title: Exercise echocardiography in asymptomatic HCM: exercise capacity, and not LV outflow tract gradient predicts long-term outcomes.
abstract: OBJECTIVE
  This study sought to assess long-term outcomes in asymptomatic or minimally symptomatic patients with hypertrophic cardiomyopathy (HCM) who underwent exercise echocardiography, without invasive therapies for relief of left ventricular outflow tract (LVOT) obstruction.
  
  
  BACKGROUND
  Many HCM patients present with LVOT obstruction, mitral regurgitation (MR), and diastolic dysfunction, often requiring invasive therapies for symptomatic relief. However, a significant proportion of truly asymptomatic patients can be closely monitored. In HCM patients, exercise echocardiography has been shown to be a useful assessment of functional capacity and risk stratification.
  
  
  METHODS
  We included 426 HCM patients (44 ± 14 years; 78% men) undergoing exercise echocardiography, excluding hypertensive heart disease of elderly, ejection fraction <50% and invasive therapy (myectomy or alcohol ablation) during follow-up. Clinical, echocardiographic (LV thickness, LVOT gradient, and MR) and exercise variables (percent of age-sex predicted metabolic equivalents [METs] and heart rate recovery [HRR] at 1 min post-exercise) were recorded. A composite endpoint of death, appropriate internal defibrillator discharge, and admission for congestive heart failure was recorded.
  
  
  RESULTS
  Patients were asymptomatic or minimally symptomatic on history, but 82% of patients achieved <100% of age-sex predicted METs, and 43% had ≥II+ post-stress MR. The mean LV septal thickness, post-exercise LVOT gradient, and HRR were 2.0 ± 0.5 cm, 62 ± 47 mm Hg, and 31 ± 14 beats/min, respectively. During a mean follow-up of 8.7 ± 3 years, there were 52 events (12%). Patients achieving >100% of age-sex predicted METs had 1% event rate versus 12% in those achieving <85%. On stepwise multivariate survival analysis, percent of age-sex predicted METs (hazard ratio [HR]: 0.76; 95% confidence interval [CI]: 0.64 to 0.90), abnormal HRR (HR: 0.89; 95% CI: 0.82 to 0.97), and atrial fibrillation (HR: 2.73; 95% CI: 1.30 to 5.74) (overall, p < 0.001) independently predicted outcomes.
  
  
  CONCLUSIONS
  In asymptomatic or minimally symptomatic HCM patients, exercise stress testing provides excellent risk stratification, with a low event rate in patients achieving >100% of predicted METs.
authors.affiliation: Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio. Electronic address: desaim2@ccf.org.
authors.forename: Milind Y
authors.initials: MY
authors.lastname: Desai
authors.affiliation: Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Aditya
authors.initials: A
authors.lastname: Bhonsale
authors.affiliation: Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Parag
authors.initials: P
authors.lastname: Patel
authors.affiliation: Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Peyman
authors.initials: P
authors.lastname: Naji
authors.affiliation: Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Smedira
authors.affiliation: Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Maran
authors.initials: M
authors.lastname: Thamilarasan
authors.affiliation: Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Bruce W
authors.initials: BW
authors.lastname: Lytle
authors.affiliation: Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Harry M
authors.initials: HM
authors.lastname: Lever
mesh_terms: D000328:Adult; D002312:Cardiomyopathy, Hypertrophic / Q000000981:diagnostic imaging* / Q000503:physiopathology; D025401:Echocardiography, Stress / Q000379:methods*; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012146:Rest / Q000502:physiology; D012189:Retrospective Studies; D013997:Time Factors; D016277:Ventricular Function, Left / Q000502:physiology*
keywords: AF; CHF; HCM; HR; HRR; ICD; LVOT; METs; MR; VT; atrial fibrillation; congestive heart failure; exercise echocardiography; hazard ratio; heart rate recovery; hypertrophic cardiomyopathy; implantable cardioverter-defibrillator; left ventricular outflow tract; metabolic equivalents; mitral regurgitation; outcomes; ventricular tachycardia