RAS Peptide Profiles in Patients With Treatment-resistant Arterial Hypertension

Inclusion criteria * Office blood pressure ≥ 140/90 mmHg and mean 24 hour blood pressure \>130/80 mmHg on average, or \>135/85 mmHg during the day, or \> 120/70 mmHg during the night, despite concurrent use of 3 antihypertensive agents at optimal doses, including one diuretic OR * Office blood pressure and 24 hour mean blood pressure controlled with four or more medications * Age ≥ 18 years * Ability to understand research procedures and to provide written informed consent Exclusion criteria * Known secondary arterial hypertension at time of inclusion or diagnosis of secondary hypertension after study inclusion during routine work-up of treatment resistant hypertension * Known obstructive sleep apnea at time of inclusion * History of, or clinically relevant or uncontrolled cardiovascular disease (other than arterial hypertension), namely myocardial infarction within last 3 months or valvular heart disease with clinically relevant reflux or heart failure * Any circumstances or conditions, which, in the opinion of the investigator, may affect full participation in the research project or compliance with the research plan.