ABSTRACT
Introduction The number of patients investigated by coronary angiography each year in the UK is 1600 per million.1 The figure is less than in other European countries and in the USA where as many as 4000 per million people are investigated each year. The proportion of patients in whom the angiogram is normal and shows no significant stenoses is overall 15-20% (Table 16.1), but this hides important sex differences. The incidence of normal coronary angiogram is less in men, around 13%, and as high as 55% in women.2,3 The explanation of this difference is uncertain. It is likely that the greater incidence of normal tests reflects a failure to take into account prior probability and risk factors before listing for angiography.4
