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Chronotropic incompetence, beta‐blockers, and functional capacity in advanced congestive heart failure: Time to pace?
Author(s) -
Jorde Ulrich P.,
Vittorio Timothy J.,
Kasper Michael E.,
Arezzi Emma,
Colombo Paolo C.,
Goldsmith Rochelle L.,
Ahuja Kartikya,
Tseng ChiHong,
Haas Francois,
Hirsh David S.
Publication year - 2008
Publication title -
european journal of heart failure
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.149
H-Index - 133
eISSN - 1879-0844
pISSN - 1388-9842
DOI - 10.1016/j.ejheart.2007.11.006
Subject(s) - medicine , chronotropic , heart failure , cardiology , heart rate , beta blocker , blood pressure
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 and results: 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 >20.0ml/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±1451pg/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.