Objectives: We sought to assess the ability of the "biphasic" response (i.e., initial improvement in wall thickening followed by reduced wall thickening) during serial dobutamine stress echocardiography to detect ischemia in patients with a wall motion abnormality. Furthermore, we compared the power of the biphasic echocardiographic response with that of myocardial perfusion imaging for the detection of myocardial ischemia.
Background: Stress echocardiography has been shown to be less sensitive than radionuclide perfusion imaging for detecting ischemia in patients with a wall motion abnormality. Peak stress wall thickening in such areas may not give a full account of the intermediate changes, whereas initial improvement (the biphasic response) may enhance diagnosis.
Methods: Patients with a wall motion abnormality and documented coronary artery disease underwent simultaneous graded dobutamine (5 to 40 micrograms/kg body weight per min) stress echocardiography and radionuclide perfusion imaging with single-photon emission computed tomography using either technetium-99m sestamibi or technetium-99m tetrofosmin. Semiquantitative analyses of image groups were performed in blinded manner by two separate groups of observers.
Results: Myocardial ischemia was detected by perfusion imaging in 45 of the 54 patients. High dose dobutamine echocardiography detected ischemia in only 25 (56%) of these patients. However, when the biphasic response was taken into account, ischemia was detected in 44 (98%) of the 45 patients (p < 0.001). Agreement between radionuclide imaging and echocardiographic findings for the detection of ischemia was significantly enhanced (p = 0.03) when the biphasic response was used (89%, kappa = 0.51) instead of high dose stress dobutamine echocardiography (56%, kappa = 0.10).
Conclusions: The detection of myocardial ischemia may be significantly enhanced by utilizing the biphasic response during serial stress dobutamine echocardiography in patients with a wall motion abnormality.