Impact of 6 months of therapy with carvedilol on muscle sympathetic nerve activity in heart failure patients.
BACKGROUND
The long-term effects of carvedilol on muscle sympathetic nerve activity (MSNA) and muscle blood flow at rest and exercise in patients with chronic heart failure (CHF) remain unknown.


RESULTS
Twenty-six patients (New York Heart Association class II-III) were randomized to carvedilol or placebo. Blood pressure, heart rate, MSNA, and forearm vascular resistance (FVR) at rest and during isometric forearm exercise (10% and 30% maximal voluntary contraction) were assessed before and after 6 months. Seven patients did not complete the study. Paired data were obtained in 19 (carvedilol 12, placebo 7). Carvedilol significantly decreased MSNA levels and heart rate at rest (-13 +/- 2 versus 3 +/- 8 bursts/min, P = .0001 and -16 +/- 3 vs -4 +/- 6 bpm, P = .05, respectively) and peak exercise (30% = -20 +/- 5 versus -3 +/- 7 bursts/min, P = 0.05 and -19 +/- 4 versus -4 +/- 6 bpm, P = 0.03, respectively) when compared with placebo. Carvedilol did not change a magnitude of response of MSNA and heart rate during exercise (-10 +/- 3 versus -7 +/- 2 bursts/min, P = 0.7 and 11 +/- 3 versus 6 +/- 1, P = .6, respectively). FVR was unchanged by carvedilol. When MSNA was quantified by burst incidence, the strength of reduction in MSNA was attenuated but still greater than placebo.


CONCLUSIONS
Carvedilol reduces MSNA in patients with CHF. Carvedilol does not reduce FVR at rest or during isometric exercise.
De Matos
Luciana D N J
LD
Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil.
Gardenghi
Giulliano
G
Rondon
Maria Urbana P B
MU
Soufen
Helena N
HN
Tirone
Adriana P
AP
Barretto
Antonio C P
AC
Brum
Patrcia C
PC
Middlekauff
Holly R
HR
Negrão
Carlos E
CE
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects; D002227:Carbazoles / Q000494:pharmacology / Q000627:therapeutic use*; D000077261:Carvedilol; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006333:Heart Failure / Q000188:drug therapy* / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation*; D010543:Peroneal Nerve / Q000503:physiopathology*; D011412:Propanolamines / Q000494:pharmacology / Q000627:therapeutic use*; D014655:Vascular Resistance / Q000187:drug effects
D000319:Adrenergic beta-Antagonists; D002227:Carbazoles; D011412:Propanolamines; D000077261:Carvedilol