title: Effect of cardiac resynchronization on gradient reduction in patients with obstructive hypertrophic cardiomyopathy: preliminary study.
abstract: BACKGROUND
  The purpose of this study was to assess the effectiveness of cardiac resynchronization therapy (CRT) in terms of outflow tract gradient reduction and functional improvement in symptomatic patients with hypertrophic obstructive cardiomyopathy (HOCM) requiring implantable cardioverter-defibrillator (ICD) implantation.
  
  
  METHODS
  Eleven consecutive symptomatic HOCM patients with a significant (≥40 mmHg) gradient and indications for ICD, but without indications for resynchronization, underwent CRT-D implantation. Nine of them (four female, median age of 50 years) in whom the procedure succeeded were screened for New York Heart Association (NYHA) class, outflow gradient, mechanical dyssynchrony, QRS-width change, and 6-minute walking distance (6MWD) and peak oxygen consumption (VO(2)peak) improvement after 6 months and remotely.
  
  
  RESULTS
  After 6 months of pacing, NYHA class decreased (median 1 vs 2, respectively); peak (33 vs 84 mmHg) and mean (13 vs 38 mmHg) outflow tract gradients were reduced; and QRS width (143 vs 105 ms), intraventricular dyssynchrony (35 vs 55 ms), and VO(2)peak (19.5 vs 14.2 mL/kg/min) increased significantly (all P < 0.05) compared to baseline. In six of nine patients (67%), the peak gradient was reduced >50% and reached <40 mmHg. After a median of 36 months, the outflow gradient decreased even more (8 mmHg) and was significantly (P < 0.05) lower than after 6 months of CRT.
  
  
  CONCLUSIONS
  These preliminary data suggest that CRT seems to be an effective method of reducing the outflow tract gradient and improving the functional status of symptomatic HOCM patients requiring ICD implantation. Our findings need to be confirmed by more extensive studies.
authors.affiliation: Department of Cardiology, Congenital Heart Diseases and Electrotherapy, Medical University of Silesia, Silesian Center for Heart Disease, Zabrze, Poland. elfizab@poczta.onet.pl
authors.forename: Radosław
authors.initials: R
authors.lastname: Lenarczyk
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Woźniak
authors.forename: Oskar
authors.initials: O
authors.lastname: Kowalski
authors.forename: Adam
authors.initials: A
authors.lastname: Sokal
authors.forename: Patrycja
authors.initials: P
authors.lastname: Pruszkowska-Skrzep
authors.forename: Beata
authors.initials: B
authors.lastname: Sredniawa
authors.forename: Mariola
authors.initials: M
authors.lastname: Szulik
authors.forename: Teresa
authors.initials: T
authors.lastname: Zielińska
authors.forename: Tomasz
authors.initials: T
authors.lastname: Kukulski
authors.forename: Joanna
authors.initials: J
authors.lastname: Stabryła
authors.forename: Michał
authors.initials: M
authors.lastname: Mazurek
authors.forename: Jacek
authors.initials: J
authors.lastname: Białkowski
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Kalarus
mesh_terms: D000293:Adolescent; D000368:Aged; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications / Q000175:diagnosis* / Q000517:prevention & control*; D002648:Child; D017147:Defibrillators, Implantable; D005260:Female; D006333:Heart Failure / Q000150:complications / Q000175:diagnosis* / Q000517:prevention & control*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D016896:Treatment Outcome