at 30 days was 40% and mortality
rates at 90 days were 43.5%. Increasing age and a higher
admission NIHSS score were associated with higher mortality
rates. Clinically significant procedural complications occurred
in 7.1% of patients and sICH in 7.8% of patients.
In the Multi MERCI trial, 160 patients were treated within
eight hours of stroke onset.
26
In this study, prior treatment with
IV r-tPA, mechanical clot disruption, IA thrombolysis and
other adjunctive therapies were allowed. IV r-tPA had been
administered to 29% of the participants without recanalisation
prior to the procedure. Recanalisation was achieved in 55%
of patients with the retriever alone and in up to 68% when
adjunctive therapies were used. At 90 days good neurological
outcomes (mRS
≤
2) were achieved in 36% of patients and
NIHSS scores improved > 10 points in 26% of patients.
Given that clot burden in the internal carotid artery terminus
and basilar artery can be substantially higher and therefore less
likely to be recanalised with thrombolytics, the data suggest that
the device provides an advantage over IA thrombolytic therapy
alone for all large-vessel occlusions.
26
Treatment with IV r-tPA
prior to MERCI device deployment did not increase the chance
of sICH. Overall mortality at 90 days was 34%. Although the
mortality rates were relatively high in both MERCI and Multi
MERCI trials this most likely represents the overall stroke
severity of the patients enrolled.
The penumbra system works proximally to disrupt and
aspirate the thrombus. It comprises a series of devices, primarily
an aspiration catheter, with a distal wire to keep the catheter
clear, and a grasping device designed to remove harder thrombus
if the aspiration device fails to recanalise the vessel.
A prospective multi-centre trial of the penumbra system
enrolled 125 patients presenting within two hours of stroke.
27
The primary endpoints were vessel revascularisation and device
safety. Recanalisation rates were 81.6% and serious adverse
rate was 3.2%. An NIHSS score showed improvement of >
4 points in 57.8% of patients and an mRS
≤
2 at 90 days in
25% of patients. Mortality rates at 30 and 90 days were 26 and
32.8%, respectively. More recent studies with the device reported
recanalisation rates of between 85 and 93%.
24
A review of all studies to date with neurothrombectomy
devices revealed widely varying rates of recanalisation (43–78%
with MERCI retriever and 83–100% with the penumbra system).
Rates of harm included symptomatic (0–10% with MERCI
and 0–11% with penumbra system) or asymptomatic (28–43
and 1–30%, respectively) intracranial haemorrhage. Vessel
perforation or dissection (0–7 and 0–5%, respectively) also
varied by device.
28
Predictors of poor outcome were age, history
of stroke, and higher baseline severity scores. Successful
recanalisation was the sole predictor of good outcomes.
28
Despite the FDA approving the MERCI device in 2004 and
the penumbra system in 2007 for use in acute ischaemic strokes,
their clinical efficacy is yet to be fully established in a controlled
outcomes trial.
24
The data as published are enticing and one is
already seeing an increase in the use of these devices. The main
problems remain patient selection, type and nature of stroke and
clinical outcome. The studies have focused on recanalisation as
the sole measure of outcome but, as in the IV r-TPA trials, it
should really be clinical outcome.
Endovascular angioplasty and stenting
Balloon angioplasty with or without stent placement, as is used
in patients with acute myocardial infarction, has been used to
recanalise cerebral arterial occlusions. Unlike cardiac arteries
which have the firm muscular support of the myocardium,
cerebral arteries are suspended in cerebrospinal fluid and
are hence more prone to dissections and tears. Furthermore,
the approach to cerebro-arterial occlusions is often tortuous,
making navigation much more difficult. Reperfusion rates of
approximately 80% with mortality of about 30% have been
reported.
24
However the AHA guidelines do not recommend this
form of treatment.
12
Stent-based thrombectomy
Self-expanding stents for cerebral use have advantages over
balloon angioplasty as they can be delivered to the target vessel
with reduced barotrauma, thereby decreasing the risk of rupturing
or dissecting the cerebral vessel.
29
Moreover, they adapt much
better to the shape and anatomy of the affected artery.
The solitaire AB stent is a self-expanding microstent. The
device is deployed at the level of occlusion and the clot is
enmeshed in the stent and then removed proximally. Studies have
shown successful revascularisation in patients presenting within
eight hours of AIS.
24
A recent study suggest that recanalisation
rates > 85% can be achieved with the Solitaire stent in anterior
large-vessel occlusions, thereby substantially increasing the
rate of good outcome for these patients with an otherwise poor
prognosis.
30
The above endovascular approaches for treatment of stroke are
viable but costly. They require a dedicated stroke interventionalist
with a support team of angiography technicians and nurses.
The equipment needed to carry out these procedures is also
expensive. Careful selection of patients is imperative in order
to achieve maximum benefit. In South Africa, interventionalists
are few, and hence this poses a greater difficulty in achieving the
ultimate goal of early reperfusion.
Multimodal reperfusion therapy
Faster and more complete recanalisation should translate into
better patient outcomes. To achieve this, the trend in acute
coronary syndromes has been to use multiple pharmacological
agents and, increasingly, percutaneous coronary intervention.
However, currently available data do not provide conclusive
evidence for either the safety or efficacy of combinations of
medications to improve cerebral perfusion. Data with regard to
the usefulness of mechanical devices to augment the effects of
pharmacological thrombolysis to treat AIS are also limited.
Prevention of recurrent stroke
Antiplatelets
Aspirin is widely used for the prevention of recurrent stroke in
patients with transient ischaemic attack (TIA) and ischaemic
