Effects of lifestyle changes and high-dose β-blocker therapy on exercise capacity in children, adolescents, and young adults with hypertrophic cardiomyopathy.
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.
['Bratt|Ewa-Lena|EL|', 'Östman-Smith|Ingegerd|I|']
D000293:Adolescent D000319:Adrenergic beta-Antagonists D000328:Adult D000375:Aging D001794:Blood Pressure D024741:Cardiomyopathy, Hypertrophic, Familial D002648:Child D004305:Dose-Response Relationship, Drug D015444:Exercise D005080:Exercise Test D005260:Female D005500:Follow-Up Studies D006339:Heart Rate D006801:Humans D008019:Life Style D008297:Male D008790:Metoprolol D011433:Propranolol D011897:Random Allocation D012307:Risk Factors D012737:Sex Factors D013997:Time Factors D016896:Treatment Outcome D055815:Young Adult
metoprolol