Cardiovascular disease, including coronary heart disease, strokes and diseases of other arteries, is a major cause of early death and disability. For many years the major markers of disease risk have been well recognised: these include high blood cholesterol levels and smoking. But it has also been recognised that these markers do not account for all cardiovascular risk. Furthermore, treatments that are highly effective in altering these markers, for instance the ‘statin’ drugs used to lower cholesterol, do not remove risk entirely: typically they reduce it by about 30% or less. These observations have prompted a search for other, perhaps more subtle, indicators of risk of.