title: Patients upgraded to cardiac resynchronization therapy due to pacing-induced cardiomyopathy are at low risk of life-threatening ventricular arrhythmias: a long-term cause-of-death analysis.
abstract: Upgrade to cardiac resynchronization therapy (CRT) should be offered to patients who have developed pacing-induced cardiomyopathy with conventional right ventricular pacing. The extent to which these patients would also benefit from defibrillator back-up at the time of CRT upgrade is, however, unknown.
  
  
  
  Retrospective observational cohort study of 199 patients with pacing-induced cardiomyopathy and no history of sustained ventricular arrhythmia, including 104 upgraded to CRT-Pacemaker (CRT-P) and 95 upgraded to CRT-Defibrillator (CRT-D). The incidence of ventricular arrhythmias and the risk of sudden arrhythmic death obtained through a cause-of-death analysis based on clinical data and necropsy results were assessed and compared between the two groups. During a mean follow-up of 66 ± 24 months, 40 (38.5%) CRT-P patients died: three from primary arrhythmic death, while the remaining died of different causes (especially progressive heart failure), giving an incidence of 6.2 sudden arrhythmic deaths per 1000 patient-years. No episode of sustained VT was observed in the study group. There were no sudden arrhythmic deaths in the CRT-D group during a shorter follow-up, but the small and non-significant difference in all-cause mortality between CRT-Pacemaker (CRT-P) and CRT-D groups was mostly accounted for by an increase in non-sudden death. Women upgraded to CRT were at particularly low risk of all-cause mortality compared with men (HR 0.232, P = 0.048).
  
  
  
  Our findings suggest that patients who develop pacing-induced cardiomyopathy and are upgraded to CRT may not derive any significant benefit from the addition of the defibrillator in the absence of a history of ventricular arrhythmias.
authors.affiliation: Cardiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge, UK.
authors.forename: Sergio
authors.initials: S
authors.lastname: Barra
authors.affiliation: Cardiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge, UK.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Duehmke
authors.affiliation: Cardiology Department, Barts Heart Centre, Barts Health NHS Trust, London, UK.
authors.forename: Rui
authors.initials: R
authors.lastname: Providencia
authors.affiliation: Cardiology Department, European Georges Pompidou Hospital, Paris, France.
authors.forename: Eloi
authors.initials: E
authors.lastname: Marijon
authors.affiliation: Cardiology Department, Clinique Pasteur, Toulouse, France.
authors.forename: Serge
authors.initials: S
authors.lastname: Boveda
authors.affiliation: Cardiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge, UK.
authors.forename: Munmohan
authors.initials: M
authors.lastname: Virdee
authors.affiliation: Cardiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge, UK.
authors.forename: Patrick
authors.initials: P
authors.lastname: Heck
authors.affiliation: Cardiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Fynn
authors.affiliation: Cardiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge, UK.
authors.forename: David
authors.initials: D
authors.lastname: Begley
authors.affiliation: Cardiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Grace
authors.affiliation: Cardiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge, UK.
authors.forename: Sharad
authors.initials: S
authors.lastname: Agarwal
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001145:Arrhythmias, Cardiac / Q000209:etiology / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects* / Q000379:methods / Q000401:mortality; D058406:Cardiac Resynchronization Therapy / Q000009:adverse effects / Q000401:mortality; D058409:Cardiac Resynchronization Therapy Devices; D009202:Cardiomyopathies / Q000209:etiology / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D002423:Cause of Death; D016757:Death, Sudden, Cardiac / Q000209:etiology / Q000517:prevention & control*; D017147:Defibrillators, Implantable; D018572:Disease-Free Survival; D004554:Electric Countershock / Q000009:adverse effects / Q000295:instrumentation* / Q000401:mortality; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
keywords: Cardiac resynchronization therapy; Cause of death; Implantable cardioverter-defibrillator; Pacemaker; Sudden arrhythmic death; Ventricular arrhythmias