Cardiovascular

Resistant hypertension: evaluation and adjunctive therapy

Clinical Overview and When to Suspect Resistant Hypertension

— Pseudoresistance (poor adherence, white-coat effect, inadequate dosing, wrong drug class combo)

— Inaccurate measurement (wrong cuff size, lack of rest, talking during measurement, arm unsupported)

— Drug/substance interference (NSAIDs, OCPs, decongestants, stimulants, licorice, cocaine, VEGF inhibitors, calcineurin inhibitors, EPO, chronic steroids)

— Patient on HCTZ 25 + lisinopril 40 + amlodipine 10 with home BP 145/92

— Long-standing HTN with target-organ damage (LVH, CKD, retinopathy) out of proportion to control

— Abrupt loss of control in a previously well-managed patient → think secondary cause or new offending agent

— Young (<30) or older (>65) onset of severe HTN

Board pearl: The diuretic in the 3-drug regimen must be a long-acting thiazide-type (chlorthalidone or indapamide), not HCTZ — switching HCTZ → chlorthalidone alone resolves a meaningful fraction of "resistant" cases because of chlorthalidone's longer half-life (~40h) and stronger 24-hour BP effect.

Step 3 management: Before labeling any patient resistant, confirm with out-of-office BP (ABPM preferred, home BP acceptable), verify adherence (pill counts, pharmacy refill data, witnessed dosing), and review the full med/supplement list including OTC NSAIDs and herbals.

Definition (AHA 2018): office BP above goal (≥130/80 mmHg) despite 3 antihypertensives at maximally tolerated doses, including a long-acting thiazide-type diuretic, an ACEi/ARB, and a CCB — OR BP controlled but requiring ≥4 agents.

True resistant HTN requires exclusion of:

Prevalence: ~10–20% of treated hypertensives meet criteria; apparent resistant HTN is higher because most cases unmask as pseudoresistance after ABPM and adherence checks.

When to suspect on Step 3:

Risk markers: Black race, obesity, OSA, CKD, diabetes, high dietary sodium, older age, female sex.

Presentation Patterns and Key History

— Missed doses, cost barriers, pill burden, side effects (cough on ACEi, edema on CCB, ED on β-blocker)

— Use of NSAIDs (chronic back pain, OA), decongestants (pseudoephedrine, phenylephrine), OCPs, stimulants (ADHD meds, cocaine, amphetamines), licorice, energy drinks, anabolic steroids, VEGF inhibitors (bevacizumab), calcineurin inhibitors (cyclosporine, tacrolimus), EPO

— Dietary sodium intake (>3 g/day) and alcohol (>2 drinks/day men, >1 women)

— OSA: snoring, witnessed apneas, daytime somnolence, nocturia, obesity, large neck circumference, morning headaches

— Primary aldosteronism: muscle weakness, cramps, polyuria, hypokalemia (often normokalemic!), family history

— Renovascular: flash pulmonary edema, abrupt loss of control, rise in Cr ≥30% after ACEi/ARB, smoking, peripheral vascular disease, young woman (FMD)

— Pheochromocytoma: episodic headache + palpitations + sweating, orthostatic spells, panic-like episodes

— Cushing: weight gain, striae, proximal weakness, glucose intolerance

— Coarctation: young patient, leg claudication, differential arm/leg BP

— CKD: known kidney disease, edema, proteinuria

Key distinction: Apparent resistant HTN includes white-coat effect and non-adherence; true resistant HTN persists after ABPM confirmation plus documented adherence. Roughly 30–50% of apparent cases resolve with this filtering — a Step 3 favorite.

Board pearl: New-onset uncontrolled HTN in an elderly smoker with flash pulmonary edema and a bruit = bilateral atherosclerotic renal artery stenosis until proven otherwise.

Typical stem: middle-aged or older adult, often Black or obese, with HTN for years, now on 3+ agents including a diuretic, with persistently elevated office or home readings.

Targeted history — adherence and pseudoresistance:

Clues to secondary causes:

Lifestyle: physical inactivity, weight trajectory, sleep duration <6h.

Physical Exam Findings and Hemodynamic Assessment

— Patient seated, back supported, feet flat, 5 min rest, no talking, no caffeine/nicotine/exercise within 30 min

— Cuff bladder = 80% of arm circumference; small cuff on a large arm falsely elevates BP by 10–40 mmHg

— Arm at heart level; unsupported arm raises reading

— Measure both arms at first visit; >15 mmHg interarm difference suggests subclavian stenosis/PAD

— Take ≥2 readings, ≥1 min apart, average them

Hemodynamic phenotyping when available:

— Volume-overloaded phenotype (elderly, CKD, Black patients, edema) → benefits most from diuretic optimization and MRA

— High sympathetic tone phenotype (tachycardia, anxiety, younger) → β-blocker or central agent

— Vasoconstrictive phenotype → CCB or vasodilator

Step 3 management: Always perform orthostatic vitals — significant orthostatic drop limits how aggressively you can titrate and points toward autonomic dysfunction, volume depletion, or α-blocker effect.

