title: New insight into scar-related ventricular tachycardia circuits in ischemic cardiomyopathy: Fat deposition after myocardial infarction on computed tomography--A pilot study.
abstract: BACKGROUND
  Myocardial fat deposition (FAT-DEP) has been frequently observed in regions of chronic myocardial infarction in patients with ischemic cardiomyopathy. The role of FAT-DEP within scar-related ventricular tachycardia (VT) circuits has not been investigated.
  
  
  OBJECTIVE
  This pilot study aimed to assess the impact of myocardial FAT-DEP on local electrograms and VT circuits in patients with ischemic cardiomyopathy.
  
  
  METHODS
  Contrast-enhanced computed tomography was performed in 22 patients with ischemic VT. Electroanatomic map points were registered to the corresponding contrast-enhanced computed tomography images. Myocardial FAT-DEP was identified and characterized using a postprocessing image overlay that highlighted areas below 0 Hounsfield units (HU). The mean attenuation of local myocardial regions corresponding to sampled electrograms was measured on short-axis images. The associations of mean attenuation with bipolar and unipolar amplitudes, left ventricular wall thickness, and VT circuit sites were investigated.
  
  
  RESULTS
  Of 1801 electroanatomic map points, 519 (28.8%) were located in regions with FAT-DEP. Significant differences were observed in mean intensity (23.2 ± 35.6 HU vs 81.7 ± 21.9 HU; P < .001), bipolar (0.75 ± 0.83 mV vs 2.9 ± 2.4 mV; P < .001) and unipolar (3.1 ± 1.7 mV vs 7.4 ± 4.3 mV; P < .001) amplitudes, and left ventricular wall thickness (5.2 ± 1.7 mm vs 8.2 ± 2.5 mm; P < .001) between regions with and without FAT-DEP. Lower HU was strongly associated with lower bipolar and unipolar amplitudes (P < .0001, respectively). Importantly, FAT-DEP was associated with critical VT circuit sites with fractionated or isolated potentials.
  
  
  CONCLUSIONS
  FAT-DEP was associated with electrogram characteristics and VT circuit sites. Further work will be needed to determine whether FAT-DEP plays a causal role in the generation of ischemic scar-related VT circuits.
authors: Departments of *Cardiology. Electronic address: tsasaki.cvm@tmd.ac.jp.
authors: Takeshi
authors: T
authors: Sasaki
authors: Departments of *Cardiology.
authors: Hugh
authors: H
authors: Calkins
authors: Departments of *Cardiology.
authors: Christopher F
authors: CF
authors: Miller
authors: Departments of *Cardiology.
authors: Menekhem M
authors: MM
authors: Zviman
authors: Biostatistics, Johns Hopkins University, Baltimore, Maryland.
authors: Vadim
authors: V
authors: Zipunnikov
authors: Department of Pathology, Tokyo Metropolitan Geriatric Hospital, Tokyo, Japan.
authors: Tomio
authors: T
authors: Arai
authors: Department of Molecular Pathology, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Motoji
authors: M
authors: Sawabe
authors: Cardiovascular Imaging Clinic Iidabashi, Tokyo, Japan.
authors: Masashiro
authors: M
authors: Terashima
authors: Departments of *Cardiology.
authors: Joseph E
authors: JE
authors: Marine
authors: Departments of *Cardiology.
authors: Ronald D
authors: RD
authors: Berger
authors: Departments of *Cardiology.
authors: Saman
authors: S
authors: Nazarian
authors: Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, Maryland.
authors: Stefan L
authors: SL
authors: Zimmerman
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging*; D000368:Aged; D018780:Body Surface Potential Mapping / Q000379:methods; D009202:Cardiomyopathies / Q000150:complications / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D002921:Cicatrix / Q000209:etiology / Q000473:pathology; D003287:Contrast Media / Q000494:pharmacology; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications*; D009206:Myocardium / Q000473:pathology*; D011856:Radiographic Image Enhancement; D015203:Reproducibility of Results; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D003287:Contrast Media
keywords: Computed tomography; Fat; Ischemic cardiomyopathy; Magnetic resonance imaging; Ventricular tachycardia