Increased redistribution of 99mTc-MIBI under the action of nitrate administration--a good tool for detection of myocardial vitality in patients with severe CAD.
BACKGROUND
The purpose of the study was to investigate and assess patients with severe, coronarographically documented coronary artery disease (CAD), previous myocardial infarction and left ventricular dysfunction, using radionuclide method for myocardial perfusion scintigraphy with 99mTc-MIBI and nitrate administration for detection of viable myocardium.


METHODS
We investigated 56 patients (37 male, 19 female, mean age 58 +/- 8 years) with CAD and previous myocardial infarction, mean EF 38% +/- 12; divided into 2 groups: Group I--28 patients, investigated at rest, i.v. injected 370 MBq (99m)Tc-MIBI, scintigraphy performed at 30 min and 4th hour; Group II--28 patients, investigated at rest, i.v. injected 37 MBq (99m)Tc-MIBI, scintigraphy performed at 30 min, immediately after that administration of 20 mg Isosorbitdinitrate per os and delayed scintigraphy at 2nd and 4th hour. Myocardial SPECT imaging using Siemens Diacam with semiquantitative analysis of acquisition data was performed.


RESULTS
The results established significant but low tracer redistribution in Gr. I, mean redistribution 17.5% +/- 5.6. After nitrate administration (Gr. II) we detected increased tracer redistribution, mean 30.4% +/- 7.8. The redistribution is higher at the 4th hour, compared to that obtained at 2nd hour after injection. Comparison of the results before and after PTCA showed sensitivity and specificity 93% and 67% respectively.


CONCLUSIONS
It is concluded that after nitrate administration (99m)Tc-MIBI redistribution enhances noticeably and may play a feasible role in detection of viable myocardium in patients with severe CAD.
Tzonevska
A
A
Department of Nuclear Medicine, National Oncology Centre, Sofia, Bulgaria. dr_tzonevska@hotmail.com
Kostadinova
I
I
Tarnovska
R
R
Dimitrova
M
M