Does motion analysis in postexercise gated sestamibi SPECT reflect rest left ventricular motion even in severe coronary artery disease?

Purpose: Evidence has suggested that postexercise gated Tc-99m sestamibi SP ECT (GSPECT) provides combined information about resting wall motion and ex ercise perfusion. No data have been published about possible differences in wall motion analysis between postexercise and resting GSPECT. Methods: Fifty patients underwent postexercise (symptom-limited bicycle str ess) and rest GSPECT and cardiac catheterization with contrast ventriculogr aphy. In 35 patients, additional rest planar Tc-99m RBC radionuclide ventri culography (RNV) was performed. Four observers independently performed left ventricular ejection fraction (LVEF) calculations and visual analysis of r egional wall motion (graded in four stages) for all studies. Results: The LVEF calculations in GSPECT revealed a statistically significa nt difference between postexercise (45.8 +/- 15.7%) and rest (48.0 +/- 16.1 %; P < 0.05) determination. Postrest GSPECT LVEF showed a better correlatio n with LVEF determination performed with contrast ventriculography and RNV than did postexercise GSPECT LVEF. The reduced postexercise wall motion cou ld be shown in segments with exercise-induced ischemia and in those with no rmal regional perfusion but not in segments with irreversibly abnormal perf usion. Conclusions: Postexercise GSPECT provides reliable information regarding gl obal wall motion even in severe coronary artery disease, but regional wall motion is underestimated compared with rest GSPECT, because of an imprecise surface detection algorithm in ischemic wall segments and possibly postexe rcise stunning in severe coronary artery disease.