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Can LV Dyssynchrony as Assessed with Phase Analysis on Gated Myocardial Perfusion SPECT Predict Response to CRT?

¹ Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands; ² Department of Radiology, Emory University School of Medicine, Atlanta, Georgia; ³ Department of Nuclear Medicine, Leiden University Medical Center, Leiden, The Netherlands; and ⁴ The Interuniversity Cardiology Institute of The Netherlands, Utrecht, The Netherlands

View larger version (10K): [in this window] [in a new window]   FIGURE 1.  (A) Changes in LVEDV from baseline (white bars) to 6-mo follow-up (black bars) in responders and nonresponders to CRT. LVEDV decreased significantly in responders and remained unchanged in nonresponders. *P < 0.0001 baseline vs. 6-mo follow-up. (B) Changes in LVESV from baseline (white bars) to 6-mo follow-up (black bars) in responders and nonresponders to CRT. LVESV decreased significantly in responders and remained unchanged in nonresponders. *P < 0.0001 baseline vs. 6-mo follow-up. (C) Changes in LVEF from baseline (white bars) to 6-mo follow-up (black bars) in responders and nonresponders to CRT. LVEF increased significantly in responders and remained unchanged in nonresponders. *P < 0.0001 baseline vs. 6-mo follow-up.

View larger version (68K): [in this window] [in a new window]   FIGURE 2.  (A) Example of phase analysis in a nonresponder to CRT. At baseline, no LV dyssynchrony with phase analysis was present in this patient. Nonnormalized (top panel) and normalized (bottom panel) phase distributions are relatively uniform and the corresponding phase histograms are highly peaked, narrow distributions. After 6-mo follow-up, no response to CRT was observed, as reflected by deterioration in NYHA functional class from 3 to 4. In addition, LVEF remained unchanged (baseline [32%] vs. 6-mo follow-up [33%]). (B) Example of phase analysis in a responder to CRT. In this patient, LV dyssynchrony with phase analysis was present at baseline. Nonnormalized (top panel) and normalized (bottom panel) phase distributions show substantial nonuniformity, whereas the corresponding phase histograms are widely spread distributions. After 6-mo follow-up, this patient improved in NYHA functional class from 3 to 2, indicating response to CRT. In addition, LVEF increased from 27% at baseline to 33% at 6-mo follow-up.

View larger version (9K): [in this window] [in a new window]   FIGURE 3.  ROC analysis of histogram bandwidth demonstrated a sensitivity and specificity of 70% to predict response to CRT at cutoff level of 135° for histogram bandwidth.

View larger version (9K): [in this window] [in a new window]   FIGURE 4.  ROC curve analysis of phase SD demonstrated a sensitivity and specificity of 74% to predict response to CRT at cutoff level of 43° for phase SD.

View larger version (8K): [in this window] [in a new window]   FIGURE 5.  Comparison of difference of phases obtained when 8 frames per cycle (left panel) or 16 frames per cycle (right panel) data acquisition are used. Points in right panel are counts of a pixel arbitrarily chosen from the anterior region of polar maps given by a set of gated (16 frames per cycle) short-axis images. These points are regional maximum counts and their variations represent wall thickness changes at region over the cardiac cycle. Points in left panel are down-sampled from points in right panel. Curves are the first harmonics that approximate wall thickness changes during the cardiac cycle. With first harmonic approximation, phase difference between 8 frames per cycle and 16 frames per cycle is very small at –0.5° (360° corresponds to 1 cardiac cycle).