Comparison of nitrate augmented ^99mTc-Sestamibi infusion with nitrate augmented ^99mTc-Sestamibi bolus injection for the detection of myocardial viability

It has been stated that nitrate augmented ^99mTc-Sestamibi bolus injection is almost comparable to 24hour reinjection of Tl-201 for the detection of myocardial viability. This study was aimed to see if nitrateaugmented infusion injection of ^99mTc-Sestamibi can reveal more areas of viable myocardium as compared to the standard stress rest protocol of ^99mTc-Sestamibi and nitrate-augmentation.

25 patients (all men) with a mean age of 42.72 yrs (age ranging from 28–57 yrs) with a recent history of myocardial infarction (3 weeks to 6 months) were included in the study. A routine stress – rest myocardial perfusion scan with ^99mTc-Sestamibi was performed on these subjects. The rest study was augmented with 10 mg of nitroglycerin sublingually. These subjects were given the same dose of nitroglycerin and ^99mTc-Sestamibi two days later. ^99mTc-Sestamibi was given as an infusion over a period of 45 minutes and images were obtained after one hour. 17 segment myocardial model was taken for analysis and a total of 425 segments were analyzed out of which 176 segments were for viability evaluation. Results: In resting images obtained with MIBI bolus injection, there was improvement in 17 segments (9.6%) when compared to the post stress images and in images obtained after infusion, there was improvement in 34 assessed for viability segments (19.3%). In the remaining segments, there was improvement in 48 segments (19.27%) in the images obtained with MIBI bolus injection and improvement in 85 segments (34.13%) in the images obtained with MIBI infusion.

This study shows that nitrate augmented MIBI infusion is helpful in detecting more areas of viable myocardium when compared to the standard resting study following bolus injection.