The accuracy of echocardiography during the infusion of low-dose dobutamine in identifying vital myocardium in patients with obstructive coronary disease and chronic left ventricular dysfunction

The identification of viable myocardium has important therapeutic implications in patients with coronary artery disease (CAD) and chronic left ventricular dysfunction. To assess the accuracy of transthoracic echocardiography (TTE) during dobutamine infusion for identification of viable myocardium, we have analyzed 14 patients affected by CAD and chronic abnormalities of left ventricular wall motion (RWM), present at rest, referred for coronary artery bypass grafting (CABG): 8 of 14 patients had a history of myocardial infarction with evidence of Q waves at the surface ECG. All patients had a clinical stable CAD. RWM response to dobutamine (5 mcg/kg/min and 10 mcg/kg/min) was evaluated using TTE and compared to RWM changes after CABG analyzed by intraoperative epicardial echocardiography (EE). RWM was analyzed qualitatively by dividing the left ventricle into 16 segments and a score index was assigned to each region (0: normal; 1: hypokinetic; 2: akinetic; 3: dyskinetic). Of 125 akinetic segments present at rest before CABG, 93 showed functional improvement after CABG at intraoperative EE. The RWM response to dobutamine infusion predicted intraoperative improvement after CABG in 85 of 93 segments (sensitivity: 91.3%) and identified 25 of the 32 segments which did not exhibit intraoperative improvement (specificity: 78.1%). The TTE performed 15 days after CABG showed no worsening or further improvement in RWM when compared with intraoperative EE study. Summed segment scores in 14 patients showed significantly improvement from 17.9 +/- 7, medium values at rest, to 5.1 +/- 4 after dobutamine infusion (p less than 0.001) and 5 +/- 7 after CABG (p less than 0.001).