Harvard Heart Letter

Crystallizing moment

Needle-like crystals of cholesterol could promote, trigger heart attacks.

What sets off a heart attack?

The steps leading up to one have been fairly well worked out: Cholesterol accumulating in patches along artery walls is attacked by white blood cells, eventually creating a gooey fluid covered by a skinlike cap. It often takes decades for these cholesterol-filled plaques to develop, and they can sit snugly in an artery wall for years. But what makes a plaque break open and leak its contents into the bloodstream, causing a clot that can block an artery supplying the heart (starting a heart attack) or brain (starting a stroke)?

No one really knows. It could be a spike of high blood pressure or the surge of chemical messages that accompany anger or stress. It could be the result of white blood cells that have been chewing through the plaque and are finally taking their last bites. Two Michigan State University researchers think that it could also be due to the action of crystallizing cholesterol.

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