Metabolic mismatch of septal beta-oxidation and glucose utilization in left bundle branch block assessed with PET

Preserved septal uptake of the new long-chain fatty acid analog [18F]FTHA was found in a patient with three-vessel disease, a history of previous anterior myocardial infarction and left bundle branch block (LBBB), despite severely decreased septal [18F]FDG uptake that suggested scarred tissue. Nearly absent [19F]FDG uptake in the septum could not be explained by concordant reduction of septal perfusion as assessed by 99mTc-MIBI SPECT. These data may point to divergent metabolic effects of the conduction abnormality in LBBB with consecutively reduced septal exogenous glucose utilization but unaffected septal beta-oxidation.