Meeting Criteria for Resistant Hypertension
BP remains above target despite three well-dosed drug classes, one a diuretic.
- ≥3 classes: Definition threshold (includes a diuretic)
- ~15–20%: Prevalence in treated HTN (of treated adults)
- Yes: Includes controlled-on-4+ (also counts as resistant)
- Exclude pseudo: First step required (before secondary workup)
What counts as resistant hypertension
Uncontrolled BP on three optimized classes, or controlled on four or more, defines resistant hypertension.
Why the definition matters clinically
Meeting criteria triggers a structured workup rather than simply adding another drug.
Excluding Pseudo-Resistance Before Secondary Workup
Adherence gaps and white-coat effect mimic true treatment resistance often.
- ~30–50%: Non-adherence rate (in apparent resistance)
- ~30%: White-coat contribution (of apparent cases)
- ABPM / HBPM: Confirmation method (out-of-office readings)
- Common: Cuff-size errors (inflate readings falsely)
Confirming medication adherence
Pill counts, pharmacy refill data, or drug-level testing verify true adherence.
Correcting measurement technique
Proper cuff size, rest period, and ambulatory monitoring exclude white-coat effect.
Systematic Secondary-Cause Screening
Three parallel tests screen renal, adrenal, and sleep-related causes.
- Duplex / CTA: Renal artery test (stenosis detection)
- ARR: Aldosterone screen (aldosterone-renin ratio)
- Polysomnography: Sleep apnea test (or home sleep study)
- ~5–20%: Secondary-cause yield (of resistant cases)
Renal artery stenosis screening
Duplex ultrasound or CT angiography assesses renal artery narrowing directly.
Primary hyperaldosteronism screening
Elevated aldosterone-renin ratio prompts confirmatory suppression testing next.
Obstructive sleep apnea screening
Sleep study quantifies apnea-hypopnea index tied to resistant BP.
Interpreting Screening Results
Positive findings confirm a cause; negative results support essential hypertension.
- Confirmatory test: Positive result path (before treatment)
- True resistant HTN: All-negative path (essential etiology)
- Possible: Multiple positives (causes can coexist)
- Common: Specialist referral (for confirmed causes)
Confirming a positive screen
Each positive screen is confirmed with a dedicated diagnostic test before acting.
Ruling out all secondary causes
Three negative screens support a diagnosis of true resistant essential hypertension.
Targeted Treatment or Optimized Therapy
Confirmed causes get targeted therapy; otherwise the regimen is intensified.
- Revascularization: Renal stenosis treatment (angioplasty/stent)
- MRA therapy: Hyperaldosteronism treatment (spironolactone/eplerenone)
- CPAP: Sleep apnea treatment (often lowers BP)
- Optimize regimen: No cause found (add 4th-line agent)
Targeted treatment when a cause is found
Revascularization, MRA therapy, or CPAP directly addresses the identified cause.
Optimizing therapy for true essential resistance
Add spironolactone or another fourth-line class and reassess response over time.
Placeholder highlight — spironolactone is the preferred fourth-line add-on agent.