Document Detail


The effects of long-term beta-blockade on the ventilatory responses to exercise in chronic heart failure.
MedLine Citation:
PMID:  15921802     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
AIMS: Chronic heart failure (CHF) patients complain of breathlessness and fatigue. Beta-blockers improve symptoms, echocardiograpahic variables and prognosis in CHF, but their effect on exercise capacity remains unclear. The aim of this study was to describe the effects of long-term beta-blocker therapy on metabolic gas exchange variables and ventilation during exercise in CHF patients.
METHODS: 42 patients with symptomatic heart failure due to left ventricular systolic dysfunction (ejection fraction 33.2 (8.2)) on loop diuretics and angiotensin-converting enzyme inhibitors or angiotensin II antagonists, underwent exercise testing with metabolic gas exchange. They were then initiated onto and uptitrated to the maximum tolerated dose of beta-blockers. After 1 year of follow-up, patients were invited back for repeat testing.
RESULTS: 35 patients attended for repeat exercise testing. Four patients had died, and three had not tolerated beta-blockade. After 1 year, exercise time was increased (487 (221) vs. 500 (217), p<0.05), and peak oxygen consumption and V(E)/V(CO(2)) slope were unchanged (20.9 (5.0) vs. 20.0 (5.4), p=0.15 and 36.7 (8.3) vs. 37.3 (7.8), p=0.70). Peak ventilation, (61.5 (12.9) vs. 57.1 (13.4), p<0.05), peak carbon dioxide production (1629 (404) vs. 1496 (375), p<0.02) and hence respiratory exchange ratio (1.02 (0.08) vs. 0.98 (0.06) p<0.02) and p<0.05) were reduced. Submaximal oxygen consumption and carbon dioxide production were lower at matched workloads. The slope relating symptoms to ventilation (Borg/V(E) slope) was less steep following beta-blockade (0.18 (0.09) vs. 0.15 (0.06), p<0.05).
CONCLUSION: Long term beta-blocker therapy increases exercise time but not peak oxygen consumption, and reduces peak carbon dioxide production. CHF patients are less symptomatic for a given ventilation during exercise following beta-blocker treatment.
Authors:
Klaus K A Witte; Simon Thackray; Nikolay P Nikitin; John G F Cleland; Andrew L Clark
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  European journal of heart failure     Volume:  7     ISSN:  1388-9842     ISO Abbreviation:  Eur. J. Heart Fail.     Publication Date:  2005 Jun 
Date Detail:
Created Date:  2005-05-30     Completed Date:  2005-09-27     Revised Date:  2011-06-08    
Medline Journal Info:
Nlm Unique ID:  100887595     Medline TA:  Eur J Heart Fail     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  612-7     Citation Subset:  IM    
Affiliation:
Academic Cardiology, Castle Hill Hospital, Castle Road, Cottingham Hull HU16 5JQ, UK. klauswitte@hotmail.com
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MeSH Terms
Descriptor/Qualifier:
Adrenergic beta-Antagonists / pharmacology*
Aged
Bisoprolol / pharmacology*
Carbazoles / pharmacology*
Exercise Test
Heart Failure / physiopathology*,  ultrasonography
Hemodynamics / drug effects
Humans
Middle Aged
Oxygen Consumption / drug effects
Propanolamines / pharmacology*
Respiration / drug effects*
Ventricular Function, Left / drug effects*
Chemical
Reg. No./Substance:
0/Adrenergic beta-Antagonists; 0/Carbazoles; 0/Propanolamines; 66722-44-9/Bisoprolol; 72956-09-3/carvedilol

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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