Clinical importance of silent ischemia

Objective signs of myocardial ischemia without angina pectoris or its equivalents define the syndrome of silent myocardial ischemia. Its significance lies in the prevalence and prognostic implications. As a prevalence, asymptomatic coronary heart disease can be found in 2.5% of men 40 to 60 years old. Silent myocardial ischemia is frequently found in patients with unstable coronary syndromes. The Framingham Study showed 25% of all myocardial infarctions as unrecognized by patients and physicians. The prognostic implications of silent myocardial ischemia are shown in large studies on prognosis of pathologic exercise-ECG's. Asymptomatic patients with pathologic exercise-ECG have always been recognized as having a significantly increased risk of myocardial infarction and death. Recently, many studies showed a worse prognosis for patients with asymptomatic transient ischemia on Holter-ECG. This can be found in patients with stable angina pectoris, unstable angina pectoris, patients with peripheral arterial disease, and patients after myocardial infarction. It becomes clear that prognosis is not defined by the pain, but by the severity of ischemia. Silent ischemia has to be viewed together with the severity of the underlying coronary heart disease. This synopsis will define the necessary steps for further diagnosis and treatment.