Key words: silent myocardial ischemia - diagnosis and treatment, diabetes mellitus

Silent myocardial ischemia (SMI) is defined as the presence of objective evidence of myocardial ischemia in the absence of chest discomfort or other anginal equivalents. Most silent ischemic episodes occur during minimal or no physical exertion. The exact reasons for the development of angina during some episodes of myocardial ischemia and the absence of symptoms during other episodes are not known. Some mechanisms include inability to reach pain threshold during an episode of ischemia, lesser severity and shorter duration of ischemic episodes, presence of higher threshold for pain, generalized defective perception of painful stimuli and presence of a defective anginal warning system. Coronary artery disease (CAD) is the major cause of morbidity and mortality in patients with diabetes. CAD is usually more advanced at the time of diagnosis and has unfavorable prognosis in diabetic patients. Later diagnosis of CAD may be explained by the presence of SMI, which is more frequent in patients with diabetes (probably because of diabetic neuropathy). The prevalence of SMI is 10%-20% in diabetic patients versus 1%-4% in nondiabetic patients. Exercise treadmill test (ETT) and ambulatory (Holter) monitoring are the most readily available and frequently used tests to identify SMI in clinical practice. The exact reason for unfavorable prognosis associated with SMI is not known. It is possible that repeated episodes of SMI could lead to progressive fibrosis and development of left ventricular dysfunction, and to life-threatening arrhythmias, especially in patients with an electrical substrate for arrhythmias. SMI is associated with an increase in coronary risk that may be reversible with appropriate therapy.