Definition & Diagnosis - The Pressure Cooker
-
Definition: Uncontrolled blood pressure (BP) despite ≥3 antihypertensive drugs from different classes, including a diuretic, at optimal doses.
- Also includes patients whose BP is controlled but require ≥4 medications.
-
Diagnostic Confirmation:
- Step 1: Exclude Pseudoresistance
- Verify accurate BP measurement technique.
- Assess for medication non-adherence.
- Rule out "white coat" effect with Ambulatory (ABPM) or Home BP Monitoring (HBPM).
- Step 2: Identify Contributing Factors
- Lifestyle: High salt diet, obesity, alcohol.
- Interfering substances: NSAIDs, sympathomimetics.
- Step 1: Exclude Pseudoresistance

⭐ The most common cause of apparent resistant hypertension is poor medication adherence.
Secondary Causes & Workup - Unmasking the Villain
- Common Culprits: Renal parenchymal disease, Renal Artery Stenosis (RAS), Primary Aldosteronism, Obstructive Sleep Apnea (OSA), Pheochromocytoma/Paraganglioma, Cushing's syndrome.
- Clinical Clues:
- RAS: Abdominal bruit, flash pulmonary edema, significant ↑SCr after starting ACEi/ARB.
- Primary Aldosteronism: Stubborn hypokalemia, metabolic alkalosis.
- Pheochromocytoma: Episodic palpitations, headache, sweating (PHEochromocytoma).
- OSA: Snoring, daytime sleepiness, obesity.

⭐ In primary aldosteronism, the initial screening test is the Aldosterone-to-Renin Ratio (ARR). A ratio > 20 with a plasma aldosterone concentration (PAC) > 15 ng/dL strongly suggests the diagnosis. Patients should hold diuretics and mineralocorticoid receptor antagonists before testing.
Pharmacologic Algorithm - The Add-On Game
First, ensure adherence and maximize doses of a 3-drug regimen: ACEi/ARB + CCB + a long-acting thiazide diuretic (e.g., chlorthalidone).
- 4th Line: MRAs are preferred.
- Spironolactone: 25-50 mg daily. Watch for ↑K+ and gynecomastia.
- Eplerenone: Fewer hormonal side effects.
- 5th/6th Line: Use if MRA is contraindicated (e.g., GFR <30, K+ >5.0).
- Beta-blockers: Best with compelling indications (HFrEF, IHD).
- Direct vasodilators: Hydralazine, Minoxidil.
⭐ The PATHWAY-2 trial showed spironolactone was the most effective 4th-line agent for lowering BP in resistant hypertension.

- Resistant hypertension is uncontrolled BP despite ≥3 drugs (including a diuretic) or controlled on ≥4 drugs.
- Always rule out secondary causes, especially primary aldosteronism (check renin & aldosterone).
- Exclude pseudoresistance from non-adherence or white coat effect with ambulatory monitoring.
- The preferred fourth-line agent is a mineralocorticoid receptor antagonist (MRA) like spironolactone.
- Watch for hyperkalemia and gynecomastia with spironolactone; eplerenone is an alternative.
Continue reading on Oncourse
Sign up for free to access the full lesson, plus unlimited questions, flashcards, AI-powered notes, and more.
CONTINUE READING — FREEor get the app