Detection of residual wall motion after myocardial infarction by gated technetium-99m tetrofosmin SPET: a comparison with contrast ventriculography

The differentiation of residual viability from necrotic myocardium in patie nts with a prior myocardial infarction is important when deciding whether r evascularization is indicated, Myocardial viability can be assessed by stud ying perfusion and regional wall motion. Gated single-photon emission tomog raphy (SPET) imaging allows the simultaneous assessment of perfusion and fu nction through a single study. The aim of this study was to analyse the con cordance between wall motion score derived by gated SPET and by contrast ve ntriculography. Furthermore, the agreement between myocardial perfusion and regional myocardial wall motion was analysed for both techniques. We studi ed a homogeneous group of 26 consecutive patients with a prior myocardial i nfarction, using both gated technetium-99m tetrofosmin SPET and contrast ve ntriculography. A seven-segment model of the left ventricle was employed to score regional myocardial wall motion on images obtained with gated SPET a nd contrast ventriculography using a four-point scale. Contrast ventriculog raphy was performed within 2 weeks of the gated SPET study. Prevalence of a bnormal wall motion (akinetic or dyskinetic) was 24/182 (13%) for gated SPE T and 25/182 (14%) for contrast ventriculography (P=NS). There was a high a gree ment (80%) in wall motion score between gated SPET and contrast ventri culography (kappa =0.67, P<0.001). The agreement was better in segments wit h normal or mild to moderate hypoperfusion (82%, <kappa>=0.69) than in thos e with severe hypoperfusion (67%, kappa =0.56). The agreement between myoca rdial perfusion and myocardial wall motion was 89% (162/182), kappa =0.57, for Sated SPET and 80% (145/182), kappa =0.21, for contrast ventriculograph y. The relation between the summed wall motion scores per patient on gated SPET and contrast ventriculography was excellent (y=0.81x+2.9, r=0.82, P<0. 01). Thirteen (43%) out of 30 segments with severely diminished or no myoca rdial perfusion showed normal or hypokinetic wall motion on gated SPET, sug gesting residual myocardial viability in malperfused regions. Our results s uggest that gated SPET imaging is a reliable tool for the assessment of reg ional wall motion in post-myocardial infarction patients. Furthermore, in p atients with a previous myocardial infarction, gated SPET imaging has the p otential to detect preserved wall motion in regions with fixed perfusion de fects, which might be indicative of residual myocardial viability.