Abstract 15639: Relationship between Left Ventricular Asynchrony and Coronary Blood Flow Using 82Rb Cardiac Positron Tomography
Objectives: Measurement of left ventricular phase (LVP; time to peak systole/RR interval), is derived from rest gated myocardial perfusion imaging (MPI), and used to quantify synchronicity of LV contraction. Increasing LVP indicates worsening asynchrony. MPI studies with PET/CT 82Rb (PET) obtain perfusion data directly during pharmacologic stress, enabling calculation of stress-induced changes in LVP, and myocardial blood flow (MBF). In this study, we determine the relationships between rest/stress changes in LVP, MBF, and conventional perfusion analysis.
Methods: 45 subjects (29 men, 16 women, age 68±11years) had vasodilator stress, CT attenuation-corrected, PET MPI to evaluate known/suspsected CAD. Global and regional and LVP were calculated from automated algorithms (Emory U, Atlanta, GA) separating RV/LV blood pools and LV myocardial volumes using factor analysis. LVP was calculated for the 17 standard AHA LV segments, which were then also grouped into coronary territories. Z-score, an index of global synchrony, combining all LV segments, was determined for each pt., and compared to our previously established normal range. Summed stress scores (SSS) from Emory Cardiac Toolbox, quantified perfusion defects. Linear regression assessed correlations among variables.
Results: Abnormal Z scores (>2.0) were seen in 16/45 (36%) of pts at rest, and 17/45 (38%) with stress. Z-scores correlated with SSS and global MBF during stress (r= 0.63 and -0.62) and at rest (r=0.61 and -0.58) (p<0.0001). Average LVP in individual coronary territories was 0.28 +0.06, median 0.29. Increasing LVP standard deviation (SD) within specific coronary territories correlated with reduced MBF in the LAD, LCX and RCA territories during stress (r=-0.68, -0.55 and -0.56) and at rest (r=-0.51, -0.47 and -0.50) (p<0.0001). LVP SD also correlated with SSS for the LAD (r=0.81, p<0.0001), LCX (r=0.36, p=0.02), and RCA (r=0.62, p<0.0001). MBF and coronary flow reserve (CFR; MBF-stress/MBF-rest) in coronary territories with LVP>median was lower than for territories <median (73±30 ml/mg versus 89±26 ml/mg, p=0.002; CFR 2.03±0.75 versus 2.45±1.00, p=0.006).
Conclusion: There is a significant correlation between indices of global/regional LV synchronicity and MBF and CFR.
- © 2010 by American Heart Association, Inc.