Low-dose dobutamine imagings predicting regional improvement in left ventricular function after revascularization

ments capable of recovering function was comparable between lowdose dobutamine echocardiography and ventriculography. Left ventriculography was performed only in the 30° right anterior oblique projection, which may not cover all the segments of the left ventricle. Left ventriculography was performed only after a 10-␮g/kg/min dobutamine infusion, which may be responsible for a false-negative result (17%). This is due to the fact that some segments of the left ventricle may improve at the end of a 5-␮g/kg/min dobutamine infusion, but deteriorate at the end of a 10-␮g/ kg/min dobutamine infusion. The authors concluded that this imaging technique may provide an advantage over low-dose dobutamine echocardiography in patients with suboptimal echocardiographic visualization. New echocardiographic technology, which was not used in this study, has been developed. Second harmonic imaging and ultrasound contrast agents have been used to enhance image quality during dobutamine echocardiography.2 Although this technique improves the image quality of echocardiography, 5% to 10% of patients undergoing stress echocardiography still have poor acoustic windows.3 Cine-magnetic resonance imaging (MRI) has been used to produce images that provide visualization of cardiac motion very similar to

echocardiography. Hundley et al.4 demonstrated that dobutamine MRI was an excellent noninvasive technique for providing better visualization of wall motion in patients who have poor acoustic windows on harmonic imaging. Myocardial viability has been evaluated by cine-MRI. Baer et al5 compared [18F]fluorodeoxyglucose positron emission tomography (18FDG PET) with low-dose dobutamine cine-MRI in 35 patients with chronic myocardial infarctions and persistent wall motion abnormalities. Left ventricular myocardium was considered to be viable if either the baseline wall thickness was ⱖ5.5 mm or if the wall thickened by ⱖ1 mm in response to dobutamine. They found a sensitivity of 88%, specificity of 87%, and positive predictive value of 92% for identifying viable myocardium in the infarct zone by using these criteria. Forty-three patients with chronic myocardial infarctions and persistent wall motion abnormalities were evaluated for viable myocardium by dobutamine transesophageal echocardiography and dobutamine cineMRI compared with 18FDG PET. The sensitivity and specificity for detecting 18FDG PET-defined viable myocardium were 77% versus 81% and 94% versus 100% for transesophageal echocardiography and MRI, respectively.6

Left ventriculography is an invasive procedure and the patient may require an extra 40 to 80 ml of contrast. In patients who have poor acoustic windows on harmonic imaging or after using ultrasound contrast agents, the cine-MRI technique should be considered before considering an invasive test. Pairoj Rerkpattanapipat,

MD

Winston-Salem, North Carolina 30 August 2000 1. Vecchia LD, Storti T, Cogliati C, Guzzetti S, Danna P, Scrofani R, Di Biasi P, Malliani A. Comparison of low-dose dobutamine ventriculography with low-dose dobutamine echocardiography for predicting regional improvement in left ventricular function after coronary artery bypass grafting. Am J Cardiol 2000;86:371–374. 2. Clark LN, Dittrich HC. Cardiac imaging using optison. Am J Cardiol 2000;86:14G–18G. 3. Geleijnse ML, Fioretti PM, Roelandt JR. Methodology, feasibility, safety and diagnostic accuracy of dobutamine stress echocardiography. J Am Coll Cardiol 1997;30:595– 606. 4. Hundley WG, Hamilton CA, Thomas MS, Herrington DM, Salido TB, Kitzman DW, Little WC, Link KM. Utility of fast cine magnetic resonance imaging and display for the detection of myocardial ischemia in patients not well suited for second harmonic stress echocardiography. Circulation 1999; 100:1697–1702. 5. Baer FM, Voth E, Schneider CA, Theissen P, Schicha H, Sechtem U. Comparison of low-dose dobutamine-gradient-echo magnetic resonance imaging and positron emission tomography with [18F]fluorodeoxyglucose in patients with chronic coronary artery disease. A functional and morphological approach to the detection of residual myocardial viability. Circulation 1995;91:1006 –1015. 6. Baer FM, Voth E, LaRosee K, Schneider CA, Theissen P, Deutsch HJ, Schicha H, Erdmann E, Sechtem U. Comparison of dobutamine transesophageal echocardiography and dobutamine magnetic resonance imaging for detection of residual myocardial viability. Am J Cardiol 1996;78:415– 419. PII S0002-9149(00)01350-3

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