Carvedilol reduces the inappropriate increase of ventilation during exercise in heart failure patients.
OBJECTIVE
To evaluate the effects of beta-blockers on ventilation in heart failure patients. Indeed, beta-blockers ameliorate the clinical condition and cardiac function of heart failure patients, but not exercise capacity. Because ventilation is inappropriately elevated in heart failure patients due to overactive reflexes from ergoreceptors and chemoreceptors, we hypothesized that beta-blockers can elicit their positive clinical effects through a reduction of ventilation.


METHODS
This was a double-blind, randomized, placebo-controlled study.


METHODS
University hospital heart failure unit.


METHODS
While receiving placebo (2 months) and a full dosage of carvedilol (4 months), 15 chronic heart failure patients were evaluated by quality-of-life questionnaire, pulmonary function tests, cardiopulmonary exercise tests with constant workload, and a ramp protocol.


RESULTS
Therapy with carvedilol did not affect resting pulmonary function and exercise capacity. However, carvedilol improved the results of the quality-of-life questionnaire, reduced the mean (+/- SD) slope of the minute ventilation (E)/carbon dioxide output (CO(2)) ratio (from 36.4 +/- 8.9 to 31.7 +/- 3.8; p < 0.01) and reduced ventilation at the following times: at peak exercise (from 60 +/- 14 to 48 +/- 15 L/min; p < 0.05); during the intermediate phases of a ramp-protocol exercise; and during the steady-state phase of a constant-workload exercise (from 42 +/- 14 to 34 +/- 13 L/min; p < 0.05, at third min). The end-expiratory pressure for carbon dioxide increased as ventilation decreased. The reduction in the E/CO(2) ratio was correlated with improvement in quality of life (r = 0.603; p < 0.02).


CONCLUSIONS
Improvement in the clinical conditions of heart failure patients treated with carvedilol is associated with reductions in the inappropriately elevated ventilation levels observed during exercise.
Agostoni
Piergiuseppe
P
Centro Cardiologico, Monzino, Istituto di Ricovero e Cura a Carattere Scientifico, Istituto di Cardiologia, Università di Milano, via Parea 4, 20138 Milan, Italy. Agostoni@cardiologicomonzino.it
Guazzi
Marco
M
Bussotti
Maurizio
M
De Vita
Stefano
S
Palermo
Pietro
P
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology* / Q000627:therapeutic use; D002227:Carbazoles / Q000494:pharmacology* / Q000627:therapeutic use; D000077261:Carvedilol; D004311:Double-Blind Method; D015444:Exercise; D006333:Heart Failure / Q000503:physiopathology*; D006801:Humans; D008875:Middle Aged; D011412:Propanolamines / Q000494:pharmacology* / Q000627:therapeutic use; D011788:Quality of Life; D012119:Respiration / Q000187:drug effects*; D011795:Surveys and Questionnaires
D000319:Adrenergic beta-Antagonists; D002227:Carbazoles; D011412:Propanolamines; D000077261:Carvedilol