Effects of cold exposure on submaximal exercise performance and adrenergic activation in patients with congestive heart failure and the effects of beta-adrenergic blockade ( carvedilol or metoprolol)

• Published in: The American journal of cardiology 2003-09, Vol.92 (5), p.548-553
• Main Authors: Blanchet, Martine, Ducharme, Anique, Racine, Normand, Rouleau, Jean-Lucien, Tardif, Jean-Claude, Juneau, Martin, Marquis, Johanne, Larivée, Lucie, Nigam, Anil, Fortier, Anick, White, Michel
• Format: Article
• Language: English
• Subjects: Adrenal glands; Adrenergic beta-Antagonists - pharmacology; Adrenergic beta-Antagonists - therapeutic use; Aged; Biological and medical sciences; Blood Gas Analysis; Carbazoles - pharmacology; Carbazoles - therapeutic use; Cardiovascular system; Carvedilol; Case-Control Studies; Cold Temperature - adverse effects; Dyspnea - etiology; Exercise; Exercise Test - drug effects; Exercise Tolerance - drug effects; Female; Heart failure; Heart Failure - complications; Heart Failure - drug therapy; Heart Failure - metabolism; Heart Failure - physiopathology; Humans; Male; Medical sciences; Metoprolol - pharmacology; Metoprolol - therapeutic use; Middle Aged; Norepinephrine - blood; Pharmacology. Drug treatments; Physical Endurance; Propanolamines - pharmacology; Propanolamines - therapeutic use; Prospective Studies; Receptors, Adrenergic - drug effects; Receptors, Adrenergic - physiology; Single-Blind Method; Stroke Volume - drug effects; Vasodilator agents. Cerebral vasodilators
• ISSN: 0002-9149; 1879-1913
• DOI: 10.1016/S0002-9149(03)00723-9

Patients with congestive heart failure (CHF) exhibit a decrease in maximal exercise capacity in response to a cold environment. The aim of this study was to further investigate the impact of cold exposure on submaximal exercise capacity, systemic adrenergic drive, and the effects of long-term β-adrenergic blockade on these parameters. Thirty-three patients with CHF, with exercise limited by dyspnea and left ventricular ejection fraction of 26 ± 4%, were randomized to receive metoprolol or carvedilol for 6 months. The observations were compared with 12 age-matched healthy volunteers. Maximal exercise performance with gas exchange analyses were assessed using a ramp protocol, and endurance capacity was measured using 2 constant-load exercise tests performed randomly at 20°C and −8°C. Healthy volunteers increased their submaximal exercise time by 20% (1,353 ± 455 [20°C] vs 1,635 ± 475 seconds [−8°C]; p