title: Potential proarrhythmic effect of biventricular pacing: fact or myth?
abstract: BACKGROUND
  Hemodynamic improvement from biventricular pacing is well documented; however, its electrophysiologic effects have not been systematically studied. Sporadic case reports suggest a proarrhythmic effect of biventricular pacing resulting primarily in polymorphic ventricular tachycardia/ventricular fibrillation (VT/VF).
  
  
  OBJECTIVE
  The purpose of this study was to report a series of patients in whom implantation of a biventricular system resulted in VT/VF storm with predominance of monomorphic VT.
  
  
  METHODS
  In a retrospective analysis of all biventricular implants over a 4-year period at a single medical center, we identified 5 of 145 patients (3.4%) who developed VT/VF after they were upgraded to a biventricular system. All patients were male, age 71 +/- 8 years, with ejection fraction of 0.25 +/- 0.1. Four of five patients had ischemic cardiomyopathy.
  
  
  RESULTS
  All patients developed incessant VT/VF within 1 week of implantation. Monomorphic VT of single morphology was noted in 3 of 5 patients, monomorphic VT of multiple morphologies in 1, and polymorphic VT/VF in 1. VT was managed by temporary discontinuation of biventricular pacing in all patients, amiodarone in 3 of 5, sotalol in 1, and beta-blocker in 1. During 11 +/- 7 months of follow-up, 4 of 5 patients remain alive and are arrhythmia-free.
  
  
  CONCLUSIONS
  Biventricular pacing may result in precipitation of VT/VF storm in a minority of patients with prior history of VT/VF. This may be the first case series reporting both monomorphic and polymorphic VT after an upgrade to a system with biventricular pacing capabilities. The arrhythmias can be managed by conventional therapy and may require temporary discontinuation of left ventricular pacing. This observation is relevant to patients receiving a biventricular pacemaker without an implantable cardioverter-defibrillator backup.
authors.affiliation: St. Elizabeth's Medical Center, Tufts University School of Medicine, Boston, Massachusetts 02135, USA. gunjanshukla@hotmail.com
authors.forename: Gunjan
authors.initials: G
authors.lastname: Shukla
authors.forename: G Muqtada
authors.initials: GM
authors.lastname: Chaudhry
authors.forename: Michael
authors.initials: M
authors.lastname: Orlov
authors.forename: Peter
authors.initials: P
authors.lastname: Hoffmeister
authors.forename: Charles
authors.initials: C
authors.lastname: Haffajee
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000368:Aged; D000638:Amiodarone / Q000627:therapeutic use; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000628:therapy; D002304:Cardiac Pacing, Artificial; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013015:Sotalol / Q000627:therapeutic use; D017180:Tachycardia, Ventricular / Q000188:drug therapy / Q000628:therapy*; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000188:drug therapy / Q000628:therapy*
chemical_list: D000319:Adrenergic beta-Antagonists; D000889:Anti-Arrhythmia Agents; D013015:Sotalol; D000638:Amiodarone