Improved detection of myocardial perfusion reversibility by rest-nitroglycerin Tc-99m-MIBI: Comparison with Tl-201 reinjection

Background. The role of nitroglycerin (NTG) in Tc-99m-methoxyisobutil isoni trile (MIBI) studies to improve the assessment of myocardial viability in p atients with coronary artery disease and its comparison with Tl-201 reinjec tion has not yet been clarified. This study aimed to test whether sublingua l administration of NTG could improve the capability of Tc-99m-MIBI to dete ct reversibility in exercise-induced perfusion defects and to compare it wi th the Tl-201 stress-redistribution-reinjection protocol. Methods and Results. Thirty-eight patients (33 men, 5 women; mean age 49.3 +/- 8.2 years with previous myocardial infarction [mean evolution 7.1 +/- 3 .9 months]) underwent exercise, redistribution, and reinjection Tl-201 imag ing, as well as exercise, rest, and NTG MIBI myocardial scintigraphy (3-day protocol). A total of 494 myocardial segments were assessed by quantitativ e analysis. Of the 136 myocardial segments with fixed defects on exercise-r est sestamibi imaging, 109 (80%) did not change after NTG MIBI study, and 2 7 (20%) demonstrated enhanced uptake, In the 140 myocardial segments with f ixed defects on exercise-redistribution thallium imaging, 112 (80%) did not improve after Tl-201 reinjection study, and 28 (20%) showed increased acti vity. The observed agreement on reversibility detection between NTG MIBI an d Tl-201 reinjection, with the 210 segments with perfusion defects used for this analysis on both studies, was 78%, with a significant kappa = .56 +/- .07 SE. Conclusion. Our data suggest that the use of an NTG MIBI protocol results i n an incremental improvement for detecting exercise-induced perfusion defec t reversibility and achieves results similar to those from a Tl-201 reinjec tion protocol.