Silent myocardial ischaemia is found in 5% of a completely symptom-free population, in 30% of patients with a history of myocardial infarction and in 60 to 100% of patients with stable or unstable angina pectoris. Only one fifth to one quarter of episodes of myocardial ischaemia is associated with angina pectoris which means that 75% to 80% of episodes take a silent course. Episodes of myocardial ischaemia take place at lower heart rates than during exercise test and they are induced by common, everyday activities of the patient. So far it is not known why some episodes of myocardial ischaemia are silent while others are associated with angina pectoris. No differences were found in the duration or extent between silent or symptomatic myocardial ischaemia. Patients with frequent episodes of silent myocardial ischaemia have in general an elevated threshold of pain perception. A certain role is probably also played by the increased secretion of endogenous opioids--endorphins. The finding of myocardial ischaemia during ambulatory monitoring of ECG is of prognostic value regardless whether ischaemia is associated with angina pectoris. This applies in patients with unstable angina pectoris where ST depressions may be found during Holter monitoring of the ECG even when pain is controlled by treatment, and this finding is associated with more serious coronarographic findings and a poorer prognosis. The position is similar in patients with stable angina pectoris where episodes of depression of the ST segment during ambulatory ECG monitoring are associated with a poorer prognosis and this finding does not depend on the result of the electrocardiographic exercise test.(ABSTRACT TRUNCATED AT 250 WORDS)

Keywords: Humans; Myocardial Ischemia /diagnosis/