title: Hibernating substrate of ventricular tachycardia: a three-dimensional metabolic and electro-anatomic assessment.
abstract: OBJECTIVE
  Hibernating myocardium (HM) is associated with sudden cardiac death (SCD). Little is known about the electrophysiological properties of HM and the basis of its association with SCD. We aimed to electrophysiologically characterize HM in patients with ventricular tachycardia (VT).
  
  
  METHODS
  Endocardial voltage mapping, metabolic18FDG-positron emission tomography (PET) and perfusion82Rb,201Tl, or99mTc scans were performed in 61 ischemic heart disease patients with VT. Hibernating areas were identified which was followed by three-dimensional PET reconstructions and integration with voltage maps to allow hybrid metabolic-electro-anatomic assessment of the arrhythmogenic substrate.
  
  
  RESULTS
  Of 61 patients with ischemic heart disease and refractory VT, 7 were found to have hibernating myocardium (13%). A total of 303 voltage points were obtained within hibernating myocardium (8.2 points per 10 cm2) and displayed abnormal voltage in 48.5 and 78.3% of bipolar and unipolar recordings, respectively, with significant heterogeneity of bipolar (p < 0.0001) and unipolar voltage measurements (p = 0.0004). Hibernating areas in 6 of 7 patients contained all three categories of bipolar voltage-defined scar (<0.5 mV), border zone (0.5-1.5 mV), and normal myocardium (>1.5 mV). The characteristics of local electrograms were also assessed and found abnormal in most recordings (76.6, 10.2% fractionated, 5.3% isolated potentials). Exit sites of clinical VTs were determined in 6 patients, of which 3 were located within hibernating myocardium.
  
  
  CONCLUSIONS
  Hibernating myocardium displays abnormal and heterogeneous electrical properties and seems to contribute to the substrate of VT. These observations may underlie the vulnerability to reentry and SCD in patients with hypoperfused yet viable myocardium.
authors.affiliation: Section of Cardiac Pacing and Electrophysiology, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Ayman A
authors.initials: AA
authors.lastname: Hussein
authors.affiliation: Division of Cardiology, University of Maryland School of Medicine, 22 S Greene St, Baltimore, MD, 21201, USA.
authors.forename: Michelle
authors.initials: M
authors.lastname: Niekoop
authors.affiliation: Division of Nuclear Medicine, University of Maryland School of Medicine, Baltimore, MD, USA.
authors.forename: Vasken
authors.initials: V
authors.lastname: Dilsizian
authors.affiliation: Division of Cardiology, University of Maryland School of Medicine, 22 S Greene St, Baltimore, MD, 21201, USA.
authors.forename: Yousra
authors.initials: Y
authors.lastname: Ghzally
authors.affiliation: Division of Cardiology, University of Maryland School of Medicine, 22 S Greene St, Baltimore, MD, 21201, USA.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Abdulghani
authors.affiliation: Division of Cardiology, University of Maryland School of Medicine, 22 S Greene St, Baltimore, MD, 21201, USA.
authors.forename: Ramazan
authors.initials: R
authors.lastname: Asoglu
authors.affiliation: Division of Nuclear Medicine, University of Maryland School of Medicine, Baltimore, MD, USA.
authors.forename: Wengen
authors.initials: W
authors.lastname: Chen
authors.affiliation: Division of Nuclear Medicine, University of Maryland School of Medicine, Baltimore, MD, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Smith
authors.affiliation: Division of Cardiology, University of Maryland School of Medicine, 22 S Greene St, Baltimore, MD, 21201, USA.
authors.forename: Vincent
authors.initials: V
authors.lastname: See
authors.affiliation: Division of Cardiology, University of Maryland School of Medicine, 22 S Greene St, Baltimore, MD, 21201, USA.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Shorofsky
authors.affiliation: Division of Cardiology, University of Maryland School of Medicine, 22 S Greene St, Baltimore, MD, 21201, USA. tdickfel@medicine.umaryland.edu.
authors.forename: Timm-Michael
authors.initials: TM
authors.lastname: Dickfeld
mesh_terms: D000368:Aged; D018780:Body Surface Potential Mapping / Q000379:methods*; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006329:Heart Conduction System / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D017682:Myocardial Stunning / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D049268:Positron-Emission Tomography / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017180:Tachycardia, Ventricular / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: Hibernating myocardium; Sudden death; Ventricular tachycardia