Usefulness of thallium-201 myocardial SPECT using dipyridamole infusion combined with low level exercise for the detection of the ischemic heart disease

To evaluate the usefulness of thallium-201 myocardial SPECT using dipyridamole infusion combined with low level exercise (Dp-method) for the detection of the ischemic heart disease, we performed both Dp-method and maximum physical exercise SPECT (Ex-method) in the same patients, and compared the results obtained by the two methods. In the visual evaluation, the detectability of each stenotic coronary territory by Dp-method tended to be higher than that by Ex-method (accuracy 71% vs 67%). The severity of the defect and the degree of the redistribution were higher by Dp-method than those by Ex-method. The washout rate (WR) analysis in 14 angina pectoris patients showed the detectability (accuracy) by Dp-method to be significantly higher than that by Ex-method (86% vs 64%; p<0.05). In comparison of mean WR values in normal subjects (10 cases for Dp-method and other 8 cases for Ex-method), mean WR by Dp-method was as high as that by Ex-method and the deviation of WR value among subjects was very small. This was probably due to the effect of the low level exercise. These results suggested that Dp-method was more excellent than Ex-method in the evaluation of the ischemic heart disease, and was a useful method of the daily routine work. The incidence of chest symptom and the electrocardiographic ST-depression was as high by Dp-method as that by Ex-method. The filling defects in Dp-method were thought to be induced not only by the difference in the relative increase of the myocardial perfusion, but also by the myocardial ischemia. (author)