After a heart attack, much of the damage to the heart muscle is caused by inflammatory cells that rush to the scene. But that damage is slashed in half when microparticles are injected into the bloodstream within 24 hours of the attack, reports new research. The heart lesion was reduced by 50 percent and the heart could pump significantly more blood as a result of the microparticles. The new therapy has the potential to transform the way heart attacks are treated.