Resistant or refractory hypertension: it is not just the of number of drugs

In accordance with the 2018 European ESC-ESH (1), 2020 International Society Hypertension (2) and 2017 American College of Cardiology/American Heart Association (3) guidelines , resistant hypertension is classically defined as a clinical feature characterized by blood pressure values of at least 140/90 or at least 130/80 mmHg, with triple full dose pharmacological therapy, including a diuretic, combined with lifestyle modifications. Resistant hypertension must be distinguished from difficult-to-control hypertension which is much more common (4,5). Very often it is impossible to identify a sole responsible factor of failure to respond to pharmacological therapy. It is thought that the majority of patients with resistant hypertension have underlying multifactorial contributing factors comprising both genetic and environmental components. For a case of resistant hypertension, a clinician must evaluate all possible causes of true resistant and pseudo-resistant hypertension. The medical history is a pivotal point of the diagnostic work-up. This should focus on the severity of hypertension, adherence to treatment, use of hypertensive substances, sleeping habits (daytime sleep, obstructive sleep apnea), any referable symptoms to secondary hypertension and known history of cardiovascular and renal diseases. Factors associated with pseudo-resistant hypertension must therefore be ruled out. Inadequate antihypertensive treatment, lack of adherence to prescribed therapy, white-coat resistant hypertension and poor blood pressure measuring techniques are the main causes of pseudo-resistant hypertension. Once true resistant hypertension has been diagnosed, patients should be evaluated for conditions associated with resistance. If resistant hypertension is caused by excessive salt intake, alcohol abuse, obesity, or use of certain classes of drugs, behavioural changes may be sufficient to achieve target blood pressure. Secondary causes of hypertension are frequently diagnosed in patients with resistant hypertension: renovascular disease, primary aldosteronism and obstructive sleep apnea are the most common (1,6).