Comparison of regional myocardial blood flow and perfusion in dilated cardiomyopathy and left bundle branch block: role of wall thickening.
Heterogeneous perfusion in left bundle branch block (LBBB) has been demonstrated by (99m)Tc-methoxyisobutylisonitrile (MIBI) SPECT. Locally different contraction is also associated with LBBB. Quantitative analysis of myocardial SPECT is influenced by partial-volume effects depending on systolic wall thickening. Therefore, partial-volume effects may mimic perfusion heterogeneity in LBBB.


METHODS
Fifteen patients with nonischemic dilated cardiomyopathy and LBBB underwent resting (15)O-water PET, (99m)Tc-MIBI SPECT, and gated (18)F-FDG PET for analysis of wall thickening. Myocardial blood flow corrected for rate-pressure product (corrMBF), (99m)Tc-MIBI uptake, and wall thickening were determined in 4 left ventricular wall areas. In 14 patients, M-mode echocardiographic recordings were available for comparison.


RESULTS
Homogeneous distribution was found for corrMBF (1.09 +/- 0.41 to 1.19 +/- 0.31 mL x g(-1) x min(-1)). (99m)Tc-MIBI uptake and wall thickening were heterogeneous (P < 0.0001), with the lowest values septal ((99m)Tc-MIBI, 65% +/- 10%; wall thickening, 16% +/- 14%) and the highest lateral ((99m)Tc-MIBI, 84% +/- 5%; wall thickening, 55% +/- 17%). Similar relationships in systolic wall thickening were observed by M-mode echocardiography (anteroseptal, 20% +/- 11%; posterolateral, 37% +/- 18%; P < 0.001).


CONCLUSIONS
Heterogeneity of (99m)Tc-MIBI uptake in LBBB corresponds to differences in wall thickening and does not reflect distribution of corrMBF. Supplementary analysis of wall thickening is recommended when assessing (99m)Tc-MIBI SPECT in LBBB.
Nowak
Bernd
B
Department of Nuclear Medicine, University Hospital, Aachen University of Technology, Aachen, Germany. bnowak@ukaachen.de
Stellbrink
Christoph
C
Schaefer
Wolfgang M
WM
Sinha
Anil M
AM
Breithardt
Ole A
OA
Kaiser
Hans-Juergen
HJ
Reinartz
Patrick
P
Hanrath
Peter
P
Buell
Ulrich
U
D000328:Adult; D000368:Aged; D001158:Arteries; D001783:Blood Flow Velocity; D002037:Bundle-Branch Block / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D002311:Cardiomyopathy, Dilated / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D003326:Coronary Circulation; D003331:Coronary Vessels / Q000000981:diagnostic imaging*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010104:Oxygen Radioisotopes; D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods; D014463:Ultrasonography; D018487:Ventricular Dysfunction, Left / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D014867:Water
D010104:Oxygen Radioisotopes; D019275:Radiopharmaceuticals; D014867:Water; D019788:Fluorodeoxyglucose F18; D017256:Technetium Tc 99m Sestamibi