# 🔧 Resistant HTN & Device Therapy

## 🆕 Formal Device Therapy Integration

The 2025 guidelines formally integrate **renal denervation** into the therapeutic algorithm with Class 2b recommendation, acknowledging modest efficacy (5-10 mmHg office SBP reduction) while recognizing procedural costs and uncertain long-term durability.

## 🎯 Resistant Hypertension Definition

### 📏 Precise Clinical Definition

Blood pressure above goal despite THREE optimally-dosed antihypertensives including a DIURETIC OR controlled BP requiring FOUR or more medications **"Above goal" means which goal?** The 2025 AHA/ACC guideline and the ADA Standards of Care use \<130/80 mmHg. KDIGO 2021 (Blood Pressure in CKD) suggests a target systolic \<120 mmHg when tolerated, using standardized office measurement (grade 2B, driven by the CKD subgroup of SPRINT), and explicitly excludes kidney transplant recipients and patients on dialysis. Much of the gap is measurement technique rather than disagreement about physiology: KDIGO's lower number presumes a standardized or unattended reading, which most routine clinic cuffs do not meet. Which goal you apply changes who counts as resistant.

#### Prevalence

10-15%

of treated hypertensive patients

#### CV Risk

2-3x higher

than controlled hypertension

#### Mortality Risk

50% increase

in cardiovascular events

## 🔍 Systematic Evaluation Protocol

### Step-by-Step Assessment

1

#### Confirm True Resistance with Out-of-Office Monitoring

- **ABPM preferred:** 24-hour monitoring with \<10% reduction from office readings
- **Home monitoring:** 7-day protocol averaging ≥130/80 mmHg
- **White-coat resistance:** Exclude elevated office but normal out-of-office BP
- **Masked uncontrolled HTN:** Normal office but elevated out-of-office BP

2

#### Assess Medication Adherence

- **Pharmacy records:** Review prescription fill patterns and timing
- **Pill counts:** Direct assessment of remaining medications
- **Drug levels:** Serum levels when available and indicated
- **Patient interview:** Direct questioning about barriers to adherence
- **Cost barriers:** Assess financial constraints affecting compliance

3

#### Exclude Secondary Causes

- **Primary aldosteronism:** Universal screening with aldosterone-to-renin ratio
- **Sleep apnea:** STOP-BANG questionnaire, sleep study if indicated
- **Renovascular disease:** Age-appropriate screening (young: FMD, older: atherosclerotic)
- **Pheochromocytoma:** If episodic symptoms or family history
- **Drug-induced HTN:** NSAIDs, decongestants, stimulants, steroids

4

#### Optimize Current Regimen

- **Medication doses:** Ensure maximum tolerated doses of current agents
- **Drug combinations:** Verify synergistic combinations (ACE/ARB + diuretic + CCB)
- **Diuretic adequacy:** Ensure appropriate diuretic type and dose
- **Timing optimization:** Consider bedtime dosing for chronotherapy

5

#### Add Fourth-Line Agents

- **Spironolactone (Class 1):** 25-50 mg daily if eGFR ≥45 mL/min/1.73m²
- **Alternative MRAs:** Eplerenone if spironolactone intolerance
- **Additional agents:** Beta-blockers, alpha-blockers, central agents
- **Monitor closely:** Kidney function and electrolytes

## 💊 Spironolactone: The Fourth-Line Champion

### Class 1 Recommendation: Mineralocorticoid Receptor Antagonism

#### 📊 Efficacy Data (PATHWAY-2)

- **BP reduction:** −8.7 mmHg home systolic vs placebo (95% CI −9.7 to −7.7)
- **Best-of-four ranking:** Spironolactone was the most effective of 4 add-on drugs (vs doxazosin, bisoprolol, placebo) in approximately 58% of patients in crossover
- **Onset:** 4-6 weeks for full effect
- **Source:** Williams B et al. PATHWAY-2. *Lancet* 2015;386(10008):2059-2068. PMID 26414968

#### 💊 Dosing Protocol

- **Initial dose:** 25 mg daily
- **Titration:** Increase to 50 mg daily if tolerated
- **Maximum dose:** 100 mg daily in selected patients
- **Timing:** Morning administration preferred

#### ⚠️ Safety Requirements

- **eGFR requirement:** ≥45 mL/min/1.73m²
- **Baseline K+:** \<5.0 mEq/L
- **Monitoring:** K+ and creatinine at 1, 3, 6 months
- **Discontinue if:** K+ \>5.5 mEq/L or AKI

#### Alternative MRA: Eplerenone

Consider eplerenone 50-100 mg daily if spironolactone causes gynecomastia or breast tenderness. More selective for mineralocorticoid receptors but less potent and more expensive than spironolactone.

