Does carvedilol improve parasympathetic nervous system activity in patients with congestive heart failure?
Long-term carvedilol therapy substantially increases parasympathetic modulation of RR intervals in patients with chronic congestive heart failure.
To determine the effect of beta blockade on parasympathetic nervous system activity, we assessed RR variability during 24-hour Holter monitoring in 10 patients with congestive heart failure before and after 3 to 4 months of treatment with the beta blocker carvedilol. High-frequency power increased from 26 to 64 ms2, root-mean-square of successive differences in RR interval increased from 14.3 to 23.7 ms2, and percentage of absolute differences >50 ms between successive normal RR intervals increased from 0.8% to 4.7%, all p <0.01, indicating a substantial increase in parasympathetic modulation of RR intervals.
Goldsmith et al. (Wed,) studied this question.