A simple blood test can help identify healthy people most likely to have a heart attack or stroke years before classic warning signs appear, new research suggests, lending support to a radical new theory about the underlying causes of these leading killers. The findings indicate that hardened and narrowed arteries, which typically precipitate heart attacks and strokes, are caused by inflammation in blood vessel walls -- the same kind of reaction that triggers redness and swelling when a cut gets infected.

Researchers cautioned that it was too soon to recommend widespread use of the test, which looks for a substance called C-reactive protein, a general indicator of inflammation. But its ability to identify as many as eight years in advance those most likely to have a heart attack or stroke supports the unorthodox notion that inflammation is an even more fundamental cause of hardening of the arteries than is high cholesterol or elevated blood pressure.

The standard view on heart attacks and strokes is that high levels of cholesterol and fat in the blood, and high blood pressure, can cause fatty deposits to line blood vessel walls -- a condition called atherosclerosis. Eventually, a blood clot becomes lodged in that narrowed vessel, cutting off the supply of oxygen to the heart or brain.