Thallium gated SPECT: relation between immediate post-stress evolution of ejection fraction and severity of perfusion pattern

Background and aims A significant decrease of left ventricular ejection fra ction (LVEF) at stress has been reported with Tc-99(m) gated single-photon emission computed tomography (gSPECT) in severe myocardial stunning up to 1 h after exercise. This study was designed to show whether Tl-201 gSPECT ca n measure LVEF evolution from rest to stress in routine examination and giv e additional information to perfusion interpretation since acquisition star ts immediately after stress test. Methods Post-exercise and rest Tl-201 gSPECT were performed in 187 patients with suspected coronary artery disease. Myocardial perfusion was quantifie d by 20-segment analysis. Patients were divided into four groups according to their summed perfusion score, reversibility rate and electrocardiographi c findings, i.e. in order of severity: I = normal perfusion, II = fixed def ect owing to a myocardial infarction, III = full reversible ischaemia, and TV = partial reversible ischaemia. LVEF was calculated by Germane's automat ic algorithm. Results Normal subjects (n=29) and infarcted patients (n=34) showed a signi ficant LVEF increase between rest and stress, +7+/-9% and +5+/-7% respectiv ely. In full reversible ischaemic patients (n=46), stress LVEF showed no in crease (+1+/-8%) and this group was statistically different from both group I and group II. Furthermore, when ischaemia was partially reversible (n=31 ), LVEF decreased significantly (-3+/-8%), particularly when exercise tests were abnormal (-4+/-8%). Group IV was statistically different from groups I and II. Conclusions Good agreement exists between the severity of ischaemic perfusi on pattern and LVEF degradation at stress, which is consistent with previou sly published data using Tc-99(m) gSPECT. Additionally, the use of Tl-201 f or immediate post-exercise imaging allows the observation of a physiologica l LVEF increase in normal and infarcted patients. ((C) 2001 Lippincott Will iams & Wilkins).