Myocardial washout rate of resting 99mTc-Sestamibi (MIBI) uptake to differentiate between normal perfusion and severe three-vessel coronary artery disease documented with invasive coronary angiography

Abstract

Patients with severe coronary artery disease (CAD) may present impaired mitochondrial function to enhance (99m)Tc-sestamibi (MIBI) washout from ischemic myocardium. In this study, we aimed to study the MIBI washout rate (WR) between patients with three-vessel CAD (3V-CAD) confirmed by invasive coronary angiography and healthy normal volunteers (HNV) to evaluate the potential utility of MIBI WR to differentiate between these two populations and to stratify the CAD severity. Ten HNV (male = 5, age = 56 ± 10 years) and eight 3V-CAD patients (male = 4, age = 62 ± 8 years) with 3V lumen stenosis ≥50% were enrolled for this study. Each study subject had a resting MIBI perfusion scan at 90 min and a repeated scan at 4 h post the MIBI injection. Global WR (GWR) and regional WR (RWR) were quantified with the percentage difference of decay-corrected polar maps obtained from the two scans and compared between the HNV and 3V-CAD groups. For the 3V-CAD group, the severity of CAD was assessed with CAD severity scores (CADSS) utilizing degree and location of obstructive lesions (stenosis ≥50%) for quantification and compared with WR to evaluate the correlation between these two variables. Significantly higher GWR was observed in the 3V-CAD (21.1 ± 4.6 %) group than the HNV group (9.5 ± 4.9%) (p < 0.001). RWR values in left anterior descending (LAD), right coronary artery (RCA) and left circumflex (LCX) in the 3V-CAD group were also higher than those of the HNV group (LAD 20.7 ± 5.9 vs 9.4 ± 5.6, p < 0.001; RCA 21.3 ± 4.8 vs 9.2 ± 5.8, p < 0.001; LCX 20.5 ± 7.2 vs 10.1 ± 4.4, p = 0.002). Additionally, the linear correlation of GWR and total CADSS for the whole myocardium was strong and statistically significant (y = 0.86x - 1.12, r (2) = 0.73, p = 0.006). Patients with impaired mitochondrial function due to 3V-CAD had consistently higher global and regional rest (99m)Tc-sestamibi washout rates than those of healthy normal volunteers. The global rest (99m)Tc-sestamibi washout rate is a sensitive indicator to stratify the severity of 3V-CAD and to differentiate between severe 3V-CAD and normal perfusion populations.