Prognostic implications of silent ischemia in patients with stable angina pectoris

Summary

Twenty-four-hour ambulatory monitoring of the ST segments coupled with hemodynamic and radionuclide studies in patients with angina has shown that silent myocardial ischemia is frequent. Hemodynamic studies, nuclear imaging and ambulatory pulmonary artery monitoring has shown that silent ST segment depression is accompanied by alterations in left ventricular filling pressure and alterations in myocardial perfusion very similar to those seen during angina pectoris. Whilst the prognostic implications of silent ischemia are unknown, circumstantial evidence would suggest that silent ischemia is important. Long term follow up studies have shown that silent ischemia in completely asymptomatic subjects is associated with subsequent death and the development of symptoms. Approximately one quater of all myocardial infarctions occur without chest pain and half of these are completely silent; the long term outlook from silent myocardial infarction does not differ form infarction accompanied by chest pain. Finally, recent investigations in unstable angina show that silent myocardial ischemia is an important predictor of future coronary events.

Thus, silent ischemia should not be considered in any way different to angina pectoris in terms of prognosis. The mechanisms responsible for producing silent ischemia do not differ from angina and in any one patient the pathophysiological mechanism may change depending on the stage of the disease. Therapeutic approaches should not be confined to simply alleviating silent ischemia in patients with chronic stable angina, but should be aimed at preventing the subsequent probable outcomes, i.e., sudden death, unstable angina and myocardial infarction.