Administration time-dependent effect of quinapril on heart rate variability and its dependence on hypotensive effec in patients with primary hypertension

Abstract

Background HRV is an indicator of the sympathetic-parasympathetic balance. Decrease in HRV parameters in hypertensive patients was observed, as well as a positive impact of ACEI. The aim of this study was to assess the profile and circadian variability of BP, and to establish dependence between the effect of time-dependent ACEI administration on HRV and its hypotensive effect.
Material and methods Following two-weeks placebo run-in period, 60 patients aged 40.0 ± 15.7 years with mild to moderate essential hypertension received quinapril 10 mg in the morning. After two weeks, in patients with poor BP control the dose was doubled. After next four weeks administration time was changed for evening. Treatment was continued for the next four weeks. At the visits V1, V3, V4 24-hours ECG was performed. Selected parameters of time and frequency domain measures of HRV were analyzed.
Results After morning quinapril administration SBP normalized in 55% patients and DBP in 61,7% of patients, while evening dosage in 75% and 78%, respectively. Most of time domain measures of HRV parameters increased after treatment, but only evening administration caused significant differences in SDNN, SDANN, rMSSD, p50NN and TINN. TP, HF and LF increased during the day and night, but only evening dosage resulted in significant changes of TP and HF, and additionally LF at night. No logical relationships between changes of circadian BP variability and HRV changes after treatment were found.
Conclusions Evening administration of ACEI more than morning dosage increases HRV, and beneficial influence seems to be independent of hipotensive effect.