Comparison of intravenous dipyridamole and adenosine Tc-99m MIBI myocardial imaging for detection of coronary artery disease

A total of 44 patients referred for Tc-99m MIBI myocardial imaging for detection of coronary artery disease (CAD) were studied to compare the differences in heart beat, blood pressure, electrocardiographic changes and side effects during intravenous infusion of dipyridamole (ID) and adenosine (IA) and also to determine the degree of concordance between ID and IA Tc-99m MIBI imaging. These patients were divided into two groups: 20 suspected CAD patients constituted group I and 24 proven CAD patients formed group II. All patients received ID 0.56 mg/kg for 4 min and within about 10 days IA 0.14 μg/kg/min for 6 min with Tc-99m MIBI imaging. The results revealed that maximal heart beat increased and maximal systolic blood pressure decreased in both IA and ID patients with no statistically significant differences. Transient second degree AV block occurred with IA in 3 patients. Side effects, such as, chest pain, headache, dizziness and shortness of breath occurred more often and were in general more intense in IA patients, but they were typically mild and resolved spontaneously within 1 or 2 min of discontinuation of IA. Both IA and ID Tc-99m MIBI imaging were normal in 18 of 20 group I patients and were concordant for the presence of perfusion defects in the other 2 patients. Of 24 group II patients, all had myocardial perfusion defects on both tests and were concordant for the severity of the perfusion abnormalities. However, in one patient each, IA and ID Tc-99m MIBI imaging were preferred over the other. In conclusion, both IA and ID Tc-99m MIBI myocardial imaging show good agreement for evaluation of CAD.