Elsevier

Journal of Nuclear Cardiology

Volume 14, Issue 3, May–June 2007, Pages 298-307
Journal of Nuclear Cardiology

Original article
Evaluation of left ventricular mechanical dyssynchrony as determined by phase analysis of ECG-gated SPECT myocardial perfusion imaging in patients with left ventricular dysfunction and conduction disturbances

https://doi.org/10.1016/j.nuclcard.2007.01.041Get rights and content

Background

Cardiac resynchronization therapy (CRT) is approved for the treatment of patients with advanced systolic heart failure and evidence of dyssynchrony on electrocardiograms. However, a significant percentage of patients do not demonstrate improvement with CRT. Echocardiographic techniques have been used for more accurate determination of dyssynchrony. Single photon emission computed tomography (SPECT) myocardial perfusion imaging has not previously been used to evaluate cardiac dyssynchrony. The objective of this study is to evaluate mechanical dyssynchrony as described by phase analysis of gated SPECT images in patients with left ventricular dysfunction, conduction delays, and ventricular paced rhythms.

Methods and Results

A novel count-based method is used to extract regional systolic wall thickening amplitude and phase from gated SPECT images. Five indices describing the phase dispersion of the onset of mechanical contraction are determined: peak phase, phase SD, bandwidth, skewness, and kurtosis. These indices were determined in consecutive patients with left ventricular dysfunction (n = 120), left bundle branch block (n = 33), right bundle branch block (n = 19), and ventricular paced rhythms (n = 23) and were compared with normal control subjects (n = 157). Phase SD, bandwidth, skewness, and kurtosis were significantly different between patients with left ventricular dysfunction, left bundle branch block, right bundle branch block, and ventricular paced rhythms and normal control subjects (all P < .001) Peak phase was significantly different between patients with right ventricular paced rhythms and normal control subjects (P = .001).

Conclusions

A novel SPECT technique for describing left ventricular mechanical dyssynchrony has been developed and may prove useful in the evaluation of patients for CRT.

Section snippets

OMC Determination and Phase Analysis

Each subject enrolled in this study underwent a standard ECG-gated SPECT myocardial perfusion scan for clinical indications at 1 of 3 participating medical centers. Data were acquired at 8 frames per cardiac cycle. The R-R window used for gating was averaged from the prescan electrocardiogram. The short-axis data sets were generated by Butterworth filtering, followed by filtered backprojection reconstruction and oblique reorientation. Three-dimensional count distributions were then extracted

Results

Table 2 shows the 5 quantitative indices describing the left ventricular regional OMC in subjects with left ventricular dysfunction and normal control subjects. Peak phase did not differ significantly between subjects with left ventricular dysfunction and normal control subjects (130.8° ± 28.3° vs 134.8° ± 18.7°, P = .15). However, phase SD (47.8° ± 19.4° vs 15.7° ± 11.8°, P < .001), bandwidth (147.0° ± 70.9° vs 42.0° ± 28.4°, P < .001), skewness (2.7 ± 0.8 vs 4.6 ± 2.4, P < .001), and kurtosis

Discussion

CRT is approved for the treatment of patients with New York Heart Association class III/IV heart failure symptoms who have ejection fractions of 35% or less and a QRS duration of greater than 120 milliseconds on a surface electrocardiogram. Several studies have shown benefits with CRT when added to optimal medical therapy for groups of patients who meet these selection criteria. These benefits include improved functional status, exercise tolerance, quality of life, and left ventricular reverse

Acknowledgment

Dr. Garcia reports an ownership interest in and serves as a consultant/advisor board member to Syntermed Inc. Dr. Garcia also receives royalties from the sale of clinical software that was used as part of this research. Mr. Pagnanelli is a member of the speaker’s bureau for GE Healthcare.

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    This study was funded in part by a research grant from the Medtronic-Duke Strategic Alliance, of which Dr Borges-Neto is the primary investigator.

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