Chronotropic incompetence, beta-blockers, and functional capacity in advanced congestive heart failure: time to pace?
Eur J Heart Fail
; 10(1): 96-101, 2008 Jan.
Article
en En
| MEDLINE
| ID: mdl-18096432
ABSTRACT
BACKGROUND:
Chronotropic incompetence (CI) is often seen in subjects with chronic congestive heart failure (CHF). The prevalence of CI, its mechanisms and association with beta-blocker use as well as exercise capacity have not been clearly defined. METHODS ANDRESULTS:
Cardiopulmonary exercise tolerance testing data for 278 consecutive patients with systolic CHF was analyzed. CI, defined as the inability to reach 80% of maximally predicted heart rate was present in 128 of 278 subjects (46%). The prevalence of CI was highest in those with most impaired exercise capacity (72, 48, and 24% for subjects with a VO(2) of <14.0, 14.0-20.0, and >20.0 ml/kg/min respectively; p=0.001). While subjects with CI had lower peak exercise heart rate (114 vs. 152 bpm), and lower peak VO(2) (15.4 vs. 19.9 ml/kg/min), they were equally likely to be on chronic beta-blocker therapy (74% vs. 71%; p=0.51). Heart rate and norepinephrine (NE) levels were measured during exercise in a separate cohort of 24 subjects with CHF. There was no difference in beta-blocker dose between subjects with and without CI, however, exercise induced NE release and Chronotropic Responsiveness Index, a measure of post-synaptic beta-receptor sensitivity to NE, were lower in subjects with CI (1687+/-911 vs. 2593+/-1451 pg/ml p=0.08; CRI 12.7+/-5.7 vs. 22.1+/-4.7, p=0.002).CONCLUSIONS:
CI occurs in >70% of subjects with advanced systolic CHF irrespective of beta-blocker use and is associated with a trend toward impaired NE release, post-synaptic beta-receptor desensitization and reduced exercise capacity.
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Banco de datos:
MEDLINE
Asunto principal:
Consumo de Oxígeno
/
Ejercicio Físico
/
Tolerancia al Ejercicio
/
Antagonistas Adrenérgicos beta
/
Insuficiencia Cardíaca
/
Frecuencia Cardíaca
Tipo de estudio:
Prognostic_studies
/
Risk_factors_studies
Límite:
Female
/
Humans
/
Male
/
Middle aged
Idioma:
En
Revista:
Eur J Heart Fail
Asunto de la revista:
CARDIOLOGIA
Año:
2008
Tipo del documento:
Article
País de afiliación:
Estados Unidos