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

Several studies have shown the accuracy of gated single photon emission com puted tomography (SPECT) using thallium-201 and technetium tracers in the a ssessment of myocardial perfusion and function. Gated SPECT has been succes sfully utilized to detect post-stress left ventricular ejection fraction (L VEF) reduction resulting from post-ischemic stunning in patients with coron ary obstruction. The aim of this study was to evaluate whether the post-str ess LVEF impairment could be related to the post-stress end-systolic ventri cular dilation resulting from post-ischemic endocardial stunning. Two hundr ed and eighty-two consecutive patients were studied by conventional diagnos tic 2 day stress/rest gated SPECT following injection of 925 MBq of Tc-99m- tetrofosmin using a dual-headed SPECT camera. One hundred and forty-seven o f these patients (52%) showed reversible perfusion defects, 69 (24%) perman ent defects and the remaining 66 (24%) had normal perfusion. One hundred an d thirty-eight of these patients had a history of myocardial infarction (MI ) and 19% underwent coronary angiography without an intervening cardiac eve nt. 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 sco re (0, normal; 3, absence of WT). LVEF and volumes were calculated using an automatic algorithm. The post-stress and rest ratios were determined for b oth end-diastolic (EDV) and end-systolic (ESV) volume. Normal values for al l these parameters were obtained using data from 149 patients with a low li kelihood (<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 s how a significant LVEF change (group 2A). The percentage of patients who de veloped exercise-induced angina, the percentage of patients who underwent c oronary angiography and the segmental summed perfusion and WT scores were s ignificantly higher in the stunned group compared with group 2A. Only ESV i ncreased significantly post-stress, and this increase occurred only in stun ned patients. Both EDV and ESV ratios were significantly higher in the stun ned group compared with normal controls (P=0.008 and P<0.000001, respective ly) 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 s core by univariate analysis in stunned patients. It can be concluded that t he post-stress ESV dilation, obtained by stress/rest gated SPECT, seems to be due to endocardial post-ischemic stunning. The stunned patients showed m ore severe clinical, angiographic, perfusion and function parameters. ((C) 2001 Lippincott Williams & Wilkins).