## 🔧 Renal Denervation: Class 2b Recommendation

### Device-Based Therapy Integration

Patient selection requires documented adherence, office SBP 140-180 mmHg, eGFR ≥40 mL/min/1.73m², and absence of significant renal artery abnormalities. The Class 1 requirement for multidisciplinary team evaluation ensures appropriate patient selection and alternative treatment optimization.

#### SPYRAL HTN-OFF MED Pivotal

-3.9 mmHg

24-h ambulatory SBP vs sham (95% CrI -6.2 to -1.6); office SBP -6.5 mmHg\
*Bohm M et al. Lancet 2020;395:1444-51, PMID 32234534*

#### SPYRAL HTN-ON MED

-7.4 mmHg

24-h ambulatory SBP vs sham (95% CI -12.5 to -2.3); office SBP -6.8 mmHg\
*Kandzari DE et al. Lancet 2018;391:2346-55, PMID 29803589*

#### RADIANCE HTN-SOLO

-6.3 mmHg

Baseline-adjusted daytime SBP difference (95% CI -9.4 to -3.1)\
*Azizi M et al. Lancet 2018;391:2335-45, PMID 29803590*

#### Response Rate

Modest, individualized

Set realistic expectations: pooled BP reductions are approximately 4-8 mmHg, not 60-70% "responder" rates as previously claimed

### 🎯 Patient Selection Criteria

#### ✅ Inclusion Criteria

- **Confirmed adherence:** Pharmacy records, pill counts, or drug levels
- **Office SBP:** 140-180 mmHg on ≥3 medications
- **eGFR:** ≥40 mL/min/1.73m² with stable kidney function
- **Renal anatomy:** Suitable renal artery anatomy on imaging
- **Age:** 18-80 years (most studies)
- **Life expectancy:** \>1 year
- **Motivation:** Willing to continue medications post-procedure

#### ❌ Exclusion Criteria

- **Renal artery stenosis:** \>30% stenosis
- **Renal artery anatomy:** \<4 mm diameter or \<20 mm length
- **Previous renal intervention:** Stenting or surgery
- **Type 1 diabetes:** With nephropathy
- **Secondary hypertension:** Untreated identifiable causes
- **Pregnancy:** Current or planned
- **Severe kidney disease:** eGFR \<40 mL/min/1.73m²

#### 🤔 Special Considerations

- **Age \>65:** Enhanced sympathetic activity may predict better response
- **Diabetes:** Type 2 diabetes not an exclusion if no nephropathy
- **Heart failure:** May benefit from sympathetic denervation
- **Chronic kidney disease:** Careful risk-benefit assessment
- **Cost considerations:** Insurance coverage variable
- **Center experience:** Procedure volume and expertise matter

## 🏥 Multidisciplinary Team Approach

### Class 1 Requirement: Team-Based Evaluation

#### 👨‍⚕️ Core Team Members

- **Interventional cardiologist:** Procedure performance and technique
- **Hypertension specialist:** Medical optimization and patient selection
- **Clinical pharmacist:** Medication reconciliation and adherence
- **Nurse coordinator:** Patient education and follow-up coordination

#### 📋 Team Responsibilities

- **Pre-procedure:** Confirm medical optimization and adherence
- **Patient selection:** Multidisciplinary consensus on candidacy
- **Shared decision-making:** Detailed risk-benefit discussion
- **Post-procedure:** Long-term follow-up and medication management

#### ⚖️ Decision Factors

- **Response prediction:** 30-40% non-response rate
- **Durability concerns:** Long-term efficacy uncertain
- **Cost-effectiveness:** High upfront costs vs medication savings
- **Patient preferences:** Individual values and goals

## 🧮 Resistant HTN Risk Calculator

### Treatment Strategy Optimizer

Current medications count: Blood pressure control: eGFR (mL/min/1.73m²): 75 Patient factors: Documented medication adherence Secondary causes excluded Suitable renal artery anatomy

#### Treatment Recommendation

Based on current inputs, treatment recommendations will appear here.

##### Next Steps:

Assessment pending

##### Device Therapy Consideration:

Assessment pending

### 🎯 Key Management Principles

#### 🔍 Systematic Evaluation

Confirm true resistance with out-of-office monitoring, assess adherence, and exclude secondary causes before considering advanced interventions.

