[Detection and prognostic value of silent myocardial ischemia]

Silent myocardial ischaemia (SMI) is a common manifestation of coronary artery disease. Continuous electrocardiographic recordings have shown that 75% of ischemic episodes are asymptomatic. In addition, SMI has the same consequences as symptomatic ischaemia on myocardial perfusion and ventricular function. There are many means of detecting SMI, continuous electrocardiographic monitoring, exercise stress testing with or without methods of analysis of myocardial perfusion or wall motion using radioactive tracers or echocardiography. The latter techniques seem to improve the sensitivity of exercise stress testing. More recently, pharmacological stress testing coupled with myocardial scintigraphy or echocardiography has been introduced. In coronary patients, the prevalence of SMI on Holter monitoring is about 50% in angina and 25% after myocardial infarction. The prognostic value of SMI has been the object of much research. In asymptomatic patients with documented coronary artery disease, SMI is associated with a relative risk of a cardiac event 2 to 3 times greater than that of subjects without ischaemia. In angina pectoris, the relative risk of future cardiac events is 5.3 times greater, and that of death is 2.3 times greater. These results reported with the Holter method have been confirmed by those of exercise stress testing with and without coupled imaging techniques. In unstable angina, the results are the same: the relative risk of cardiac events in patients with SMI on Holter monitoring is increased by a factor of 4.5, and that of death by a factor of 4. This increased risk is also observed after myocardial infarction whether SMI is recorded by Holter monitoring or exercise stress testing. However, these observations are not confirmed in all reports.(ABSTRACT TRUNCATED AT 250 WORDS)