Should We Treat Silent Ischaemic?

24-hour ambulatory monitoring of the ST segment in patients with angina has shown that ST segment depression may be accompanied by angina pectoris, but it occurs equally often without any symptoms. Approximately half of all episodes of ST segment depression are accompanied by chest pain. Doubt has been expressed as to the significance of ST segment changes that occur in the absence of chest pain, but haemodynamic studies and nuclear imaging have shown that such changes are accompanied by alterations in left ventricular filling pressure. Ambulatory pulmonary artery monitoring has also shown that silent ST segment depression is accompanied by a significant increase in pulmonary artery diastolic pressure, and this does not differ from painful episodes of ST segment depression. Studies using ambulatory monitoring have shown that antianginal drugs are capable of reducing the frequency of ST segment depression accompanied by pain. We have recently performed studies investigating the use of antianginal medications; i.e. beta-blocking drugs with and without sympathomimetic activity, alpha-beta-blocking drugs, calcium antagonists and nitrates in the treatment of both painful and painless ST segment depression. These studies have shown that the effect of these drugs on painless episodes is similar to their effect on painful episodes of myocardial ischaemia. Although the prognostic implications of silent ischaemia and the importance of these therapeutic findings are unknown, it is well known that approximately one-quarter of all myocardial infarctions occur without chest pain. Moreover, recent investigations in unstable angina show that silent myocardial ischaemia is an important predictor of future coronary events.