Board pearl: Diminished or delayed femoral pulses with upper-extremity HTN in a young adult = aortic coarctation — order TTE and CTA, not just more antihypertensives.

Accurate BP measurement is itself part of the exam — Step 3 frequently rewards recognizing technique errors:

General: BMI, central obesity, moon facies/buffalo hump/striae (Cushing), Marfanoid features.

HEENT: AV nicking, hemorrhages, exudates, papilledema (hypertensive retinopathy grading), thyromegaly.

Neck: carotid bruits, JVD.

Cardiac: sustained PMI/LV heave (LVH), S4 gallop, murmurs (AR can mimic widened pulse pressure).

Abdomen: abdominal/flank bruit (renovascular HTN), pulsatile mass (AAA), enlarged kidneys (PKD).

Extremities: radial-femoral delay and lower-extremity hypotension (coarctation), diminished peripheral pulses (PAD), edema (CKD, CHF, CCB side effect).

Skin: café-au-lait, neurofibromas, axillary freckling (NF1 → pheochromocytoma).

Neuro: focal deficits from prior strokes.

Diagnostic Workup — Initial Labs, Imaging, ECG, Biomarkers

— 24-hour ABPM is the gold standard; HBPM acceptable if patient performs validated technique (twice daily, AM and PM, 7 days, discard day 1, average remaining)

— Diagnostic thresholds for out-of-office: daytime ABPM ≥130/80, 24-h ≥125/75, HBPM average ≥130/80

— BMP (Na, K, Cl, HCO3, BUN, Cr, eGFR) — hypokalemic alkalosis → aldosteronism

— Fasting glucose/HbA1c, lipid panel — cardiovascular risk

— TSH — both hyper- and hypothyroidism worsen BP control

— Urinalysis with urine albumin-to-creatinine ratio — proteinuria/CKD

— Calcium — hyperparathyroidism association

— Plasma aldosterone-to-renin ratio (ARR) as initial screen

— Positive: aldosterone >10 ng/dL AND ARR >20 (some use >30)

— Correct hypokalemia first; ideally discontinue MRAs for 4–6 weeks; ACEi/ARB, β-blockers, and most other agents can usually be continued, but interpret with caution

Board pearl: Screen every resistant HTN patient for primary aldosteronism — it is far more common (~20%) than historically taught, and normokalemia does not exclude it.

Step 3 management: Don't order a renal artery duplex on everyone — pursue it when there are clinical clues (flash pulmonary edema, Cr bump on ACEi, asymmetric kidneys, bruit, young woman with FMD features).

Confirm the diagnosis first:

Baseline labs (every resistant HTN workup):

ECG: LVH (Sokolow-Lyon, Cornell), strain pattern, prior MI, LAE, AFib.

Echocardiogram (recommended in resistant HTN): LVH, diastolic dysfunction, EF, valvular disease — guides therapy and prognosis.

Screening for primary aldosteronism — indicated in ALL resistant HTN patients:

Sleep study: polysomnography (or home sleep test) if any OSA symptoms, obesity, or unexplained resistant HTN — OSA is the single most common secondary cause.

Other targeted tests by clinical suspicion: plasma/urine metanephrines (pheo), 24-h urine free cortisol or overnight 1-mg dexamethasone suppression (Cushing), renal duplex/CTA/MRA (renovascular).

Diagnostic Workup — Advanced or Confirmatory Studies

— Confirmatory test: oral sodium loading with 24-h urine aldosterone, saline infusion test, fludrocortisone suppression, or captopril challenge

— Subtype localization: adrenal CT to identify adenoma vs hyperplasia; in patients ≥35 who are surgical candidates, adrenal venous sampling (AVS) is required to confirm lateralization before adrenalectomy because CT misses microadenomas and shows incidental non-functioning nodules

— Duplex ultrasound is operator-dependent first-line in many centers

— CTA (best anatomic detail; avoid in advanced CKD due to contrast)

— MRA with gadolinium (avoid if eGFR <30 — NSF risk)

— Captopril renography falling out of favor

— Distinguish atherosclerotic (older, ostial, bilateral) from fibromuscular dysplasia ("string of beads," mid/distal artery, young woman)

— Plasma free metanephrines (sensitive) or 24-h urinary fractionated metanephrines (specific) — choose based on pretest probability

— Avoid TCAs, labetalol, acetaminophen, SSRIs before testing

— Confirmed biochemical disease → CT/MRI adrenals, then MIBG or DOTATATE PET if extra-adrenal/metastatic suspected

— Two of: late-night salivary cortisol, 24-h urine free cortisol, 1-mg overnight dexamethasone suppression

— Then ACTH-dependent vs independent workup

Key distinction: Adrenal venous sampling vs CT alone — Step 3 loves the patient with a "CT adenoma" who actually has bilateral hyperplasia; AVS prevents an unnecessary adrenalectomy.

