This single-center, cross-sectional observational study examines the relationship between adherence to antihypertensive therapy - verified objectively by therapeutic drug monitoring (TDM) - and heart rate variability (HRV) in patients with resistant hypertension. Patients are recruited opportunistically, in a nurse-led manner, in a one-day-care cardiology unit, and undergo a single examination: a short-term HRV recording (Polar H10), a single blood draw for antihypertensive drug levels, office blood pressure, and self-completed questionnaires. There is no follow-up.
Non-adherence to antihypertensive medication is a major cause of apparently resistant hypertension and confounds interpretation of autonomic measures. HRV is a non-invasive index of autonomic cardiac regulation and is systematically influenced by antihypertensive drugs. The study tests whether TDM-verified intake of antihypertensives is reflected in HRV parameters, and whether HRV can serve as a complementary marker of adherence. Adherence is determined by TDM (the objective gold standard); a self-report questionnaire (MARS-CZ) is collected as a secondary, descriptive measure. HRV is recorded for 10-15 minutes seated, before sedation and before heparin/contrast; the blood sample is drawn before heparin/contrast, with the time of last dose recorded. Time-domain (SDNN, RMSSD, pNN50) and frequency-domain (LF, HF, LF/HF) HRV parameters are analysed. Approximately 100-200 patients are planned for enrolment. It does not interfere with the patient's planned cardiac procedure; the one-day-care unit is the recruitment venue only.
Study Type
OBSERVATIONAL
Enrollment
150
Short-term (10-15 min) seated HRV; time-domain (SDNN, RMSSD, pNN50) and frequency-domain (LF, HF, LF/HF) parameters.
Single blood draw measuring antihypertensive drug levels; defines adherent vs non-adherent status.
Self-completed instruments assessing medication adherence, mood, quality of life, and physical activity.
Nemocnice AGEL Třinec-Podlesí a.s.
Třinec, Moravian-Silesian Region, Czechia
Heart rate variability parameters by TDM-defined adherence
Time-domain (SDNN, RMSSD, pNN50) and frequency-domain (LF, HF, LF/HF ratio) HRV parameters from a short-term seated recording, compared between TDM-adherent and TDM-non-adherent patients.
Time frame: At the single study visit (Day 1)
Heart rate variability in relation to office blood-pressure control
Association between HRV parameters and office blood pressure measured seated immediately before the HRV recording.
Time frame: At the single study visit (Day 1)
Questionnaire scores in relation to adherence and HRV
Scores of MARS-CZ (adherence), PHQ-9 (mood), SF-36 (quality of life), and IPAQ (physical activity) examined against TDM-defined adherence and HRV parameters.
Time frame: At the single study visit (Day 1)
Prevalence of non-adherence by therapeutic drug monitoring
Proportion of patients classified as non-adherent to antihypertensive therapy based on TDM (absent or subtherapeutic drug levels).
Time frame: At the single study visit (Day 1)
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