Implication of the negative U wave during dobutamine stress echocardiography

Although the development of negative U waves during exercise is a highly specific marker for detecting coronary artery disease, their assessment during exercise is difficult. The clinical significance of the negative U wave during dobutamine stress echocardiography was investigated in 181 patients who had suspected coronary artery disease. Dobutamine-induced negative U waves appeared in 28 patients (16%) during dobutamine infusion. Coronary angiography showed coronary artery disease in 114 of the 181 patients. The sensitivity and specificity of the negative U wave for detecting coronary artery disease were 22 and 96%, respectively, while the corresponding values for ischemic ST-T changes were 49 and 76%, respectively. The negative U wave appeared during low-dose infusion of dobutamine (5-10 microg/kg/min) in 82% of the patients with this wave. In the 21 patients who had both a negative U wave and an inducible regional wall motion abnormality during dobutamine infusion, the development of the negative U wave was either simultaneous with or earlier than that of the wall motion abnormality. Although its sensitivity was low, the negative U wave during dobutamine stress echocardiography is a highly specific marker for detecting coronary artery disease. Because of its earlier appearance as compared with that of the wall motion abnormality, the dobutamine-induced negative U wave may be considered to be an early and useful adjunctive sign for detecting coronary artery disease during dobutamine stress echocardiography.