According to WHO estimates, worldwide, 1.28 billion adults between the age of 30-79 years have hypertension. Furthermore, only 1 in 5 people with hypertension have it under control. In approximately 15% of the patients treated for hypertension, optimum blood pressure levels are not achieved even after the addition of 3-4 conventional anti-hypertensive drugs. These patients are diagnosed as resistant hypertensives. Resistant hypertension is associated with an increased risk of cardiovascular death, myocardial infarction, and stroke.

Hypertension is a chronic condition where arterial pressures are persistently elevated, leading to an increase in the pulsatile load on the arteries. This can result in structural and functional alterations in the arterial wall leading to an increase in 'arterial stiffness'.

Arterial stiffness is dependent on the mechanical load (blood pressure) and the material properties of the vessel wall. There is a vicious loop between hypertension and arterial stiffness, where hypertension may lead to alteration in the vascular structure and cause degradation of the elastic components of the vessel wall, and an increase in arterial stiffness can lead to higher blood pressure. An increase in arterial stiffness is associated with higher cardiovascular disease (CVD) risk, and patients with resistant hypertension are at a significantly higher risk of developing CVD. Measurement of carotid-femoral pulse wave velocity (PWV) is considered the gold standard for assessing arterial stiffness and has been recommended as a method to evaluate arterial stiffness as a part of routine care in patients with hypertension. The European Society of Hypertension (ESH) and the working group of the European Society of Cardiology (ESC) recommend its use for the evaluation of cardiovascular risk.

Inclusion Criteria:

• Patients between 18-90 years of age in both sexes, diagnosed with resistant hypertension.
• - Resistance Hypertension defined as -
• Blood pressure at consultation > 140 and/or 90 mmHg and/or 24h-ABPM (Ambulatory Blood Pressure Assessment) and/or in Home blood pressure measurement (HBPM) > 130 and/or 80 mmHg despite taking three or more different classes of antihypertensive drugs at optimal doses, including a diuretic, on the day of screening irrespective of the BP on the day of the visit.
• Any office BP, ABPM or HBPM values in patients taking four or more different classes of antihypertensive drugs at optimal doses, including a diuretic.
• Patients scheduled for arterial stiffness assessment as a part of routine treatment.
• Patients eligible or affiliated with a social security scheme.
• Patients who provide written informed consent for participation.

Exclusion Criteria:

• - Inability to express consent to the study
• Persons subject to a judicial safeguard measure, under guardianship or curatorship.
• Patients with skin lesions (severe eczema, wounds, etc.) on the chest or neck that do not allow the application of the protective skin film on the area of interest; Allergies to the adhesive film.
• Subjects not affiliated with social security or an equivalent scheme.
• Linguistic incapacity or psychic refusal to read the information.
• Diseases carrying out a life -expectancy <1 year according to clinical judgment
• Pregnant women (because of physiological hemodynamic changes in BP and stiffness during pregnancy)
• Arrhythmias: current AC/FA, high degree BAV.
• Persons subject to a period of exclusion for another research
• Foreseen inability to attend scheduled visits