title: CMR-based identification of critical isthmus sites of ischemic and nonischemic ventricular tachycardia.
abstract: OBJECTIVE
  This study evaluates whether contrast-enhanced (CE) cardiac magnetic resonance (CMR) can be used to identify critical isthmus sites for ventricular tachycardia (VT) in ischemic and nonischemic heart disease.
  
  
  BACKGROUND
  Fibrosis interspersed with viable myocytes may cause re-entrant VT. CE-CMR has the ability to accurately delineate fibrosis.
  
  
  METHODS
  Patients who underwent VT ablation with CE-CMR integration were included. After the procedure, critical isthmus sites (defined as sites with a ≥11 of 12 pacemap, concealed entrainment, or VT termination during ablation) were projected on CMR-derived 3-dimensional (3D) scar reconstructions. The scar transmurality and signal intensity at all critical isthmus, central isthmus, and exit sites were compared to the average of the entire scar. The distance to >75% transmural scar and to the core-border zone (BZ) transition was calculated. The area within 5 mm of both >75% transmural scar and the core-BZ transition was calculated.
  
  
  RESULTS
  In 44 patients (23 ischemic and 21 nonischemic, left ventricular ejection fraction 44 ± 12%), a total of 110 VTs were induced (cycle length 290 ± 67 ms). Critical isthmus sites were identified for 78 VTs (71%) based on ≥11 of 12 pacemaps (67 VTs), concealed entrainment (10 VTs), and/or termination (30 VTs). The critical isthmus sites, and in particular central isthmus sites, had high scar transmurality and signal intensity compared with the average of the entire scar. Of the pacemap, concealed entrainment, and termination sites, 74%, 100%, and 84% were within 5 mm of >75% transmural scar, and 67%, 100%, and 94% were within 5 mm of the core-BZ transition, respectively. The areas within 5 mm of both >75% transmural scar and the core-BZ transition (median 13% of LV) contained all concealed entrainment sites and 77% of termination sites.
  
  
  CONCLUSIONS
  Both in ischemic and nonischemic VT, critical isthmus sites are typically located in close proximity to the CMR-derived core-BZ transition and to >75% transmural scar. These findings suggest that CMR-derived scar characteristics may guide to critical isthmus sites during VT ablation.
authors: Department of Cardiology, Leiden University Medical Centre, Leiden, the Netherlands.
authors: Sebastiaan R D
authors: SR
authors: Piers
authors: Department of Radiology, Division of Image Processing, Leiden University Medical Centre, Leiden, the Netherlands.
authors: Qian
authors: Q
authors: Tao
authors: Department of Cardiology, Leiden University Medical Centre, Leiden, the Netherlands.
authors: Marta
authors: M
authors: de Riva Silva
authors: Department of Cardiology, Leiden University Medical Centre, Leiden, the Netherlands.
authors: Hans-Marc
authors: HM
authors: Siebelink
authors: Department of Cardiology, Leiden University Medical Centre, Leiden, the Netherlands.
authors: Martin J
authors: MJ
authors: Schalij
authors: Department of Radiology, Division of Image Processing, Leiden University Medical Centre, Leiden, the Netherlands.
authors: Rob J
authors: RJ
authors: van der Geest
authors: Department of Cardiology, Leiden University Medical Centre, Leiden, the Netherlands. Electronic address: K.Zeppenfeld@lumc.nl.
authors: Katja
authors: K
authors: Zeppenfeld
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial; D009202:Cardiomyopathies / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D017115:Catheter Ablation; D002921:Cicatrix / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology; D003287:Contrast Media; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D005355:Fibrosis; D019786:Gadolinium DTPA; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D009206:Myocardium / Q000473:pathology*; D011237:Predictive Value of Tests; D013318:Stroke Volume; D017180:Tachycardia, Ventricular / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery; D013997:Time Factors; D016896:Treatment Outcome; D016277:Ventricular Function, Left
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA
keywords: cardiac magnetic resonance; catheter ablation; image integration; myocardial infarction; nonischemic cardiomyopathy; ventricular tachycardia