title: Super-responders to cardiac resynchronization therapy remain at risk for ventricular arrhythmias and benefit from defibrillator treatment.
abstract: OBJECTIVE
  Mortality and ventricular arrhythmias are reduced in patients responding to cardiac resynchronization therapy (CRT). This response is accompanied by improvement in LVEF, and some patients even outgrow original eligibility criteria for implantable cardioverter-defibrillator (ICD) implantation. It is however unclear if these patients still benefit from ICD treatment. The current study aimed to evaluate if the incidence of ICD therapy is related to the extent of CRT response.
  
  
  RESULTS
  All patients who underwent primary prevention CRT-defibrillator implantation were included. They were divided into subgroups according to the reduction in LV end-systolic volume (LVESV) 6 months after implantation. Pre-defined subgroups were: negative responders (increased LVESV), non-responders (decreased LVESV 0-14%), responders (decreased LVESV 15-29%), and super-responders (decreased LVESV ≥30%). During a median follow-up of 57 months (25th-75th percentile 39-84), 512 patients were studied [101 (20%) negative responders, 101 (20%) non-responders, 149 (29%) responders, and 161 (31%) super-responders]. In the first year of follow-up super-responders received significantly less appropriate ICD therapy (3% vs. 12%; P < 0.001). The 5-year cumulative incidence of appropriate ICD therapy was 31% [95% confidence interval (CI) 19-43] in negative responders, 39% (95% CI 25-53) in non-responders, 34% (95% CI 25-43) in responders, and 27% (95% CI 18-35) in super-responders, respectively (p = 0.13).
  
  
  CONCLUSIONS
  The extent of CRT response was associated with a parallel reduction of appropriate device therapy during the first year of follow-up. Thereafter, no association was observed. Furthermore, 23% of super-responders were treated for potentially life-threatening arrhythmias and benefit from ICD treatment.
authors.affiliation: Department of Cardiology, Leiden University Medical Centre, Leiden, the Netherlands.
authors.forename: Aafke C
authors.initials: AC
authors.lastname: van der Heijden
authors.forename: Ulas
authors.initials: U
authors.lastname: Höke
authors.forename: Joep
authors.initials: J
authors.lastname: Thijssen
authors.forename: C Jan Willem
authors.initials: CJ
authors.lastname: Borleffs
authors.forename: Johannes B
authors.initials: JB
authors.lastname: van Rees
authors.forename: Enno T
authors.initials: ET
authors.lastname: van der Velde
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Schalij
authors.forename: Lieselot
authors.initials: L
authors.lastname: van Erven
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D058406:Cardiac Resynchronization Therapy / Q000009:adverse effects / Q000379:methods; D017147:Defibrillators, Implantable / Q000009:adverse effects*; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000401:mortality / Q000503:physiopathology / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D018570:Risk Assessment; D012720:Severity of Illness Index; D016019:Survival Analysis; D017180:Tachycardia, Ventricular / Q000517:prevention & control*; D020257:Ventricular Remodeling
keywords: Cardiac resynchronization therapy; Implantable cardioverter-defibrillator; Left ventricular reverse remodelling; Ventricular arrythmias