Should we treat silent ischaemia?

Twenty-four hour ambulatory monitoring of ST segments in patients with angina has shown that ST-segment depression may occur accompanied by angina pectoris or equally frequently in the absence of symptoms. Approximately one-third of all episodes of ST-segment depression are accompanied by chest pain. Doubt has been expressed as to the significance of ST-segment changes occurring 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 that these do not differ from painful episodes of ST-segment depression. Studies using ambulatory monitoring have demonstrated that antianginal drugs, angioplasty, and surgery are capable of reducing not only the frequency of ST-segment depression accompanied by pain, but also painless ST-segment changes. Further studies are necessary to determine whether prognosis is improved by treating these silent episodes of myocardial ischaemia.