The effect of continuous positive airway pressure on heart rate variability during the night in patients with chronic heart failure and central sleep apnoea

Summary Continuous positive airway pressure ( CPAP ) improves autonomic activity in patients with chronic heart failure ( CHF ) and central sleep apnoea ( CSA ), but its effect on heart rate variability ( HRV ) during therapy has not been reported. We hypothesized that CPAP may decrease HRV , despite its beneficial effects on sympathetic overactivation, due to the expected stabilization of breathing. Sixty‐seven CHF patients underwent polysomnography ( PSG ). Ten of them presented with CSA (age 66.1±8.5 years, apnoea‐hypopnea index [ AHI ]=57.6±23.3, central AHI [ cAHI ]=41.6±24.6 [mean± SD ]) and were subjected to a second PSG with manual CPAP titration. Beat‐to‐beat heart intervals for a 6‐hour period of sleep were extracted from each recording and HRV was analysed. CPAP significantly reduced AHI ( AHI =23.1±18.3 P =.004). Standard deviation of normal‐normal interbeat interval ( SDNN ) (61.5±29.0 vs 49.5±19.3 ms, P =.021), root mean square of successive differences ( RMSSD ) (21.8±9.2 vs 16.4±7.1 ms, P =.042), total power (ln TP =7.8±1.1 vs 7.4±0.8 ms 2 , P =.037), low frequency power (ln LF =5.5±1.5 vs 5.0±1.4 ms 2 , P =.003) and high frequency power (ln HF =4.6±1.0 vs 4.0±1.0 ms 2 , P =.024) were decreased. There was a strong correlation between the decrease in AHI and the decrease in ln HF (Spearman's ρ=.782). CPAP leads to a decrease in spectral and time domain parameters of HRV during therapy in CHF patients with CSA . These changes are best explained by the effect which CPAP ‐influenced breathing pattern and lowered AHI exert on HRV .