Analysis of heart rate variability in hypertensive patients before and after treatment with angiotensin II-converting enzyme inhibitors

Abstract

Objective: To compare heart rate variability in normotensive and hypertensive individuals and to observe the behavior of the autonomic nervous system after treatment with angiotensin II-converting enzyme inhibitors.

Method: The study comprised 286 patients diagnosed with arterial hypertension (AH) for the first time and divided into 4 groups according to diastolic blood pressure (DBP) levels: group A -- DBP<90 mmHg; group B -- DBP 90-99 mmHg; group C -- DBP 100-109 mmHg; group D -- DBP>110 mmHg. Group A (110 healthy individuals) and group C (79 patients with moderate AH) underwent 24-hour Holter-ECG with analysis of heart rate variability in time domain (TD) and frequency domain (FD). The group C patients were treated with ACE inhibitors for 3 months, and, after this period, they underwent a new 24-hour Holter-ECG study for assessing heart rate variability, the values being compared with those of normotensive individuals.

Results: The SDNN and PNN50 parameters (TD), and the LF spectrum (FD) were significantly different in the 2 groups, with clearly reduced values in hypertensive individuals (P<0.05). Group C patients, after treatment with ACE inhibitors, showed a recovery in all variables of heart rate variability, achieving values close to those of normotensive individuals.

Conclusion: Heart rate variability was reduced in hypertensive patients when compared with that in normotensive individuals, indicating a decrease in the baroreceptor reflex. A functional autonomic adjustment after the antihypertensive treatment with ACEI was observed, indicating recovery of parasympathetic tonus.