title: Association of intraventricular mechanical dyssynchrony with response to cardiac resynchronization therapy in heart failure patients with a narrow QRS complex.
abstract: OBJECTIVE
  current criteria for cardiac resynchronization therapy (CRT) are restricted to patients with a wide QRS complex (>120 ms). Overall, only 30% of heart failure patients demonstrate a wide QRS complex, leaving the majority of heart failure patients without this treatment option. However, patients with a narrow QRS complex exhibit left ventricular (LV) mechanical dyssynchrony, as assessed with echocardiography. To further elucidate the possible beneficial effect of CRT in heart failure patients with a narrow QRS complex, this two-centre, non-randomized observational study focused on different echocardiographic parameters of LV mechanical dyssynchrony reflecting atrioventricular, interventricular and intraventricular dyssynchrony, and the response to CRT in these patients.
  
  
  RESULTS
  a total of 123 consecutive heart failure patients with a narrow QRS complex (<120 ms) undergoing CRT was included at two centres. Several widely accepted measures of mechanical dyssynchrony were evaluated: LV filling ratio (LVFT/RR), LV pre-ejection time (LPEI), interventricular mechanical dyssynchrony (IVMD), opposing wall delay (OWD), and anteroseptal posterior wall delay with speckle tracking (ASPWD). Response to CRT was defined as a reduction ≥15% in left ventricular end-systolic volume at 6 months follow-up. Measures of dyssynchrony can frequently be observed in patients with a narrow QRS complex. Nonetheless, for LVFT/RR, LPEI, and IVMD, presence of predefined significant dyssynchrony is <20%. Significant intraventricular dyssynchrony is more widely observed in these patients. With receiver operator characteristic curve analyses, both OWD and ASPWD demonstrated usefulness in predicting response to CRT in narrow QRS patients with a cut-off value of 75 and 107 ms, respectively.
  
  
  CONCLUSIONS
  mechanical dyssynchrony can be widely observed in heart failure patients with a narrow QRS complex. In particular, intraventricular measures of mechanical dyssynchrony may be useful in predicting LV reverse remodelling at 6 months follow-up in heart failure patients with a narrow QRS complex, but with more stringent cut-off values than currently used in 'wide' QRS patients.
authors.affiliation: Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands.
authors.forename: Rutger J
authors.initials: RJ
authors.lastname: van Bommel
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Tanaka
authors.forename: Victoria
authors.initials: V
authors.lastname: Delgado
authors.forename: Matteo
authors.initials: M
authors.lastname: Bertini
authors.forename: Carel Jan Willem
authors.initials: CJ
authors.lastname: Borleffs
authors.forename: Nina
authors.initials: N
authors.lastname: Ajmone Marsan
authors.forename: Johannes
authors.initials: J
authors.lastname: Holzmeister
authors.forename: Frank
authors.initials: F
authors.lastname: Ruschitzka
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Schalij
authors.forename: Jeroen J
authors.initials: JJ
authors.lastname: Bax
authors.forename: John
authors.initials: J
authors.lastname: Gorcsan
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000150:complications* / Q000503:physiopathology; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D017147:Defibrillators, Implantable; D004452:Echocardiography; D005260:Female; D006333:Heart Failure / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000150:complications* / Q000503:physiopathology / Q000628:therapy; D020257:Ventricular Remodeling / Q000502:physiology*