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18 May 2018.

After a heart attack about 20% of patients have a recurrent event within 12 months. Prevention is largely aimed at platelets, small circulating cell fragments involved in blood clotting, by treatment with low-dose aspirin and a platelet inhibitor. A new study has investigated whether those at higher risk of recurrence have a problem with the ability of plasma proteins to dissolve a clot after it has formed, opening up the possibility of an additional approach to prevention.

A large international trial compared 12 months treatment with a new platelet inhibitor with an old one as an addition to low-dose aspirin in 18,624 patients who had been admitted to hospital with a heart attack. A sub-study of that trial by researchers from Sheffield University led by Professor Robert Storey of the Department of Infection, Immunity and Cardiovascular Disease was published online in the European Heart Journal on 29 January 2018. They examined frozen plasma stored by Uppsala Clinical Research Centre from 4,354 patients in the international trial who had had blood samples taken as they were discharged from hospital.

A high-throughput automated system was used to measure the time it took the turbidity of plasma to fall by 50% after clotting, called the clot lysis time. In addition maximum clot turbidity was recorded and a number of biomarkers that increase during a heart attack were measured including troponin T, cystatin C, B-type natriuretic peptide (BNP) and C-reactive protein (CRP). There were strong associations between lysis times and the biomarkers.

Rates of heart attack and death from cardiovascular disease in the year after discharge from hospital were highest in those with the highest lysis times. This finding remained significant after adjustment for known clinical characteristics and for the association of lysis time with biomarkers. The quarter of patients with the highest lysis times had a 40% increased risk.

Professor Storey said “We now need to press ahead with exploring possibilities for tailoring treatment for a heart attack to an individual’s risk following a heart attack and testing whether drugs that improve clot lysis time can reduce this risk”.

The study received support from the British Heart Foundation.