Technetium-99m sestamibi imaging to predict left ventricular ejection fraction outcome after revascularisation in patients with chronic coronary artery disease and left ventricular dysfunction: comparison between baseline and nitrate-enhanced imaging

Acceptance of technetium-99m sestamibi as a tracer of myocardial viability is growing, particularly when nitrate-enhanced imaging is used. However, fe w data are available on the ability of Tc-99m-sestamibi to predict the evol ution of global left ventricular ejection fraction (EF). The aim of this st udy was to examine the ability of resting and nitrate Tc-99m-sestamibi sing le-photon emission tomography (SPET) to predict EF changes after revascular isation in patients who have chronic coronary artery disease with left vent ricular dysfunction. Using baseline resting and nitrate Tc-99m-sestamibi SP ET, we studied 61 patients scheduled for revascularisation because of left ventricular dysfunction. EF was estimated using two-dimensional echocardiog raphy before and after the intervention. A post-revascularisation improveme nt of greater than or equal to5 EF units was defined as significant. Using a 13-segment model, Tc-99m-sestamibi activity was quantified and the nitrat e-induced activity changes calculated. Three different criteria for detecti ng viability (defined as post-revascularisation reversible dysfunction) in asynergic segments were compared: (I) resting Tc-99m-sestamibi activity gre ater than or equal to 60%; (2) nitrate Tc-99m-sestamibi activity greater th an or equal to 65%; and (3) nitrate-induced increase > +10% or nitrate-indu ced increase less than or equal to +10% and nitrate activity greater than o r equal to 65%. EF increased significantly in 32 patients. The number of vi able asynergic segments was significantly higher in these patients than in the remaining 29 subjects, and the difference was greater (P <0.0002) using definition (3) than using either baseline (P <0.002) or nitrate activity ( P <0.0005), There was a significant relationship between EF changes and num ber of viable asynergic segments: Spearman R=0.38, P <0.005 using baseline; Spearman R=0.39, P <0.002 using nitrate activity; and Spearman R=0.55, P < 0.000005 using definition (3). According to receiver operating characterist ic (ROC) curve analysis, this last criterion achieved the best results (81% sensitivity, 69% specificity and 75% accuracy), with an area under the ROC curve of 0.838; this area was significantly larger than when using either baseline (0.744, P <0.02) or nitrate activity (0.747, P <0.005), Tc-99m-ses tamibi SPET appears able to predict the evolution of global left ventricul ar EF after revascularisation, thereby confirming the value of Tc-99m-sesta mibi as a tracer of myocardial viability. The combination of baseline resti ng and nitrate imaging seems to significantly improve the diagnostic accura cy of Tc-99m-sestamibi SPET for this particular purpose.