Post-stress end-systolic left ventricular dilation: a marker of endocardial post-ischemic stunning

Abstract

Several studies have shown the accuracy of gated single photon emission computed tomography (SPECT) using thallium-201 and technetium tracers in the assessment of myocardial perfusion and function. Gated SPECT has been successfully utilized to detect post-stress left ventricular ejection fraction (LVEF) reduction resulting from post-ischemic stunning in patients with coronary obstruction. The aim of this study was to evaluate whether the post-stress LVEF impairment could be related to the post-stress end-systolic ventricular dilation resulting from post-ischemic endocardial stunning. Two hundred and eighty-two consecutive patients were studied by conventional diagnostic 2 day stress/rest gated SPECT following injection of 925 MBq of 99mTc-tetrofosmin using a dual-headed SPECT camera. One hundred and forty-seven of these patients (52%) showed reversible perfusion defects, 69 (24%) permanent defects and the remaining 66 (24%) had normal perfusion. One hundred and thirty-eight of these patients had a history of myocardial infarction (MI) and 19% underwent coronary angiography without an intervening cardiac event. Perfusion was analysed on ungated images using 20 segments scored on a five-point scale (0, normal; 4, no uptake), while wall thickening (WT) was assessed visually on stress/rest end-systolic images using a four-point score (0, normal; 3, absence of WT). LVEF and volumes were calculated using an automatic algorithm. The post-stress and rest ratios were determined for both end-diastolic (EDV) and end-systolic (ESV) volume. Normal values for all these parameters were obtained using data from 149 patients with a low likelihood (<5%) of coronary artery disease (CAD). In 50 of the 147 (34%) of patients with reversible perfusion defects, post-stress LVEF was >5% lower than rest values (stunned group), while the remaining 97 patients did not show a significant LVEF change (group 2A). The percentage of patients who developed exercise-induced angina, the percentage of patients who underwent coronary angiography and the segmental summed perfusion and WT scores were significantly higher in the stunned group compared with group 2A. Only ESV increased significantly post-stress, and this increase occurred only in stunned patients. Both EDV and ESV ratios were significantly higher in the stunned group compared with normal controls (P=0.008 and P<0.000001, respectively) and with the subgroup 2A (P=0.011 and P<10(-12), respectively). The ESV stress/rest ratio correlated significantly with the summed WT difference score by univariate analysis in stunned patients. It can be concluded that the post-stress ESV dilation, obtained by stress/rest gated SPECT, seems to be due to endocardial post-ischemic stunning. The stunned patients showed more severe clinical, angiographic, perfusion and function parameters.

Influence of the postexercise acquisition delay on the detection of functional abnormalities in sestamibi-gated SPECT

“…[1][2][3] In the studies about poststress gated SPECT functional changes, the time interval between tracer injection and poststress imaging ranged from 15 minutes to more than 60 minutes, and there was no direct comparison between different delays. 1,2,[19][20][21][22][23][24][25][26][27][28] Recently, Toba et al 3 reported that in patients with single-vessel CAD, a very early (10 minutes) poststress gated SPECT study was superior to the usual 30-and 50-minute intervals to identify transient decreases in EF in the subjects with stress-induced ischemia, and they confirmed the relationship between severity of ischemia and degree of functional impairment. To our knowledge, their study is the only one addressing the issue of ischemiarelated functional changes by comparing different acquisition delays.…”

Do we really need to look at volumetric measurements with 99mTc single photon emission computed tomography (SPECT) myocardial perfusion imaging?

“…11,12 Others explain it by a stress-induced subendocardial hypoperfusion giving the visual impression of dilatation on ungated SPECT. 13,14 Nonetheless, the severity of post-ischemic stunning differs between the different stress agents: it seems that myocardial dysfunction persists much longer after dobutamine than after See related article, https://doi …”

“…11,12 Others explain it by a stress-induced subendocardial hypoperfusion giving the visual impression of dilatation on ungated SPECT. 13,14 Nonetheless, the severity of post-ischemic stunning differs between the different stress agents: it seems that myocardial dysfunction persists much longer after dobutamine than after adenosine stress. 12,15,16 All these challenges may affect the accurate and reliable estimation of myocardial stunning and could result not only in high inter-and intra-patient variability but also between different SPECT scanners and image acquisition protocols.…”

Transient ischemic dilation: An old but not obsolete marker of extensive coronary artery disease

“…5,6 According to this explanation, post-stress stunning results in end-systolic volume enlargement of the left ventricle. Since non-gated images used for TID calculation reflect summation of counts originating from the whole cardiac cycle, reduced post-stress ventricular contraction with larger end-systolic volume results in increased non-gated LV volume and increased TID ratio.…”

“…Since non-gated images used for TID calculation reflect summation of counts originating from the whole cardiac cycle, reduced post-stress ventricular contraction with larger end-systolic volume results in increased non-gated LV volume and increased TID ratio. Betesti et al 5 demonstrated that post-stress LV dilation by gated SPECT reflected endocardial post-ischemic stunning with reduced ejection fraction and thickening score, and was associated with more severe clinical, angiographic, and perfusion parameters. Another investigation supporting this mechanism demonstrated LV dysfunction at stress echocardiography among patients with TID at MPI.…”