Assessment of hibernating myocardium with Tc-99m sestamibi Spect: Effect of nitroglycerine and trimetazidine administration.

Abstract

Myocardial perfusion imaging with ThaIIum-2O1 has been established as non-invasive method for assessment of myocardial viability in-patients7 with ischaemic left ventricular dysfunction. Technetium agents, owing to their better imaging characteristics and case of availability, are now increasingly used for this purpose. Results with Tc- 99m Sestamibi are quite encouraging and show good agreement with those of thallium-201 imaging. Use of nitrates in conjunction with Tc-99m Sestamibi has been shown to enhance the sensitivity for detection myocardial viability. This study was designed to observe the effect of a new agent, trimetazidine, on the diagnostic yield of Tc-99m Sestamibi myocardial perfusion SPECT in comparison with baseline and post nitroglycerine studies. 25 patients (19 males, 6 females) aged 46±3.9 years with established coronary artery disease and left ventricular dysfunction were included in the study. All patients underwent a baseline study, a post nitroglycerine study and a post trimetazidine study on three separate days using the same dose of Tc-99m Sestamibi and imaging protocol. The data were reconstructed in trans axial slices and then reoriented into short, vertical long and horizontal slices. The images were split into 20-segment model and were qualitatively and quantitatively analyzed by three independent observers. Each segment was assigned a score ranging from O to 4 depending upon its perfusion status. Segments having score 1 were considered non-viable while segment with score 2 were considered viable. In the baseline study, 69.6% (348/500) segments were viable. This number increased to 74.4% (372/500) in post nitroglycerine study and to 74.2% (371/500) in post trimetazidine study. Concordance was observed in 94% segments in nitroglycerine and trimetazidine studies. Quantitative scores improved significantly in post nitroglycerine and Post trimetazidine studies compared with those of baseline study (p < 0.001). Both nitroglycerine as well as trimetazidine administration improve the diagnostic yield of Tc-99m Sestamibi SPECT for assessment of myocardial viability.