title: Electrical storm induced by cardiac resynchronization therapy is determined by pacing on epicardial scar and can be successfully managed by catheter ablation.
abstract: BACKGROUND
  The mechanism of cardiac resynchronization therapy (CRT)-induced proarrhythmia remains unknown. We postulated that pacing from a left ventricular (LV) lead positioned on epicardial scar can facilitate re-entrant ventricular tachycardia. The aim of this study was to investigate the relationship between CRT-induced proarrhythmia and LV lead location within scar.
  
  
  RESULTS
  Twenty-eight epicardial and 63 endocardial maps, obtained from 64 CRT patients undergoing ventricular tachycardia ablation, were analyzed. A positive LV lead/scar relationship, defined as a lead tip positioned on scar/border zone, was determined by overlaying fluoroscopic projections with LV electroanatomical maps. CRT-induced proarrhythmia occurred in 8 patients (12.5%). They all presented early with electrical storm (100% versus 39% of patients with no proarrhythmia; P<0.01), requiring temporary biventricular pacing discontinuation in half of cases. They more frequently presented with heart failure/cardiogenic shock (50% versus 7%; P<0.01), requiring intensive care management. Ventricular tachycardia was re-entrant in all. The LV lead location within epicardial scar was significantly more frequent in the proarrhythmia group (60% versus 9% P=0.03 on epicardial bipolar scar, 80% versus 17% P=0.02 on epicardial unipolar scar, and 80% versus 17% P=0.02 on any-epicardial scar). Ablation was performed within epicardial scar, close to the LV lead, and allowed CRT reactivation in all patients.
  
  
  CONCLUSIONS
  CRT-induced proarrhythmia presented early with electrical storm and was associated with an LV lead positioning within epicardial scar. Catheter ablation allowed for resumption of biventricular stimulation in all patients.
authors.affiliation: From the Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Roque
authors.affiliation: From the Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Trevisi
authors.affiliation: From the Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy.
authors.forename: John
authors.initials: J
authors.lastname: Silberbauer
authors.affiliation: From the Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy.
authors.forename: Teresa
authors.initials: T
authors.lastname: Oloriz
authors.affiliation: From the Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy.
authors.forename: Hiroya
authors.initials: H
authors.lastname: Mizuno
authors.affiliation: From the Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Baratto
authors.affiliation: From the Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy.
authors.forename: Caterina
authors.initials: C
authors.lastname: Bisceglia
authors.affiliation: From the Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy.
authors.forename: Nicoleta
authors.initials: N
authors.lastname: Sora
authors.affiliation: From the Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Marzi
authors.affiliation: From the Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Radinovic
authors.affiliation: From the Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Guarracini
authors.affiliation: From the Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy.
authors.forename: Pasquale
authors.initials: P
authors.lastname: Vergara
authors.affiliation: From the Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Sala
authors.affiliation: From the Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Paglino
authors.affiliation: From the Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Gulletta
authors.affiliation: From the Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy.
authors.forename: Patrizio
authors.initials: P
authors.lastname: Mazzone
authors.affiliation: From the Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Cireddu
authors.affiliation: From the Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Maccabelli
authors.affiliation: From the Arrhythmia Unit and Electrophysiology Laboratories, Ospedale San Raffaele, Milan, Italy. dellabella.paolo@hsr.it.
authors.forename: Paolo
authors.initials: P
authors.lastname: Della Bella
mesh_terms: D000200:Action Potentials; D000368:Aged; D000369:Aged, 80 and over; D058406:Cardiac Resynchronization Therapy / Q000009:adverse effects*; D058409:Cardiac Resynchronization Therapy Devices; D017115:Catheter Ablation; D002921:Cicatrix / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D010496:Pericardium / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D012307:Risk Factors; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome; D016277:Ventricular Function, Left; D016278:Ventricular Function, Right
keywords: cardiac resynchronization therapy; catheter ablation; tachycardia, ventricular