DOBUTAMINE STRESS - EFFECTS ON REGIONAL MYOCARDIAL BLOOD-FLOW AND WALL-MOTION

Objectives. This investigation studied the relation between regional myocardial blood flow and left ventricular function during dobutamine stress in patients with coronary artery disease. Background. Dobutamine stress is becoming more frequently used as an alternative to dynamic exercise in patients with ischemic heart disease. Methods. We studied 12 patients with coronary artery disease. Dobutamine was infused from 5 mu g/kg body weight per min up to 40 mu g/kg per min or until chest pain or other intolerable side effects. Regional myocardial blood flow was measured with positron emission tomography and oxygen 15-labeled water, Regional wall motion was assessed in three short-aids slices by magnetic resonance imaging. Each slice was subdivided into four regions: septal, anterior, lateral and inferior. A total of 140 regions were suitable for comparison. Results. During stress, new wall motion abnormalities developed in 27 regions. Myocardial blood Bow (mean +/- SD) increased in 113 regions that did not develop wall motion abnormalities (0.98 +/- 0.26 [baseline] vs. 1.98 +/- 0.87 [dobutamine] ml/min per g, p < 0.001), whereas it did not change significantly in regions with stress-induced wall motion abnormalities (1.00 +/- 0.28 [baseline] vs. 1.30 +/- 0.62 [dobutamine] ml/min per g, p = NS). An absolute decrease in myocardial blood Bow below the value at rest was observed in seven segments that developed wall motion abnormalities during stress. Conclusions. The normal functional response to dobutamine stress is paralleled by an increase in coronary flow, whereas mechanical dysfunction is accompanied by a blunted increase, or even a paradoxic decrease, in regional coronary Bow.