Q. Limitations in the Diagnostic use of Stress Echocardiography?
Although the presence of coronary artery disease is readily recognised in the setting of multivessel disease, and multivessel pathology is readily recognised in the presence of prior infarction ("ischaemia at a distance"), the technique has a sensitivity of only 50 per cent for the recognition of multivessel disease in normal ventricles. The development of global ventricular dysfunction (reduction of ejection fraction or left ventricular enlargement) should increase the interpreter's suspicion of multi-vessel disease, although it may reflect loss of contractile reserve in valvar heart disease. Clues to the presence of extensive disease despite apparently localised wall motion abnormalities include the early onset of ischaemia, at a low heart rate and rate-pressure product, or at a low dose of pharmacologic stressor.
The detection of single vessel stenoses may also be problematic,and the sensitivity of stress echo for this problem is probably less than that of myocardial perfusion scintigraphy. Because of problems posed by identification of minor gradations of wall motion in the setting of abnormal function, the identification of ischaemia within areas of resting wall motion abnormalities may be difficult. The problem is probably less during dobutamine stress because ischaemic segments with abnormal resting function often show a biphasic response.