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)?