Effect of beta-blockade on autonomic modulation of heart rate and neurohormonal profile in decompensated heart failure
Abstract
One of the putative mechanisms for the salutary effects of beta-blockers in patients with congestive heart failure (CHF) is their ability to improve autonomic dysfunction. However, patients with profound neurohumoral abnormalities derive little survival benefit from beta-blockers. The purpose of the current study was to evaluate the effect of beta-blockers on heart rate variability (HRV) in decompensated CHF. Time and frequency domain HRV indices were obtained from 24-hour Holter recordings and compared to assess the role of beta-blockade in 199 patients (mean age 60 +/- 14 years) with decompensated CHF. Neurohormonal differences were assessed by measuring norepinephrine, endothelin-1, tumor necrosis factor-alpha, and interleukin-6 in a subset of 64 patients. All HRV indices were markedly suppressed but were substantially higher in patients who were on beta-blockers. Time domain measures of parasympathetic cardiac activity, the percentage of R-R intervals with > 50 ms variation (4.9 +/- 0.6 vs 7.7 +/- 1.2%, P = 0.006) and the square root of mean squared differences of successive R-R intervals (22.7 +/- 2.0 vs 31.6 +/- 4.1 ms, P = 0.004), were higher in the beta-blocker group. Spectral analysis revealed that the total power and ...Continue Reading
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