title: Does pacemaker implantation provide long-term benefits in severe obstructive hypertrophic cardiomyopathy?
abstract: OBJECTIVE
  About 25% of patients with obstructive hypertrophic cardiomyopathy (HCM) remain symptomatic despite optimal medical treatment. Some may benefit from pacemaker implantation. The aim of this study was to determine the effect of pacemaker implantation on the left ventricular outflow tract (LVOT) gradient, the maximum thickness of the left ventricle, and functional capacity.
  
  
  METHODS
  In total, 72 patients with obstructive HCM and incapacitating symptoms underwent pacemaker implantation. Clinical examination, echocardiography (in 61 patients) and treadmill testing (in 34 patients) were performed before and after implantation.
  
  
  RESULTS
  Subjective functional capacity, as assessed using the New York Heart Association (NYHA) classification, improved in 43.1% of patients, but treadmill testing showed no change. There were significant reductions in subaortic gradient, from a median of 87.0 mmHg (interquartile range [IQR] 61.5-115.2 mmHg) to 30.0 mmHg (IQR 18.0-54.5 mmHg; P< .001), and maximum left ventricular thickness, from 22.1+/-4.5 mm to 19.8+/-3.6 mm (P=.001). Univariate analysis identified two factors associated with clinical improvement: female sex (odds ratio [OR]=3.43; P=.020) and functional class III/IV (OR=4.17; P=.009). On multivariate analysis, only functional class III/IV remained a significant predictor (OR=3.12; P=.048).
  
  
  CONCLUSIONS
  In patients with obstructive HCM and incapacitating symptoms, pacemaker implantation reduced the LVOT gradient and the maximum left ventricular thickness, but only 43.1% of patients experienced clinical improvement. The only factor predictive of improvement was advanced NYHA functional class.
authors.affiliation: Servicio de Cardiología. Hospital General Universitario de Alicante, Alicante, España.
authors.forename: Míriam
authors.initials: M
authors.lastname: Sandín
authors.forename: Francisco
authors.initials: F
authors.lastname: Marín
authors.forename: Francisco
authors.initials: F
authors.lastname: Cambronero
authors.forename: Vicente
authors.initials: V
authors.lastname: Climent
authors.forename: César
authors.initials: C
authors.lastname: Caro
authors.forename: Juan Gabriel
authors.initials: JG
authors.lastname: Martínez
authors.forename: Antonio García
authors.initials: AG
authors.lastname: Honrubia
authors.forename: Arcadio
authors.initials: A
authors.lastname: García Alberola
authors.forename: Gonzalo
authors.initials: G
authors.lastname: de la Morena
authors.forename: Mariano
authors.initials: M
authors.lastname: Valdés
authors.forename: Francisco
authors.initials: F
authors.lastname: Sogorb
mesh_terms: D002312:Cardiomyopathy, Hypertrophic / Q000628:therapy*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013997:Time Factors