Silent Ischaemia: Pathophysiological, Prognostic and Therapeutic Indicators in Chronic Stable Angina

Abstract

A vast quantity of literature has accumulated over recent years describing the activity of ischaemic heart disease outside the hospital environment in patients with coronary disease. This has been made possible with the introduction of ambulatory monitoring systems which accurately record and display the ST segment. As might be expected, there is disagreement about certain issues relating to the whole question of “ischaemia”, however, some observations about ischaemia in the ambulatory setting in coronary patients are now almost universally agreed upon. A significant proportion of patients with stable angina have episodes of transient ischaemia during their daily lives, despite the fact that most are receiving standard antianginal therapy. The majority of these episodes of transient ischaemia occur in the absence of angina — they are “silent”. Transient ischaemic episodes, both silent and painful, occur more frequently in patients with more severe coronary artery disease, and occur predominantly in those with a positive exercise test for ischaemia, and especially when the exercise test is positive at low work loads. Silent and painful episodes of ischaemia are characteristically similar in the ambulatory setting; what is not known is why silent ischaemia is silent.