Key result
CMR identifies CRT nonresponders more reliably than SPECT in patients with DCM.
Why the study?
The ability of contrast-enhanced magnetic resonance imaging and SPECT perfusion imaging to detect regional myocardial scars and predict response to cardiac resynchronization therapy has not been fully evaluated.
Does CMR improve the identification of nonresponders to CRT compared to SPECT in patients with cardiomyopathy?
Observational (n=24)
Does CMR improve the identification of nonresponders to CRT compared to SPECT in patients with cardiomyopathy?
CMR is superior to SPECT for identifying nonresponders to CRT in patients with DCM because it avoids the attenuation artifacts that cause SPECT to overestimate scar tissue in the LV inferior wall.
CMR may better identify CRT nonresponders than SPECT in DCM; leaves open whether this refines patient selection or improves outcomes.
BACKGROUND: Left ventricular (LV) postero-lateral scar and total scar burden are factors responsible for a poor response to cardiac resynchronization therapy (CRT). Contrast-enhanced magnetic resonance imaging (CMR) and (99m)Tc-2-methoxy isobutyl isonitrile single photon emission computed tomography (SPECT) perfusion imaging are widely used to detect myocardial scar tissue; however, their ability to detect regional scars and predict a positive response to CRT has not been fully evaluated. METHODS: CMR and SPECT were performed in 17 patients with dilated cardiomyopathy (DCM) and seven patients with ischemic cardiomyopathy (ICM) before CRT. All images were scored, using a 17-segment model. To analyze the LV scar regions by CMR, we assessed the transmural delayed enhancement extent as the transmural score in each segment (0 = no scar, 4 = transmural scar). Similarly, a perfusion defect score was assigned to each segment by SPECT (0 = normal uptake, 4 = defect). RESULTS: By both SPECT and CMR imaging, the total scar score was significantly higher in the ICM than in the DCM group. An LV postero-lateral wall scar region was detected using both imaging modes. By SPECT imaging, the percentage of regional scar score in the LV inferior wall was significantly higher in the DCM than in the ICM group. CONCLUSIONS: By SPECT imaging in the DCM group, severe perfusion defects, due to attenuation artifacts, were frequently observed in the LV inferior wall, resulting in the overestimation of scar tissue. CMR identified nonresponders to CRT more reliably than SPECT in patients with DCM.
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Yokokawa et al. (2009) conducted an observational in Dilated and ischemic cardiomyopathy before cardiac resynchronization therapy (n=24). Contrast-enhanced magnetic resonance imaging (CMR) vs. SPECT perfusion imaging was evaluated on Identification of nonresponders to cardiac resynchronization therapy. Contrast-enhanced magnetic resonance imaging identified nonresponders to cardiac resynchronization therapy more reliably than SPECT in patients with dilated cardiomyopathy.
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