title: Left ventricular sphericity independently predicts appropriate implantable cardioverter-defibrillator therapy.
abstract: BACKGROUND
  Whether echocardiographic markers of remodeling are associated with ventricular tachyarrhythmias is unknown.
  
  
  OBJECTIVE
  The purpose of this study was to determine whether a transthoracic echocardiographic (TTE) marker of spherical left ventricular (LV) remodeling is associated with appropriate implantable cardioverter-defibrillator (ICD) therapy in patients with primary prevention ICDs.
  
  
  METHODS
  From TTE images, we calculated sphericity index (SI), the ratio of biplane LV end-diastolic volume to the volume of a hypothetical sphere with a diameter of the LV end-diastolic length, and examined the relation between SI and therapy for ventricular tachyarrhythmias in 278 patients with primary prevention ICDs and in 50 controls without structural heart disease or ventricular arrhythmias.
  
  
  RESULTS
  SI in normal healthy adult subjects and in subjects receiving ICDs was 0.44 ± 0.02 and 0.65 ± 0.04, respectively (P <.001). Median time to first appropriate ICD therapy was significantly shorter in ICD patients with SI in the upper vs lower 50% of SI values (1.40 vs 2.38 years, P = .02 for conventional ICD patients; 1.54 vs 2.65 years, P = .02 for cardiac resynchronization therapy-defibrillator [CRT-D] patients). In multivariable Cox regression analysis, SI in the upper 50% was independently associated with appropriate ICD therapy after multivariable adjustment (hazard ratio 2.2, P = .03 for ICD cohort; hazard ratio 4.4, P = .01 for CRT-D cohort). SI was not associated with total mortality in either cohort.
  
  
  CONCLUSIONS
  SI is associated with appropriate ICD therapy, but not total mortality, in patients receiving primary prevention ICDs. These observations suggest spherical LV remodeling may predispose to ventricular arrhythmias. Furthermore, SI appears to add predictive accuracy for appropriate ICD therapy in patients with reduced ejection fraction.
authors.affiliation: Department of Medicine (Cardiovascular Institute), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts.
authors.forename: Yehoshua C
authors.initials: YC
authors.lastname: Levine
authors.affiliation: Department of Medicine (Cardiovascular Institute), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts.
authors.forename: Jason
authors.initials: J
authors.lastname: Matos
authors.affiliation: Division of Electrophysiology, VA Healthcare System of Boston, Harvard Medical School, Boston, Massachusetts.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Rosenberg
authors.affiliation: Department of Medicine (Cardiovascular Institute), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts; Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts.
authors.forename: Warren J
authors.initials: WJ
authors.lastname: Manning
authors.affiliation: Department of Medicine (Cardiovascular Institute), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Josephson
authors.affiliation: Department of Medicine (Cardiovascular Institute), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts. Electronic address: abuxton@bidmc.harvard.edu.
authors.forename: Alfred E
authors.initials: AE
authors.lastname: Buxton
mesh_terms: D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D016757:Death, Sudden, Cardiac / Q000209:etiology / Q000517:prevention & control*; D017147:Defibrillators, Implantable; D003936:Diagnosis, Computer-Assisted; D004452:Echocardiography / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D017180:Tachycardia, Ventricular / Q000150:complications / Q000175:diagnosis / Q000628:therapy; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000503:physiopathology; D020257:Ventricular Remodeling
keywords: Implantable cardioverter-defibrillator; Left ventricular sphericity; Remodeling; Risk stratification; Ventricular arrhythmia