Effects of lifestyle changes and high-dose β-blocker therapy on exercise capacity in children, adolescents, and young adults with hypertrophic cardiomyopathy

Cardiol Young. 2015 Mar;25(3):501-10. doi: 10.1017/S1047951114000237. Epub 2014 Mar 10.

Abstract

Aim: 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.

Methods and 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.

Keywords: metoprolol.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adrenergic beta-Antagonists / administration & dosage
  • Adrenergic beta-Antagonists / therapeutic use*
  • Adult
  • Aging / psychology*
  • Blood Pressure / drug effects
  • Cardiomyopathy, Hypertrophic, Familial / drug therapy*
  • Cardiomyopathy, Hypertrophic, Familial / physiopathology
  • Child
  • Dose-Response Relationship, Drug
  • Exercise Test / methods
  • Exercise*
  • Female
  • Follow-Up Studies
  • Heart Rate / drug effects
  • Humans
  • Life Style*
  • Male
  • Metoprolol / administration & dosage
  • Metoprolol / therapeutic use
  • Propranolol / administration & dosage
  • Propranolol / therapeutic use
  • Random Allocation
  • Risk Factors
  • Sex Factors
  • Time Factors
  • Treatment Outcome
  • Young Adult

Substances

  • Adrenergic beta-Antagonists
  • Propranolol
  • Metoprolol