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Published on: February 16, 2016
Assessment of the effect of revascularization early after CABG using ECG-gated perfusion single-photon emission
1Department of Nuclear Medicine and Diagnostic Imaging, Kyoto University Graduate School of Medicine, Japan. kub@kuhp.kyoto-u.ac.jp
Insights
Electrocardiography (ECG)-gated single-photon emission tomography (SPET) can help assess coronary artery bypass graft (CABG) surgery outcomes. The transient ischemic dilatation ratio, not perfusion imaging or LVEF, may be a useful early marker of revascularization success.
Area of Science:
- Cardiovascular Imaging
- Nuclear Cardiology
- Cardiac Surgery
Background:
- Reversible perfusion defects are sometimes seen on single-photon emission tomography (SPET) early after coronary artery bypass graft (CABG) surgery, potentially due to restricted arterial graft flow.
- Evaluating the effectiveness of revascularization early after CABG is crucial for patient management and outcomes.
Purpose of the Study:
- To determine if functional information from electrocardiography (ECG)-gated perfusion SPET can effectively evaluate revascularization early after CABG.
- To assess the utility of left ventricular ejection fraction (LVEF) and transient ischemic dilatation (TID) ratio in early post-CABG assessment.
Main Methods:
- Twenty-three patients underwent stress/re-injection thallium-201 ECG-gated SPET before and 4 weeks after CABG.
- Coronary angiography confirmed graft patency one month post-CABG.
- Analysis included LVEF and TID ratio using automated software, alongside conventional SPET interpretation.
Main Results:
- Patent arterial grafts showed reversible perfusion defects in 64% of myocardial segments, compared to 42% for venous grafts (P=0.005).
- The TID ratio significantly improved post-CABG in all patients (P=0.001 and P=0.002).
- LVEF did not significantly improve post-CABG, and perfusion imaging or LVEF assessment showed limited value.
Conclusions:
- Standard perfusion imaging and LVEF assessment have limited value in evaluating early outcomes after CABG.
- The TID ratio derived from ECG-gated perfusion SPET may serve as a valuable early marker for assessing revascularization effectiveness post-CABG.
Abstract:
When an arterial graft is used, reversible perfusion defects on single-photon emission tomography (SPET) perfusion images are occasionally observed early after coronary artery bypass graft surgery (CABG), owing to the restricted flow capacity. The purpose of this study was to determine whether the functional information obtained with electrocardiography (ECG)-gated perfusion SPET could be helpful in evaluating the effect of revascularization early after CABG. Twenty-three patients (18 men and 5 women, mean age 65+/-9 years) underwent stress/re-injection thallium-201 ECG-gated SPET before and 4 weeks after CABG (13 with exercise and 10 with dipyridamole). Patency of all grafts was confirmed by coronary angiography 1 month after CABG. Cardiac functional data including the left ventricular ejection fraction (LVEF) and the transient ischaemic dilatation (TID) ratio were analysed using a commercially available automated program. The conventional stress and re-injection tomograms were interpreted by means of a five-point scoring system in a nine-segment model. Stress-induced reversible 201Tl perfusion defects were present in 64% of the myocardial segments bypassed by patent arterial grafts, in contrast to 42% of the myocardial segments bypassed by patent venous grafts (chi2=7.8, P=0.005). Of the 23 patients, 12 showed improvement in summed ischaemic scores (group 1), while 11 had no change or deterioration (group 2), although all grafts were patent on postoperative catheterization. The TID ratio improved in both group 1 and group 2 before and after CABG (1.14+/-0.13 vs 0.99+/-0.07, P=0.001 and 1.09+/-0.07 vs 0.94+/-0.05, P=0.002, respectively). However, LVEF did not significantly improve in group 1 or group 2 after CABG (42.5%+/-9.9% vs 47.5%+/-11.8%, and 52.1%+/-7.5% vs 53.1%+/-5.9%, respectively). Perfusion imaging or LVEF assessment is of limited value early after CABG. The TID ratio obtained with ECG-gated perfusion SPET may be a useful marker to evaluate the effect of revascularization early after surgery.
