Abstract 13144: Impact of Ischemia on Left Ventricular Dyssynchrony by Phase Analysis of Gated Single Photon Emission Computed Tomography Myocardial Perfusion Imaging
Background: There is increasing awareness of the value of phase analysis of gated tomographic myocardial perfusion imaging (MPI) in assessing left ventricular (LV) dyssynchrony. A concern repeatedly raised in many studies is whether reversible defects in the stress images “ischemia” could affect the phase-derived standard deviation and bandwidth, the 2 commonly used dyssynchrony indices. We hypothesized that the stress and rest images should provide comparable information because the images are acquired 1 hour after the tracer injection.
Methods and Results: We studied 2 groups of patients with normal LV ejection fraction and no fixed perfusion defects. In group- 1 (n=20), the patients had reversible perfusion defects involving > 10% of the LV myocardium and in group- 2 (n=20), the patients had normal images. All patients underwent stress/rest gated SPECT sestamibi imaging (the stress study was acquired with the lower dose) between January and March 2010. Patients with left bundle branch block or ventricular pacing were excluded. The patients in group-1 had a mean age of 61 ± 9 years, 65% were men, 75% Caucasians and 70% had known prior coronary artery disease. The size of the reversible perfusion defect was 20 ± 13% (range 11–50%) of the LV myocardium. The rest and stress phase-derived standard deviation (16 ± 6° vs. 18 ± 8° and 16 ± 7° vs. 19 ± 6°) and the rest and stress bandwidth (42 ± 14° vs. 46 ± 16° and 45±17° vs. 52±12°, respectively, (P = NS for all) were similar in the 2 groups. The change (stress-rest) in standard deviation and bandwidth in group 1 and 2 were not statistically significant (0.2 ± 3.1o vs. 1.4 ± 4.7o, and 2 ± 13o vs. 5 ± 13o, respectively, P = NS). There was no significant change from rest to stress in the standard deviation and the bandwidth in group- 1 (P = 0.8 and 0.4, respectively) and group- 2 (P= 0.2 and 0.08, respectively). There was no correlation between the size of the reversible perfusion defect and the change in phase standard deviation or bandwidth (r = 0.07 and 0.12, respectively, P = NS).
Conclusions: The presence of even a large reversible perfusion defect does not alter the indices of mechanical dyssynchrony by phase analysis. Further, comparable information is obtained whether using a low dose or a high dose of the radiotracer
- © 2010 by American Heart Association, Inc.