Lack of improvement in autonomic cardiac tone after sacubitril/valsartan at lower than target doses.

Autonomic regulation plays a role in the progression of heart failure with reduced ejection fraction (HrEF).Twenty-one HFrEF patients, 60.8 ± 13.1 years, receiving angiotensin inhibition, were replaced by angiotensin receptor-neprilysin inhibitor (ARNI). A 24-hour Holter recording was performed before and after 3 months of the maximum tolerated dose of ARNi. We evaluated changes in autonomic tone using heart rate variability (SDNN, rMSSD, pNN50, LF, HF, LF/HF, α1, α2), and heart rate turbulence (TO and TS). ARNI was up-titrated to a maximum daily dose of 190 ± 102 mg, 47.5% of the target dose. ARNI therapy was not associated with any improvement in any of the parameters related with heart rate variability or heart rate turbulence (p > 0.05 for all). ARNI use at lower than target doses did not improve autonomic cardiac tone as evaluated by 24-hour Holter monitoring.