About 10 million people have heart attacks every year worldwide. Although improvements have been made in emergency treatment, the risks of early death and repeat heart attack remains high. Previous studies have shown that clopidogrel adds to the benefit of aspirin in acute coronary syndromes without ST-segment elevation*. However, clopidogrel's effect on major heart attack patients with ST-elevation has been unclear until now.
Zhengming Chen (University of Oxford, UK) and colleagues recruited over 45,800 patients with onset of heart attack from 1250 hospitals in China into the study. The investigators randomly allocated patients to 75 mg clopidogrel daily or placebo, in addition to daily aspirin (as well as other standard treatments) until they were discharged or had spent up to 4 weeks in hospital. 93% of patients had ST-segment elevation and 7% had ST-segment depression. The researchers found that clopidogrel reduced deaths, repeat heart attacks, and stroke by 9% when compared with placebo, and led to a 7% reduction in deaths alone. They also found that patients allocated clopidogrel had a 14% reduction in repeat heart attacks during the scheduled treatment period. The results also show that the treatment is safe, with no apparent increase in life-threatening bleeding.
Dr Chen concludes: "If early clopidogrel therapy was given in hospital to just 1 million of the 10 million patients who have a heart attack every year then it would, on present evidence, prevent about 5000 deaths and 5000 non-fatal reinfarctions and strokes. Moreover, continued treatment with clopidogrel after hospital discharge could lead to further net gains, although the benefits and hazards of more long-term therapy are still under investigation."
In a second part of the study, also published in this week's issue, the group looked at the effect of giving patients early intravenous then oral metoprolol (beta-blocker therapy) in the emergency treatment of heart attacks. The team found that the treatment could cut the relative risk of repeat heart attack and of ventricular fibrillation** by about 15-20%, but increased the risk of cardiac shock by 30%, especially during the first day or so after admission. The authors' state that to maximise the benefits and minimise any potential hazard, it may generally be prudent to wait until a heart attack patient's condition has stabilised before starting beta-blocker therapy.
See also accompanying comment.
Contact: Dr Zheng-Ming Chen, Clinical Trial Service Unit (CTSU), Richard Doll Building, Old Road Campus, University Oxford, OXFORD, OX3 7LF, UK.T) 01865743 839 / 07917771693 (mobile) zhengming.chen@ctsu.ox.ac.uk or Professor Rory Collins at the CTSU T) 01865-743 743 secretary@ctsu.ox.ac.uk
Notes to editors
*ST-segment elevation refers to a change recorded by an electrocardiogram (ECG) during chest pain.
**Ventricular fibrillation is when the heart rhythm is disturbed, causing it to fibrillate (quiver) in a disordered way.
Journal
The Lancet