Abstract 18685: Global Myocardial Blood Flow Measurements Correlate with Angiographic Severity of Coronary Artery Disease

Abstract

Background. The correct identification of multivessel coronary artery disease (CAD) is a potential limitation of routine stress-rest using positron emission tomography (PET) myocardial perfusion imaging .We examined whether PET-based myocardial blood flow (MBF) and flow reserve (MFR) can be used to enhance the identification of extensive CAD.

Methods. We identified 115 consecutive patients (pts; 65±11 yrs, 75% men) who underwent Regadenoson stress ⁸²Rb PET and coronary angiography within 6 months. MBF during hyperemia and rest and their ratio (MFR) were quantified. PET metrics included summed rest, stress and difference scores (SRS, SSS and SDS, respectively), transient ischemic dilatation (TID) and changes in ejection fraction (ΔEF). PET results were stratified based on angiographic severity grade from 0 (no stenosis>70% or left main>50%) to 5 (significant 3 vessel and left main CAD) and were analyzed using one way analysis of variance.

Results. In total, 26 pts had no significant CAD (severity score=0); 27, 30, 22 and 10 patients had severity scores of 1, 2, 3 and 4, respectively. Resting global MBF did not vary as a function of CAD severity (ANOVA F-statistic = 1.63, p = 0.17), where as there was a strong correlation between CAD severity and global MBF during stress (F=13.5, p<0.0001, figure), SSS (F=12.8, P<0.0001) and global MFR (F=10.8, p<0.0001). Weaker correlations were observed between coronary severity and SDS, Delta EF, and TID, respectively (F=8.2, 3.1, and 0.6). In the 35 pts (30% of total) with left main stenosis or 3-vessel CAD, 31 (89%) pts had abnormal stress MBF and MFR (using cut-offs of 1.80 ml/min/g and ratio of 2.0, respectively); whereas 54% had negative [[Unable to Display Character: ▵]]EF and only 20% had abnormal TID.

Conclusion. Absolute stress MBF and MFR enhance the diagnostic accuracy of cardiac PET over conventional parameters for the identification of high-risk, severe and extensive CAD. This approach may reduce the incidence of CAD underestimation by PET.