Assessment of left ventricular wall motion and delineation of the endocardial border after intravenous injection of InfosonTM during dobutamine stress echocardiography

OBJECTIVES: To investigate whether intravenous injection of Infoson facilitates the assessment of left ventricular wall motion and definition of endocardial border and thereby reduces inter- and intra-observer variability during dobutamine stress echocardiography. BACKGROUND: Clear detection of the endocardial border is essential during dobutamine stress echocardiography. Although several contrast agents have been tested for their efficacy in enhancing definition of left ventricular endocardium, their usefulness during dobutamine stress echocardiography has not been evaluated. METHODS: Thirty coronary artery disease patients underwent dobutamine stress echocardiography. Infoson was injected at 0.2 ml/kg in both apical four- and two-chamber views. Detection of the left ventricular endocardial borders was scored from 0 (undetectable) to 10 (best) and expressed as a percentage of image quality at rest and peak stress by two independent observers. Regional wall motion was also evaluated and the total wall motion score index calculated each time. RESULTS: Delineation of the left ventricular endocardium improved from 76 +/- 4% to 84 +/- 2% at rest (P < 0.01) and from 75 +/- 4% to 89 +/- 1% at peak stress (P < 0.01) after administration of Infoson. The greatest improvement was seen in the basal and middle regions of the lateral and anterior walls. Inter- and intra-observer variability was reduced after administration of Infoson. At rest, the probability of concordance between two observers increased from 0.86 (0.82-0.89) to 0.91 (0.88-0.94) (P < 0.05) and at peak stress from 0.86 (0.82-0.9) to 0.90 (0.86-0.92) after administration of Infoson (P < 0.05). The probability of concordance between on- and off-line assessment by one observer also increased from 0.84 (0.8-0.88) to 0.90 (0.86-0.93) (P < 0.01) at rest and from 0.90 to 0.92 (NS) at peak stress. Overall, a change in wall motion score index occurred in 16 of 30 (53%) patients after administration of Infoson, thus improving the accuracy of the stress test compared with coronary angiography. The wall motion score index was overestimated in 11 of 16 (37%) patients without Infoson while the detection of new wall motion abnormalities increased in 5 of 16 (17%) (P < 0.01). CONCLUSIONS: Intravenous administration of Infoson facilitates the assessment of wall motion, particularly of the basal lateral and anterior walls where endocardial border drop-out frequently occurs during dobutamine stress echocardiography; it thus reduces the inter- and intra-observer variability.