What is the definition of resistant hypertension?

Definition of Resistant Hypertension

Resistant hypertension is defined as blood pressure that remains above goal despite the concurrent use of 3 antihypertensive agents of different classes, with one ideally being a diuretic, all prescribed at optimal doses. 1 This definition also includes patients whose blood pressure is controlled but requires 4 or more medications to achieve control.

Key Components of the Definition

• Uncontrolled BP: Blood pressure ≥140/90 mmHg despite appropriate therapy
• Medication Requirements:
  • Three or more antihypertensive medications from different classes
  • One of the medications should be a diuretic
  • All medications at optimal or maximally tolerated doses
• Controlled Resistant Hypertension: Patients requiring 4 or more medications to achieve BP control are also considered to have resistant hypertension 1

Exclusions Before Diagnosing True Resistant Hypertension

Before confirming a diagnosis of resistant hypertension, several factors must be ruled out:

• Pseudoresistance:
  • Poor medication adherence
  • Improper BP measurement technique
  • White coat hypertension (elevated BP in clinic but controlled at home)
• Secondary causes of hypertension 2:
  • Obstructive sleep apnea
  • Primary aldosteronism
  • Chronic kidney disease
  • Renal artery stenosis
  • Pheochromocytoma
  • Cushing's syndrome
  • Thyroid disorders

Confirmation of Diagnosis

To properly confirm resistant hypertension:

1. Verify BP measurements with out-of-office readings (home BP monitoring or ambulatory BP monitoring)
2. Assess medication adherence thoroughly
3. Evaluate for interfering substances (especially NSAIDs)
4. Screen for secondary causes when clinically indicated 1, 2

Distinguishing from Refractory Hypertension

It's important to distinguish resistant hypertension from refractory hypertension, which is defined as:

• Uncontrolled BP despite the use of ≥5 antihypertensive agents of different classes
• Including a long-acting thiazide-like diuretic and a mineralocorticoid receptor antagonist 3

Clinical Implications

Resistant hypertension affects approximately 5% of the hypertensive population and is associated with increased cardiovascular morbidity and mortality 4. Patients with resistant hypertension typically have a higher prevalence of diabetes mellitus and elevated LDL-cholesterol levels compared to those with controlled hypertension 5.

The definition is designed to identify patients who:

1. May have reversible causes of hypertension
2. Would benefit from special diagnostic and therapeutic considerations
3. Are at higher risk for cardiovascular events 1

Understanding this definition is crucial for appropriate management, which typically involves lifestyle modifications, optimization of current medications, sequential addition of other drug classes, and consideration of mineralocorticoid receptor antagonists as fourth-line therapy 1, 2.