1031–34 Differential Effect of Bisoprolol on Heart Rate Variability According to Heart Rate in Patients with Heart Failure

Patients with congestive heart failure (CHF) have reduced heart rate variability (HRV). Beta-blockers (BB) therapy could improve HRV in CHF. However, HRV is influenced by heart rate. The aim of our study was to assess the effect of BB on heart rate adjusted-HRV in 52 patients from the randomized, double-blind, placebo-controlled CIBIS trial (Cardiac Insufficiency Bisoprolol Study). After progressive increase, Bisoprolol was 5 mg once a day. Holter tapes were recorded at baseline and after 2 months of therapy. To assess HRV at given heart rates, we developed a geometrical analysis of scatterplots (SCP). SCP display beat-ta-beat HRV by plotting each RR against the preceding RR interval. SCP heigth, a measure of short term HRV, was measured at the 10th, 25th, 50th, 75th and 90th percentiles of the total RR dispersion (figure). The 10th percentile represents the fastest hearts rates, whereas the 90th represents the slowest heart rates. There was no significant difference in baseline SCP measurements. Results of BB therapy on SCP heights are as follow (mean±SD):PlaceboBisoprololp10th perc (ms)58±1864±30NS25th perc (ms)95±35101±35NS50th perc (ms)133±43152±370.0275th perc (ms)134±53171±530.00490th perc (ms)120±12139±460.05In conclusion, HRV is not improved at higher heart rates. On the contrary, these results indicate that low dose Bisoprolol improves short term HRV at lower heart rates in CHF