DOBUTAMINE THALLIUM MYOCARDIAL PERFUSION TOMOGRAPHY

Dobutamine has favorable properties for the pharmacologic manipulation of myocardial oxygen demand in the provocation of ischemia during the investigation of coronary artery disease. The value of dobutamine infusion for thallium myocardial perfusion tomography was assessed in 50 patients with exertional chest pain undergoing coronary arteriography. Dobutamine was infused in 5-min stages at incremental rates from 5 to 20-mu-g/kg per min or until limited by symptoms. The myocardium was divided into nine segments for analysis of perfusion. Thirty-nine of 40 patients with coronary artery disease had a reversible perfusion defect demonstrated by dobutamine thallium tomography (sensitivity 97%) and 8 of 10 patients with normal coronary arteries had normal myocardial perfusion (specificity 80%). These values were significantly better than the sensitivity and specificity of exercise electrocardiography (78% and 44%, respectively; p < 0.01). There was a significant relation between the mean number of segments with abnormal perfusion and the number of diseased coronary vessels (0.6, 2.6, 4.4 and 6 segments in zero-, one-, two- and three-vessel disease, respectively; p < 0.001). There was also a significant relation between the maximal tolerated dose of dobutamine and the treadmill exercise time (r = 0.56, p < 0.001), but a wide range of exercise times was achieved in the 15- and 20-mu-g per min groups, principally because of exercise limitation by noncardiac symptoms. Dobutamine infusion was well tolerated in all patients, including six with asthma. There were no significant arrhythmias or limiting symptoms other than chest pain. Dobutamine thallium myocardial perfusion tomography is a useful technique for the detection, localization and assessment of myocardial ischemia, particularly when exercise potential is limited. Both the safety of dobutamine in asthmatic patients and the relation between achieved dose and exercise time represent advantages over the use of adenosine or dipyridamole.