Kumar P, 69, had to skip his
Monday night poker game because a transient ischemic attack
(TIA) landed him in the hospital. He missed the next game
for a more serious reason — a stroke. Most guidelines
for dealing with TIAs stress the danger of stroke facing
the patient in the immediate aftermath, particularly the
first two days. But a study appearing in the March 8 issue
of Neurology suggests that these recommendations
underestimate the probability of a stroke following hard
on the heels of a TIA, and that the coast isn't clear
even up to a week later.
START
EARLY
Study author Dr Peter Rothwell of Oxford's Radcliffe
Infirmary said, "We have known for some time that TIAs
are often a precursor to a major stroke. What we haven't
been able to determine is how urgently patients must
be assessed following a TIA in order to receive the
most effective preventive treatment. This study indicates
that the timing of a TIA is critical, and the most effective
treatments should be initiated within hours of a TIA
in order to prevent a major attack."
The data in the Neurology
paper is drawn from four databases — the Oxford
Vascular Study, the Oxfordshire Community Stroke Project,
the UK-TIA Aspirin Trial and the European Carotid Surgery
Trial. Together, these studies included 2,416 subjects
who had suffered an ischemic stroke. In 549 patients,
TIAs were experienced prior to the stroke. In most cases,
the stroke occurred within seven days of the TIA with
17% occurring exactly a week later to the day and 9%
of strokes falling one day shy of a full week after
the TIA. The vast majority of strokes (43%) hit at some
point in the week after a TIA.
Several earlier studies have looked
at the risk of stroke following a TIA. Many North American
guidelines echo research published in 2000 in the Journal
of the American Medical Association, which suggested
that TIA patients run a 10% risk of stroke in the three
months following their attack. A more recent Canadian
investigation followed patients discharged from Ontario
stroke centres following TIAs. The research, published
in March 2004 in the Canadian Medical Association
Journal (CMAJ), found there was a 5% risk of stroke
in the three months following a TIA. The risk was slightly
higher after a first-ever TIA, and considerably higher
when the TIA brought on temporary motor or speech deficits.
TREATMENT
NEGLECTED
The converse figures reported in the Neurology
article are at least as frightening. Its retrospective
analysis found that no fewer than 23% of stroke victims
had suffered a previous TIA, and nearly half of these
TIAs occurred less than a week before the stroke. Whether
the true risk of stroke following TIA is 5% or 10%,
it seems clear that these patients are being under treated.
According to the CMAJ article,
only 31% of TIA patients received diagnostic imaging
before discharge. On average, 76% were discharged direct
from the emergency department. CT scan, MRI, cerebral
angiography and echocardiography were all used far less
than in stroke patients. Fewer than half of the TIA
patients received carotid Doppler ultrasonography within
30 days. Only one in 50 underwent carotid endarterectomy
within 90 days of their TIA.
Behind these unsatisfactory figures
lurks the even graver problem of the TIA patients who
never come to emergency, failing to recognize the seriousness
of their symptoms. New guidelines will have to address
the issue of patient education, as well as ensuring
that the guardians of expensive, in-demand diagnostic
equipment understand the urgent needs of this population.
The American Heart Asso-ciation
and its corollary, the American Stroke Association,
are already "completely revising" their TIA guidelines
and say the Neurology research will be incorporated.
Dr Rothwell has no doubt about what he wants to see
in the new approach: "Physicians should arrange specialist
assessment within 24 hours," he said.
Neurology Mar 8, 2005;64(5):817-20
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