Myocardial Viability Assessment with Dobutamine Radionuclide Ventriculography : Correlation with Dobutamine Echocardiography

The identification of viable myocardium is an important consideration for patient selection prior to coronary interventional procedures, especially in patients with severe left ventricular (LV) dysfunction. This case reported is a 62-year-old male with chronic coronary artery disease and severe LV dysfunction. He had an acute anterior myocardial infarction 11 years ago and had undergone coronary bypass surgery one year later. Crescendo effort angina occurred since 7 months prior to admission and became refractory to medical therapy gradually. The coronary angiogram showed total occlusion of the left anterior descending artery (LAD) and its first diagonal branch, patent graft to the right coronary artery (RCA) , and severe lesion deterioration of the native vessels, that included total occlusion at the proximal LAD and proximal RCA, 80% diffuse narrowing in the proximal left circumflex artery ( LCx) and 80% discrete stenosis in the distal RCA. There was far collateral flow to the LAD from the very proximal RCA. The resting equilibrium radionuclide ventriculogram (RVG) using Tc-99m pertechnetate in 45-degree left anterior oblique projection revealed hypokinesia of posterolateral wall, akinesia of septum and inferoapical wall, and an ejection fraction (EF) of only 12.1%. The repeated equilibrium RVG in the same projection performed during low- dose dobutamine (10μg/kg/min) infusion for 5 minutes disclosed improved motion in the posterolateral wall and septum, and a small increase in EF ( 16.8%). The dobutamine ( 10μg/kg/min) stress echocardiogram demonstrated enhanced systolic motion and thickening of the myocardium supplied by the LCx, LAD and distal RCA, which indicated the presence of viable myocardium . Thus, the application of dobutamine radionuclide ventriculography may be a potentially exciting approach to assessmant of viable myocardium