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 isonitrile (MIBI) studies to improve the assessment of myocardial viability in patients with coronary artery disease and its comparison with Tl-201 reinjection has not yet been clarified. This study aimed to test whether sublingual administration of NTG could improve the capability of Tc-99m-MIBI to detect reversibility in exercise-induced perfusion defects and to compare it with 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 imaging, as well as exercise, rest, and NTG MIBI myocardial scintigraphy (3-day protocol). A total of 494 myocardial segments were assessed by quantitative analysis. Of the 136 myocardial segments with fixed defects on exercise-rest sestamibi imaging, 109 (80%) did not change after NTG MIBI study, and 27 (20%) demonstrated enhanced uptake. In the 140 myocardial segments with fixed defects on exercise-redistribution thallium imaging, 112 (80%) did not improve after Tl-201 reinjection study, and 28 (20%) showed increased activity. The observed agreement on reversibility detection between NTG MIBI and 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 in an incremental improvement for detecting exercise-induced perfusion defect reversibility and achieves results similar to those from a Tl-201 reinjection protocol.