Assessment of viable myocardium by dobutamine transesophageal echocardiography and comparison with fluorine-18 fluorodeoxyglucose positron emission tomography.

OBJECTIVES

The aim of this study was to assess whether dobutamine transesophageal echocardiography can identify viable myocardium in patients with chronic myocardial infarction.

BACKGROUND

Experimental and clinical studies have shown that dobutamine can recruit a contraction reserve in postischemic viable but akinetic segments, indicating that dobutamine-induced functional recovery is a potential ultrasound marker of myocardial viability.

METHODS

Forty patients underwent rest and dobutamine transesophageal echocardiography (dobutamine 5, 10 and 20 micrograms/kg body weight per min) and fluorine-18 (F-18) fluorodeoxyglucose positron emission tomography at rest. Three representative short-axis tomograms and a transverse four-chamber-view were used for wall motion and F-18 fluorodeoxyglucose-uptake analysis in corresponding myocardial regions. A basally asynergic segment was considered viable by transesophageal echocardiography if dobutamine-induced systolic wall motion could be observed. Viability by positron emission tomography was defined as F-18 fluorodeoxyglucose uptake > or = 50% of the maximal uptake in a region with normal wall motion by left ventriculography.

RESULTS

Functional recovery within the infarct region was found in 21 (53%) of 40 patients during dobutamine infusion. Infarct region-related viability by F-18 fluorodeoxyglucose uptake was diagnosed in 25 (63%) of 40 patients, yielding a diagnostic agreement between both techniques in 90% of patients. In 210 (89%) of 235 akinetic segments at rest, data on myocardial viability were concordant by the two techniques. The positive and negative predictive accuracy of dobutamine transesophageal echocardiography for viability defined by F-18 fluorodeoxyglucose uptake was 81% and 97%, respectively. Such uptake was significantly different (p < 0.001) between segments remaining akinetic (mean +/- SD 45 +/- 9%) during dobutamine infusion and segments with a dobutamine-induced contraction reserve (68 +/- 11%).

CONCLUSIONS

Dobutamine transesophageal echocardiography provides a promising low cost and widely available approach to unmask myocardial viability in patients with chronic myocardial infarction, and results compare favorably with those of F-18 fluorodeoxyglucose positron emission tomography.