Unique contraction pattern in patients after coronary bypass graft surgery by gated SPECT myocardial perfusion imaging.

Abstract

Although left ventricular systolic function seems to be accurately represented on gated SPECT myocardial perfusion imaging, specific patterns of wall motion (WM) and thickening after coronary bypass graft surgery (CABG), demonstrated by other imaging methods, have not been characterized for gated SPECT myocardial perfusion imaging. Gated SPECT myocardial perfusion imaging was studied in 30 consecutive patients after CABG (group 1) and 40 non-CABG patients-30 with normal stress perfusion studies (group 2) and 10 with known previous anterior wall infarction (group 3). Two expert readers evaluated epicardial and endocardial systolic WM. Regional WM and the thickening percentage were obtained using CEQUAL 20 segment bull's eye analysis and compiled into regional values. Qualitatively, the post-CABG patients had hypokinetic septum, a hyperdynamic lateral wall, and preservation of anterior WM. In 25 of 30 (83.3%) patients, an anterior systolic epicardial "swing" was evident and was different from the inward endocardial and epicardial motion seen in groups 2 and 3. Septal WM was decreased in group 1 compared with group 2 (2.9 vs. 6.0 mm, < 0.001), with no significant difference in septal thickening. This was not different from the reduced septal motion seen in group 3 (4.1 mm), which was accompanied by both reduced thickening and abnormalities of anterior WM. Lateral WM was increased in group 1 compared with group 2 (9.9 vs. 8.2, < 0.001), with no significant difference in lateral wall thickening (34.6% vs. 39%). There is a characteristic contraction pattern on gated SPECT myocardial perfusion imaging in post-CABG patients distinguished by apparent septal hypokinesis with preservation of septal wall thickening, apparent increase in endocardial lateral WM, and an anterior epicardial "swing," different from the contraction pattern seen in normal patients and those with previous anterior wall infarction. The related perfusion pattern aids in evaluation of the mechanism of these findings.