Overestimation of postischemic myocardial stunning on gated SPECT imaging: correlation with echocardiography.
BACKGROUND
Postischemic global and regional left ventricular (LV) dysfunction on stress-gated single photon emission computed tomography (SPECT) imaging is attributed widely to myocardial stunning. We sought to determine the specificity of gated SPECT for the detection of myocardial stunning after ischemic stress.


RESULTS
Twenty-seven patients with an ischemic response to stress on dual-isotope exercise SPECT were enrolled prospectively. Transthoracic echocardiography was performed just before stress gated SPECT for assessment of regional wall motion and quantitative LV ejection fraction (LVEF). The 17 myocardial segments for each patient were scored for myocardial perfusion by stress gated SPECT, and regional wall motion by stress gated SPECT and echo. Of the 459 myocardial segments, 41% had perfusion defects, 15% had stress gated SPECT regional wall motion abnormality, 4.8% had poststress echo regional wall motion abnormality, and 3.9% had baseline regional wall motion abnormality. Overall, a stress gated SPECT regional wall motion abnormality had a sensitivity of 100% and a specificity of 89%. Among reversible perfusion defects of moderate severity or more, a stress gated SPECT regional wall motion abnormality had a specificity of 41% and a positive predictive value of 8%. Stress gated SPECT LVEF was similar to poststress echo LVEF for all patients, but significantly lower in patients with reversible perfusion defects of moderate severity or more.


CONCLUSIONS
Post-stress gated SPECT imaging overestimates global and regional myocardial stunning. Caution should be exercised in interpreting poststress global or regional LV function on stress gated SPECT in scans with reversible ischemia.
Ward
R Parker
RP
Section of Cardiology, Department of Medicine, University of Chicago, Chicago, Ill., USA. pward@medicine.bsd.uchicago.edu
Gundeck
Ethan L
EL
Lang
Roberto M
RM
Spencer
Kirk T
KT
Williams
Kim A
KA
D004452:Echocardiography; D005080:Exercise Test; D005189:False Positive Reactions; D015637:Gated Blood-Pool Imaging / Q000379:methods*; D006801:Humans; D017202:Myocardial Ischemia / Q000150:complications / Q000000981:diagnostic imaging*; D017682:Myocardial Stunning / Q000000981:diagnostic imaging* / Q000209:etiology; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D013223:Statistics as Topic; D013318:Stroke Volume; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000209:etiology