DIPYRIDAMOLE IS SUPERIOR TO DOBUTAMINE FOR THALLIUM STRESS IMAGING - A RANDOMIZED CROSSOVER STUDY

To assess the value of dobutamine over dipyridamole as a pharmacologic al stressing agent in myocardial perfusion imaging with thallium-201. Design-Stress and redistribution tomographic images were taken in a gr oup of patients in a randomised crossover study of both agents. The sc ans were scored to give a value for the stress and redistribution imag es and a reversibility score (redistribution - stress). All patients h ad coronary angiography that scored. Differences between agents were c ompared by a paired t test. Patients-30 patients aged 51-70 years with chest pain thought to be caused by myocardial ischaemia. 11 had had p revious myocardial infarction. Results-Dipyridamole caused adverse sym ptoms in six patients whereas dobutamine caused symptoms in 21 patient s (chi(2) = 15 15, p < 0.0001). Dobutamine stress took considerably lo nger than dipyridamole (31 v 6 minutes) and cost more (pound 17 v poun d 1.50). There were no significant differences between the agents in t erms of total stress or redistribution scores, but regional analysis s howed that dipyridamole showed significantly more defects during stres s at the apex and lateral wall (p < 0.05), with no significant differe nce at redistribution. Dipyridamole stress also caused significantly m ore reversible defects at the apex (p < 0.05) and gave a better correl ation than dobutamine with coronary score (dipyridamole r = 0.80, p < 0.001 v dobutamine r = 0.64, p < 0.001). In six patients who had conti nued to take beta blockers the results of dobutamine stress did not co rrelate with coronary score, r = 0.34 (NS), whereas dipyridamole studi es were not affected. Conclusion-Compared with dobutamine, dipyridamol e was as effective in producing overall perfusion defects and more eff ective in provoking defects at the apex and lateral segment. The dipri damole study correlated better with coronary score and was not affecte d by concurrent beta blocker treatment. It was also better tolerated b y the patients, was less time consuming, and was much cheaper.