Gated single-photon emission tomography imaging protocol to evaluate myocardial stunning after exercise

This study was designed to apply ECG-gating to stress myocardial perfusion single-photon emission tomography (SPET) for the evaluation of myocardial s tunning after exercise. Technetium-99m sestamibi was selected as the perfus ion agent and a rest/exercise 1-day protocol was employed. Fourteen patient s without coronary stenosis and 33 patients with coronary stenosis were enr olled in the study. We carried out three data acquisitions with ECG-gating: a 15-min data acquisition starting 30 min after the rest injection (AC1), a 5-min acquisition starting 5 min after the stress injection (AC2) and a 1 5-min acquisition starting 20 min after the stress injection (AC3). Calcula tion of left ventricular ejection fraction (LVEF) values was performed by m eans of automatic determination of the endocardial surface for all gating i ntervals in the cardiac cycle. Measured global EF values in 14 patients wit hout coronary stenosis were 52.3%+/-7.6% (AC1), 60.6+/-8.9% (AC2) and 55.6% +/-5.6% (AC3), and those in 11 patients with severe ischaemia were 53.6%+/- 8.0% (AC1), 45.6%+/-12.1% (AC2) and 49.7%+/-10.7%. The magnitude of the dep ression of post-stress LVEF relative to the rest LVEF correlated with the s everity of ischaemia (r=0.594, P=0.002), and segments manifesting post-stre ss functional depression were associated with ischaemic segments showing re versible perfusion defects. Stress myocardial perfusion SPET with ECG-gatin g is a feasible method for the evaluation of myocardial stunning as well as exercise-induced ischaemia.