Syndrome X--angina and normal coronary angiography.

It is clear that angina pectoris with normal coronary arteries is a heterogeneous and ill-defined syndrome that encompasses different pathogenic entities. Differences in patient selection and in definition of 'syndrome X' has made comparison between different study groups rather difficult. Two decades of investigations have not revealed a specific cause of this syndrome. There is now a general belief that syndrome X probably encompasses several pathophysiological disease entities and the mechanisms involved in syndrome X remain to be fully elucidated.