title: Human histopathology of electroanatomic mapping after cooled-tip radiofrequency ablation to treat ventricular tachycardia in remote myocardial infarction.
abstract: BACKGROUND
  Catheter ablation of ventricular tachycardia (VT) in remote myocardial infarction (MI) often requires excessive mapping procedures. Documentation of the electrical substrate via electrogram amplitude may help to identify regions of altered myocardium resembling exit areas of reentrant VTs.
  
  
  RESULTS
  A patient with multiple symptomatic monomorphic VTs (biventricular ICD, remote MI) underwent electroanatomic substrate mapping (CARTOtrade mark) for VT ablation. Regions of scar (bipolar electrogram amplitudes <or=0.5 mV), normal myocardium (>or=1.5 mV), and "altered" myocardium (0.5-1.5 mV) were identified. Ablation was directed to regions with "altered" myocardium based on pace map correlation. After ablation the clinical VT did not reoccur. The patient died due to worsening of heart failure 7 days afterward. During postmortal evaluation specified sites of electroanatomic mapping were correlated to histopathological findings. Annotated scar areas were documented to consist of areas with massive fibrosis (>or=80% of mural composition). Ablations were found to span through regions with intermediate fibrosis (21-79%) mapped as "altered" myocardium. Ablation produced transmural coagulation necrosis of mesh-like fibrotic tissue with interspersed remnants of myocardial cells up to a maximum depth of 7.0 mm. Subendocardial intramural bleedings were universal findings 7 days after ablation.
  
  
  CONCLUSIONS
  Electroanatomic substrate mapping for VT ablation sufficiently identified regions of scar and normal myocardium. Regions with bipolar electrogram amplitudes between 0.5 and 1.5 mV were found to correlate to areas of "intermediate" fibrosis (21-79%) with only remnant strands of myocardial cells and were identified as target region for ablation. Cooled-tip endocardial radiofrequency ablation lead to transmural coagulation necrosis up to a depth of 7.0 mm.
authors.affiliation: BG Kliniken Bergmannsheil, Medical Clinic II (Cardiology), University of Bochum, Bochum, Germany. thomas.deneke@ruhruni-bochum.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Deneke
authors.forename: Klaus-Michael
authors.initials: KM
authors.lastname: Müller
authors.forename: Bernd
authors.initials: B
authors.lastname: Lemke
authors.forename: Thomas
authors.initials: T
authors.lastname: Lawo
authors.forename: Bernd
authors.initials: B
authors.lastname: Calcum
authors.forename: Marlene
authors.initials: M
authors.lastname: Helwing
authors.forename: Andreas
authors.initials: A
authors.lastname: Mügge
authors.forename: Peter H
authors.initials: PH
authors.lastname: Grewe
mesh_terms: D000368:Aged; D017115:Catheter Ablation; D022062:Electrophysiologic Techniques, Cardiac; D017809:Fatal Outcome; D006801:Humans; D008297:Male; D009203:Myocardial Infarction / Q000150:complications* / Q000473:pathology; D017180:Tachycardia, Ventricular / Q000209:etiology / Q000473:pathology* / Q000601:surgery*