title: Effects of lifestyle changes and high-dose β-blocker therapy on exercise capacity in children, adolescents, and young adults with hypertrophic cardiomyopathy.
abstract: OBJECTIVE
  The use of β-blocker therapy in asymptomatic patients with hypertrophic cardiomyopathy is controversial. This study evaluates the effect of lifestyle changes and high-dose β-blocker therapy on their exercise capacity.
  
  
  RESULTS
  A total of 29 consecutive newly diagnosed asymptomatic patients with familial hypertrophic cardiomyopathy, median age 15 years (range 7-25), were recruited. In all, 16 patients with risk factors for sudden death were treated with propranolol if no contraindications, or equivalent doses of metoprolol; 13 with no risk factors were randomised to metoprolol or no active treatment. Thus, there were three treatment groups, non-selective β-blockade (n=10, propranolol 4.0-11.6 mg/kg/day), selective β-blockade (n=9, metoprolol 2.7-5.9 mg/kg/day), and randomised controls (n=10). All were given recommendations for lifestyle modifications, and reduced energetic exercise significantly (p=0.002). Before study entry, and after 1 year, all underwent bicycle exercise tests with a ramp protocol. There were no differences in exercise capacity between the groups at entry, or follow-up, when median exercise capacity in the groups were virtually identical (2.4, 2.3, and 2.3 watt/kg and 55, 55, and 55 watt/(height in metre) 2 in control, selective, and non-selective groups, respectively. Maximum heart rate decreased in the selective (-29%, p=0.04) and non-selective (-24%, p=0.002) groups. No patient developed a pathological blood-pressure response to exercise because of β-blocker therapy. Boys were more frequently risk-factor positive than girls (75% versus 33%, p=0.048) and had higher physical activity scores than girls at study-entry (p=0.011).
  
  
  CONCLUSIONS
  Neither selective nor non-selective β-blockade causes significant reductions in exercise capacity in patients with hypertrophic cardiomyopathy above that induced by lifestyle changes.
authors.affiliation: 1Department of Paediatrics,Institute of Clinical Sciences,The Sahlgrenska Academy,University of Gothenburg,Gothenburg,Sweden.
authors.forename: Ewa-Lena
authors.initials: EL
authors.lastname: Bratt
authors.affiliation: 1Department of Paediatrics,Institute of Clinical Sciences,The Sahlgrenska Academy,University of Gothenburg,Gothenburg,Sweden.
authors.forename: Ingegerd
authors.initials: I
authors.lastname: Östman-Smith
mesh_terms: D000293:Adolescent; D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000627:therapeutic use*; D000328:Adult; D000375:Aging / Q000523:psychology*; D001794:Blood Pressure / Q000187:drug effects; D024741:Cardiomyopathy, Hypertrophic, Familial / Q000188:drug therapy* / Q000503:physiopathology; D002648:Child; D004305:Dose-Response Relationship, Drug; D015444:Exercise; D005080:Exercise Test / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008019:Life Style; D008297:Male; D008790:Metoprolol / Q000008:administration & dosage / Q000627:therapeutic use; D011433:Propranolol / Q000008:administration & dosage / Q000627:therapeutic use; D011897:Random Allocation; D012307:Risk Factors; D012737:Sex Factors; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000319:Adrenergic beta-Antagonists; D011433:Propranolol; D008790:Metoprolol
keywords: metoprolol