title: Clinical implications of midventricular obstruction in patients with hypertrophic cardiomyopathy.
abstract: OBJECTIVE
  We investigated the prevalence, clinical characteristics, and prognosis of hypertrophic cardiomyopathy (HCM) patients with midventricular obstruction (MVO).
  
  
  BACKGROUND
  Previous descriptions of patients with MVO have been confined to case reports or small patient series, and this subgroup of HCM patients has therefore remained underrecognized.
  
  
  METHODS
  The study population included 490 HCM patients. Left ventricular MVO was diagnosed when the peak midcavitary gradient was estimated to be ≥30 mm Hg.
  
  
  RESULTS
  MVO was identified in 46 patients (9.4%). Patients with MVO were more likely to be symptomatic than those without. MVO was found to be an independent determinant of HCM-related death in multivariate models (hazard ratio [HR]: 2.23, p = 0.016), and this trend was especially pronounced for the combined endpoint of sudden death and potentially lethal arrhythmic events (HR: 3.19, p < 0.001). Apical aneurysm formation was identified in 28.3% of patients with MVO and strongly predicted HCM-related death (HR: 3.47, p = 0.008) and the combined endpoint of sudden death and potentially lethal arrhythmic events (HR: 5.08, p < 0.001). In addition, MVO without apical aneurysm was also identified as an independent determinant of the combined endpoint of sudden death and potentially lethal arrhythmic events (HR: 2.43, p = 0.045).
  
  
  CONCLUSIONS
  This analysis identified MVO as an independent predictor of adverse outcomes, especially the combined endpoint of sudden death and potentially lethal arrhythmic events. Our results suggest that longer periods of exposure to MVO might lead to unfavorable consequences. They also support the principle that the presence of MVO in patients with HCM has important pathophysiological implications.
authors.affiliation: Department of Cardiology, Tokyo Women's Medical University, Tokyo, Japan. yuichiro24@celery.ocn.ne.jp
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Minami
authors.forename: Katsuya
authors.initials: K
authors.lastname: Kajimoto
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Terajima
authors.forename: Bun
authors.initials: B
authors.lastname: Yashiro
authors.forename: Dai
authors.initials: D
authors.lastname: Okayama
authors.forename: Shintaro
authors.initials: S
authors.lastname: Haruki
authors.forename: Takatomo
authors.initials: T
authors.lastname: Nakajima
authors.forename: Naomi
authors.initials: N
authors.lastname: Kawashiro
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Kawana
authors.forename: Nobuhisa
authors.initials: N
authors.lastname: Hagiwara
mesh_terms: D000328:Adult; D000368:Aged; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications* / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011379:Prognosis; D014463:Ultrasonography; D014694:Ventricular Outflow Obstruction / Q000150:complications* / Q000000981:diagnostic imaging*