Objective Myocardial perfusion imaging (MPI) may underestimate the extent of disease in patients with multivessel coronary artery disease (CAD), the aim of this study was to investigate the changes of 99mTc-MIBI washout rate (WR) in 3-vessel CAD and its potential application in detection of 3-vessel CAD.
Methods Sixteen patients (ten males, six females; mean age, 62.50 ± 6.95 years) who were clinically diagnosed as IHD with three-vessel stenosis (≥50%) according to coronary angiography (CAG) results, and without myocardial infarction, underwent 99mTc-MIBI static planar and gated single-photon emission computed tomography (SPECT) imaging at 90 minutes and 4 hours, The same imaging was performed on control participants (five males, five females; mean age, 55.70 ± 10.42 years). The global cardiac 99mTc-MIBI WR and regional 99mTc-MIBI WR using a 17-segment model were calculated.
Results Statistically higher global cardiac 99mTc-MIBI WR was observed in the IHD group than the control group [(19.24 ± 4.71) % vs (15.23 ± 3.81) %, p < 0.05]. The myocardial segments of patients were divided into three groups on the basis of the degree of coronary stenosis: group A (n = 138): stenosis from 90% to 100%; group B (n = 68): stenosis from 75% to 89%; group C (n = 66): stenosis from 50% to 74%. Segments of normal participants were defined as group D (n = 170). group A segments showed higher regional 99mTc-MIBI WR (18.21 ± 7.27%, P < 0.05) compared with group B, C, D segments (15.65 ± 6.99%, 15.92 ± 6.82% and 14.49 ± 6.63%, respectively). The number of segments with severe stenosis (group A) was linearly correlated with the mean regional 99mTc-MIBI WR of each patient (r = 0.67, p < 0.01).
Conclusions 99mTc-MIBI WR may reflect myocardium impairment due to ischemia; it may be helpful to discriminate three-vessel stenosis from IHD patients whose myocardial perfusion imaging indicated a normal prognosis.