Silent myocardial ischemia.

ST-segment depression in the absence of symptoms is now a well-defined abnormality in patients with coronary artery disease. ST-segment depression without the occurrence of angina is a marker for myocardial perfusion defects and ischemia. During 24-hour recordings, most episodes of ischemia in patients with coronary artery disease are silent and occur with relatively normal heart rates. The combination of silent ischemia and ischemia associated with angina is referred to as total ischemic burden. Silent ischemia is prognostically important for identifying patients in whom subsequent myocardial events may develop. The episodes of silent ischemia, and thus total ischemic burden, can be reduced by standard antianginal therapy, a measure that may have a favorable influence on patient outcome. Proof that reduction of the total ischemic burden actually improves outcome, however, is not yet available.