Effects of carvedilol on oxygen uptake and heart rate kinetics in patients with chronic heart failure at simulated altitude

Marlus Karsten, Mauro Contini, Claudia Cefalù, Gaia Cattadori, Pietro Palermo, Anna Apostolo, Maurizio Bussotti, Damiano Magrì, Elisabetta Salvioni, Stefania Farina, Susanna Sciomer, Aparecida Maria Catai, Piergiuseppe Agostoni

Research output: Contribution to journalArticle

Abstract

Background: The response to moderate exercise at altitude in heart failure (HF) is unknown.Methods and results: We evaluated 30 HF patients, (NYHA I-III, 25 M/5 F; 59 ± 10 years; LVEF = 39.6 ± 7.1%), in stable clinical conditions, treated with carvedilol at the maximal tolerated dose. We performed a maximal cardiopulmonary exercise test (CPET) with ramp protocol at sea level to evaluate patients' performance and two moderate intensity constant workload CPETs (50% of peak workload) at sea level (normoxia) and simulated altitude (hypoxia). Oxygen uptake (V•O2) and heart rate (HR) on-kinetics at constant workload were assessed calculating the time constant (τ) with a monoexponential equation. V•O2 and HR were higher in hypoxia (0.944 ± 0.233 vs 1.031 ± 0.264 l/min; 100 ± 23 vs 108 ± 22 bpm; p <0.001). On-kinetics showed a different behavior of τ being V•O2 faster in hypoxia (67.1 ± 23.0 vs. 56.3 ± 19.7 s; p = 0.026) and HR faster in normoxia (49.3 ± 19.4 vs. 62.2 ± 22.5 s; p = 0.018). Ten patients, who lowered oxygen kinetics in hypoxia, had greater HR increase during maximal CPET suggesting lower functional betablockade. The higher τ of V•O2 in hypoxia is likely to be due to a peripheral effect of carvedilol mediated either by β- or α-receptor.Conclusion: HF patients performing moderate exercise at 2000 m simulated altitude have 20% V•O2 increase without trouble at the beginning of exercise when treated with carvedilol.

Original languageEnglish
Pages (from-to)444-451
Number of pages8
JournalEuropean Journal of Preventive Cardiology
Volume19
Issue number3
DOIs
Publication statusPublished - Jun 2012

Keywords

  • betablockers
  • efficiency
  • Exercise test
  • hypoxia
  • oxygen consumption

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Epidemiology

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