title: The prognostic importance of left ventricular outflow obstruction in hypertrophic cardiomyopathy varies in relation to the severity of symptoms.
abstract: OBJECTIVE
  The aim of this study was to investigate whether the prognostic importance of left ventricular (LV) outflow obstruction in hypertrophic cardiomyopathy (HCM) is influenced by other predictors of morbidity and mortality.
  
  
  BACKGROUND
  It remains unknown whether the effect of outflow obstruction on clinical outcome in HCM is influenced by other determinants of survival.
  
  
  METHODS
  We assessed the impact of severity of symptoms, LV wall thickness, atrial fibrillation, and age on the prognostic importance of outflow obstruction in a large HCM population.
  
  
  RESULTS
  Of 526 consecutive HCM patients, 141 (27%) had outflow obstruction. During a follow-up of 4.5 +/- 4.1 years, 34 patients died of HCM. The incidence of cardiovascular death was significantly higher among patients with LV obstruction than among those without obstruction (relative risk [RR] = 2.14; p = 0.02). The prognostic power of the outflow gradient changed in relation to severity of symptoms (p = 0.024). At initial evaluation, LV obstruction was a significant predictor of cardiovascular mortality only in New York Heart Association (NYHA) functional class I to II patients (hazard ratio [HR] = 2.38; p = 0.025). During follow-up, at time of development of severe symptoms, the outflow gradient lost its prognostic significance (HR = 1.18; p = 0.66), whereas NYHA functional class III to IV was associated with an eight-fold increase in risk of cardiovascular mortality (HR = 7.90; p < 0.001).
  
  
  CONCLUSIONS
  In patients with HCM, the prognostic importance of LV outflow obstruction varies in relation to the severity of symptoms. In patients with mild or no symptoms, obstruction is an important predictor of cardiovascular death. After development of severe symptoms, NYHA functional class becomes the dominant marker of prognosis independently of the presence of an outflow gradient.
authors.affiliation: Divisione di Cardiologia, Università di Roma La Sapienza, Ospedale Sant'Andrea, Via Grottarossa 1035-1039, 00189 Rome, Italy. camillo.autore@uniroma1.it
authors.forename: Camillo
authors.initials: C
authors.lastname: Autore
authors.forename: Paola
authors.initials: P
authors.lastname: Bernabò
authors.forename: Caterina Stella
authors.initials: CS
authors.lastname: Barillà
authors.forename: Paolo
authors.initials: P
authors.lastname: Bruzzi
authors.forename: Paolo
authors.initials: P
authors.lastname: Spirito
mesh_terms: D002312:Cardiomyopathy, Hypertrophic / Q000150:complications / Q000000981:diagnostic imaging / Q000401:mortality* / Q000473:pathology; D005260:Female; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012720:Severity of Illness Index; D016019:Survival Analysis; D014463:Ultrasonography; D014694:Ventricular Outflow Obstruction / Q000150:complications / Q000000981:diagnostic imaging / Q000401:mortality* / Q000473:pathology