RT Journal Article
SR Electronic
T1 Is Septal Glucose Metabolism Altered in Patients with Left Bundle Branch Block and Ischemic Cardiomyopathy?
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 1763
OP 1768
VO 47
IS 11
A1 Kerry Thompson
A1 George Saab
A1 David Birnie
A1 Benjamin J.W. Chow
A1 Heikki Ukkonen
A1 Karthik Ananthasubramaniam
A1 Robert A. deKemp
A1 Linda Garrard
A1 Terrence D. Ruddy
A1 Jean N. DaSilva
A1 Rob S.B. Beanlands
YR 2006
UL http://jnm.snmjournals.org/content/47/11/1763.abstract
AB Left bundle branch block (LBBB) is common in patients with heart failure (HF) and contributes to left ventricular (LV) dysfunction. The abnormal septal motion may alter septal metabolic demand but this has not been well characterized in patients with ischemic cardiomyopathy (ICM) and LV dysfunction. The aim of this study was to determine the effect of LBBB on septal metabolism in patients with ICM, LV dysfunction, and LBBB. Methods: Fifty-three patients with LV dysfunction and ICM were identified: 34 with LBBB, 19 with normal QRS (≤100, control patients). PET using 18F-FDG and 82Rb was used to measure myocardial glucose metabolism and perfusion, respectively. Perfusion-metabolism differences were determined. Scar scores (matched decreases in 18F-FDG and 82Rb), mismatch scores (hibernating myocardium with decreased 82Rb relative to 18F-FDG), and reverse-mismatch (R-MM) scores (reduced 18F-FDG relative to 82Rb) were assessed in the septum and lateral wall. Results: 18F-FDG uptake in the septum was reduced in patients with LBBB (64.0% ± 15.4%) compared with control patients (74.9% ± 14.3%; P < 0.05). Mean septal R-MM was greater in patients with LBBB (19.1% ± 15.3%) versus control patients (4.7% ± 10.6%; P < 0.05). However, 32% (11/34) of patients with LBBB did not demonstrate septal R-MM, 91% (10/11) of whom demonstrated lateral wall perfusion defects. Of the 68% (23/34) of patients with LBBB and septal R-MM, 52% (12/23) demonstrated lateral wall perfusion defects (P < 0.05). There was a significant difference in the percentage of the lateral wall with scar between those with septal R-MM (9.3% ± 10.5%) and those without (19.9% ± 14.3%; P < 0.05). Conclusion: Previously, LBBB was believed to be characterized by reduced glucose metabolism relative to perfusion in the septum; however, this is not always the case in ICM. LBBB is not associated with septal R-MM in >30% of this patient population. Absence of this finding was often associated with lateral wall perfusion defects, suggesting an alteration in the metabolic demand on the septum. This may have implications for HF therapies such as resynchronization and requires further study.