#### 💊 Spironolactone First

Class 1 recommendation for spironolactone as fourth-line agent — PATHWAY-2 (Williams, *Lancet* 2015, PMID 26414968) showed −8.7 mmHg additional home systolic vs placebo, and spironolactone ranked best of 4 add-on drugs in approximately 58% of patients in crossover.

#### 🔧 Device Therapy Selection

Renal denervation Class 2b recommendation requires careful patient selection, multidisciplinary evaluation, and realistic expectation setting for modest BP reductions.

## 📚 Sources

1.  **Williams B, MacDonald TM, Morant S, et al; British Hypertension Society's PATHWAY Studies Group.** Spironolactone versus placebo, bisoprolol, and doxazosin to determine the optimal treatment for drug-resistant hypertension (PATHWAY-2). *Lancet.* 2015;386(10008):2059-2068. [PMID: 26414968](https://pubmed.ncbi.nlm.nih.gov/26414968/). \[Source for: PATHWAY-2 home SBP reduction approximately 8.7 mmHg vs placebo; spironolactone superior to bisoprolol and doxazosin as fourth-line agent in resistant HTN. The earlier "20-25 mmHg additional SBP reduction" claim was approximately 3× inflated.\]
2.  **Bhatt DL, Kandzari DE, O'Neill WW, et al; SYMPLICITY HTN-3 Investigators.** A controlled trial of renal denervation for resistant hypertension. *N Engl J Med.* 2014;370(15):1393-1401. [PMID: 24678939](https://pubmed.ncbi.nlm.nih.gov/24678939/). \[Source for: original sham-controlled RDN trial — negative result, prompted reassessment of methodology.\]
3.  **Böhm M, Kario K, Kandzari DE, et al; SPYRAL HTN-OFF MED Pivotal Investigators.** Efficacy of catheter-based renal denervation in the absence of antihypertensive medications (SPYRAL HTN-OFF MED Pivotal). *Lancet.* 2020;395(10234):1444-1451. [PMID: 32234534](https://pubmed.ncbi.nlm.nih.gov/32234534/). \[Source for: SPYRAL OFF-MED demonstrated approximately 4-9 mmHg reduction in 24h ABPM SBP and office SBP at 3 months without medications; positive sham-controlled trial.\]
4.  **Kandzari DE, Böhm M, Mahfoud F, et al; SPYRAL HTN-ON MED Trial Investigators.** Effect of renal denervation on blood pressure in the presence of antihypertensive drugs (SPYRAL HTN-ON MED). *Lancet.* 2018;391(10137):2346-2355. [PMID: 29803589](https://pubmed.ncbi.nlm.nih.gov/29803589/). \[Source for: SPYRAL ON-MED — 24h ABPM SBP reduction approximately 7 mmHg vs sham at 6 months in patients on background HTN medications.\]
5.  **Azizi M, Schmieder RE, Mahfoud F, et al; RADIANCE-HTN Investigators.** Endovascular ultrasound renal denervation to treat hypertension (RADIANCE-HTN SOLO). *Lancet.* 2018;391(10137):2335-2345. [PMID: 29803590](https://pubmed.ncbi.nlm.nih.gov/29803590/). \[Source for: RADIANCE-HTN SOLO ultrasound RDN approximately 6.3 mmHg ABPM SBP reduction vs sham at 2 months.\]
6.  **Whelton PK, Carey RM, Aronow WS, et al.** 2017 ACC/AHA Guideline for High Blood Pressure in Adults. *Hypertension.* 2018;71(6):e13-e115. [PMID: 29133356](https://pubmed.ncbi.nlm.nih.gov/29133356/). \[Source for: resistant HTN definition (≥3 medications including diuretic, BP not at goal); evaluation algorithm.\]
7.  **Carey RM, Calhoun DA, Bakris GL, et al; American Heart Association.** Resistant Hypertension: Detection, Evaluation, and Management. *Hypertension.* 2018;72(5):e53-e90. [PMID: 30354828](https://pubmed.ncbi.nlm.nih.gov/30354828/). \[Source for: AHA scientific statement on resistant HTN; secondary causes screening; pharmacotherapy sequence.\]
8.  **Brown C, Clark D, Jones DW.** Updates in the 2025 AHA/ACC Hypertension Guideline. *Curr Hypertens Rep.* 2026;28(1). [PMID: 41843050](https://pubmed.ncbi.nlm.nih.gov/41843050/). \[Source for: 2025 AHA/ACC update — renal denervation introduced as adjunctive option for select resistant-HTN patients; expanded primary aldosteronism screening for stage 2 / resistant HTN.\]

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