title: Mechanical dyssynchrony after cardiac resynchronization therapy for severely symptomatic heart failure is associated with risk for ventricular arrhythmias.
abstract: BACKGROUND
  Risk factors for ventricular arrhythmias after cardiac resynchronization defibrillator therapy (CRT-D) for severely symptomatic heart failure are of clinical importance but are not clearly defined. The objective of this study was to test the hypothesis that mechanical dyssynchrony after CRT-D is a risk factor for ventricular arrhythmias.
  
  
  METHODS
  A total of 266 consecutive CRT-D patients with class III or IV heart failure, QRS duration ≥120 msec, and ejection fractions ≤ 35% were prospectively studied. Dyssynchrony was assessed before and 6 months after CRT-D using speckle-tracking radial strain anteroseptal-to-posterior wall delay, predefined as ≥130 msec. Ventricular arrhythmias were predefined as appropriate antitachycardia pacing or shock, and the combined end point of ventricular arrhythmias, death, transplantation, or left ventricular assist device implantation was followed over 2 years.
  
  
  RESULTS
  Of the initial 266 patients, 11 died, five underwent transplantation, three received left ventricular assist devices before their 6-month echocardiographic examinations, 19 (7%) had inadequate speckle-tracking at 6-month follow-up, and 27 (10%) were lost to follow-up. Accordingly, the study group consisted of 201 patients. Dyssynchrony after CRT-D was observed in 79 (39%) and was associated with a significantly higher ventricular arrhythmic event rate: 21% (P < .001) with persistent dyssynchrony and 35% (P < .001) with new dyssynchrony, compared with 8% with no dyssynchrony after CRT-D. The combined end point of ventricular arrhythmias, death, transplantation, or left ventricular assist device implantation was significantly associated with dyssynchrony after CRT-D (hazard ratio, 2.53; 95% confidence interval, 1.49-4.28; P = .001). Dyssynchrony after CRT-D was associated with ventricular arrhythmias or death in patient subgroups by cardiomyopathy type, QRS width, and morphology (P < .05 for all).
  
  
  CONCLUSIONS
  Persistent or new radial dyssynchrony after CRT-D in severely symptomatic patients with heart failure with widened QRS complexes and reduced ejection fractions was associated with an increased rate of ventricular arrhythmias or death and appears to be a marker for a less favorable prognosis.
authors.affiliation: The University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Kristina H
authors.initials: KH
authors.lastname: Haugaa
authors.affiliation: The University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Josef J
authors.initials: JJ
authors.lastname: Marek
authors.affiliation: The University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Ahmed
authors.affiliation: The University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Keiko
authors.initials: K
authors.lastname: Ryo
authors.affiliation: The University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Evan C
authors.initials: EC
authors.lastname: Adelstein
authors.affiliation: The University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: David
authors.initials: D
authors.lastname: Schwartzman
authors.affiliation: The University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Samir
authors.initials: S
authors.lastname: Saba
authors.affiliation: The University of Pittsburgh, Pittsburgh, Pennsylvania. Electronic address: gorcsanj@upmc.edu.
authors.forename: John
authors.initials: J
authors.lastname: Gorcsan
mesh_terms: D000368:Aged; D058406:Cardiac Resynchronization Therapy / Q000009:adverse effects*; D004452:Echocardiography / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000150:complications / Q000000981:diagnostic imaging / Q000628:therapy*; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D008297:Male; D011446:Prospective Studies; D012720:Severity of Illness Index; D017180:Tachycardia, Ventricular / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D016896:Treatment Outcome
keywords: Cardiac resynchronization therapy; Dyssynchrony; Echocardiography; Pacemaker; Ventricular arrhythmia