The effect of
nicorandil on myocardial perfusion in
ischemic heart disease was studied using exercise-load Tl-201 myocardial SPECT (Ex-SPECT). ExSPECT was carried out in 12 patients with previous
myocardial infarction (OMI) and 9 with
angina pectoris (AP) before and after administration of
nicorandil 15 mg/day, for three or more weeks; %Tl uptake and the washout rate in infarcted or ischemic areas were calculated from short axial images using the Bull's eye method. In the OMI group, %Tl uptake and washout rates in the
infarction areas improved significantly from 52.4% and 0.25 before
nicorandil to 60.4% and 0.38 after
nicorandil. In the AP group, too, %Tl uptake and washout rates showed a significant improvement from 56.9% and 0.10 before to 69.1% and 0.33 after administration of
nicorandil. Six subjects who had not received the
drug, and who showed negative washout rates, had high improvement rates when
nicorandil was administered, suggesting that the
drug could increase myocardial perfusion during exercise loading as well as suppressing coronary
spasm. Ex-SPECT was carried out in 4 subjects before and after the administration of nicarandil and after subsequent surgical treatment (PTCA or CABG) and the effects of the two
therapies were compared. The washout rate was improved from 0.01 to 0.34 by the administration of
nicorandil, and a notable increase in coronary artery blood flow was achieved compared to the level after surgical treatment, i.e. 0.50. It is concluded that normal dosages of
nicorandil have a powerful direct effect of dilating the coronary arteries without any influence on preload or afterload.