The International Stroke Trial (IST) is a multicentre controlled study
which aims at testing various antithrombotic treatments in patients with
an acute ischaemic stroke within 48 hours. Patients are randomised to:
ASA 300 mg/die, Subcutaneous Heparin 5000 U X 2, Subcutaneous Heparin 12500
U X 2, ASA + Heparin 5000 X 2, ASA + Heparin 12500 X 2, or no antithrombotic
drug. Results on 14 days outcome are available on 19331 patients, from
467 Hospitals in 36 Countries. (77 Italian Centres, both Medical and Neurological
Divisions, , with more than 3000 patients included). Since in the first
analysis no significant interaction appeared between ASA and Heparin, the
original factorial design is now used in summarising the data.
Heparin: no significant effect on 14 days death rate (9% vs 9.3%),
nor on early recurrent strokes (3.8% vs 3.9%); however, when looking at
the different etiology of the recurrent strokes, it appears that the number
of ischaemic episodes is actually reduced by heparin, but there is a relevant
increase of cerebral haemorrhages, which offsets any possible benefit.
Furthermore, major extracerebral haemorrhages (that is, those requiring
transfusion) are increased as well; pulmonary embolism is slightly reduced
(0.8 vs 0.5%). To summarise, Heparin saves 9 ischaemic strokes per 1000
treated patients, but causes 8 intracranial and 9 major extracranial haemorrhages:
treating 60 patients with heparin can cause a severe haemorrhage. No clear
advantage appeared in any of the studied subgroups (patients with Atrial
Fibrillation, etc.), and therefore, while waiting for the final results,
we cannot recommend the routine use of heparin in acute stroke.
Aspirin: no significant effect on 14 days death rate (9% vs 9.3%),
but a significant reduction of early recurrences (2.6% vs 3.5%), not offset
by the small increase in intracranial haemorrhages (0.8% vs 0.7%); major
extracerebral haemorrhages are increased by 0.5%, and pulmonary embolism
is slightly reduced (0.8% vs 0.6%). To summarise, ASA saves 10 deaths or
early recurrences per 1000 treated patients, without major significant
risks. We conclude that patients with acute ischaemic stroke should be
immediately treated with ASA, if no important controindication exists.
Final results, with 6 months follow up data, will be available at the end
of May 1997.