Board pearl: In suspected pheochromocytoma, never start a β-blocker before adequate α-blockade (phenoxybenzamine or doxazosin) — unopposed α stimulation can precipitate hypertensive crisis.

Confirming primary aldosteronism (after positive ARR):

Renovascular HTN evaluation:

Pheochromocytoma:

Cushing syndrome:

Coarctation: TTE, then CT/MR aortography.

OSA confirmation: AHI ≥5 with symptoms or AHI ≥15 regardless.

Risk Stratification and First-Line Management Logic

1. Confirm BP with ABPM/HBPM and rule out white coat

2. Verify adherence — pill counts, pharmacy data, simplify regimen, address cost (generic substitutions, 90-day fills, $4 lists)

3. Identify and remove interfering substances — stop NSAIDs, decongestants, switch from OCP if feasible, treat OSA

4. Lifestyle intensification — dietary sodium <1500 mg/day (especially salt-sensitive), DASH diet, weight loss (~1 mmHg per kg), aerobic exercise 150 min/week, alcohol limits, smoking cessation

5. Optimize the 3-drug regimen before adding a 4th:

— Maximize doses of ACEi/ARB and CCB

— Switch HCTZ to chlorthalidone (12.5–25 mg) or indapamide; switch to loop diuretic if eGFR <30 or volume-overloaded CKD

— Ensure once-daily, long-acting formulations to improve adherence

6. Screen for secondary causes (primary aldosteronism, OSA, renovascular, pheo, Cushing, CKD, coarctation, thyroid)

7. Add 4th-line agent (see chunks 7–8)

— Calculate 10-year ASCVD risk; resistant HTN itself confers excess CV risk regardless of score

— Look for target-organ damage: LVH, albuminuria, CKD, retinopathy, prior stroke/MI — these patients need tighter control and earlier escalation

— BP goal in resistant HTN: generally <130/80 (AHA/ACC); individualize in frail elderly or those with orthostasis

Step 3 management: A patient on max-dose lisinopril, amlodipine, and HCTZ 25 with BP 142/88 — the single best next step is switch HCTZ to chlorthalidone 25 mg, not add a 4th drug. This is among the most-tested moves in resistant HTN.

Board pearl: Treating OSA with CPAP modestly lowers BP (~2–3 mmHg) but is often disproportionately effective in resistant HTN — and remains the right answer when OSA is identified.

Step-wise approach (memorize for CCS-style cases):

Risk stratification:

Pharmacotherapy — First-Line Drug Regimen and 4th-Line Add-On

— ACEi or ARB at max tolerated dose (lisinopril 40, losartan 100, valsartan 320) — never combine the two

— Dihydropyridine CCB (amlodipine 10) — long-acting, smooth 24-h coverage

— Long-acting thiazide-type diuretic: chlorthalidone 12.5–25 mg or indapamide 1.25–2.5 mg (preferred over HCTZ)

— Switch to loop diuretic (furosemide BID or torsemide daily) if eGFR <30 or symptomatic volume overload

— Spironolactone 25–50 mg daily is the evidence-based preferred 4th drug in resistant HTN (PATHWAY-2 trial showed superiority over bisoprolol and doxazosin)

— Works regardless of aldosterone level — most resistant HTN has a volume/sodium-retention phenotype

— Monitor K+ and Cr at 2–4 weeks, then periodically; hold if K >5.5

— Side effects: gynecomastia (~6%), breast tenderness, hyperkalemia → switch to eplerenone 50 mg BID if intolerable (more selective, less gynecomastia)

— β-blocker (especially if HR >70, CAD, HFrEF) — bisoprolol, metoprolol succinate, or labetalol/carvedilol (combined α/β)

— α-blocker (doxazosin) — useful in BPH coexistence; watch orthostasis

— Central agonist: clonidine patch (avoid oral due to rebound HTN), guanfacine

— Direct vasodilators: hydralazine (lupus-like syndrome, reflex tachycardia — pair with β-blocker and diuretic), minoxidil (potent; causes hirsutism, pericardial effusion, marked fluid retention — reserve for refractory)

— Sacubitril/valsartan if concurrent HFrEF

Board pearl: Spironolactone is the best 4th drug for resistant HTN — true even when aldosterone and renin are normal. PATHWAY-2 is high-yield.

Step 3 management: Before starting spironolactone, check baseline K and Cr; avoid if K >5.0 or eGFR <30; recheck within 2–4 weeks of initiation and dose change.

Core 3-drug backbone (must be optimized before declaring resistance):

4th-line agent — the PATHWAY-2 answer:

If MRA contraindicated or insufficient — 5th-line options:

Procedural and Device-Based Therapy

— Catheter-based radiofrequency or ultrasound ablation of renal sympathetic nerves

— FDA-approved (2023) for resistant/uncontrolled HTN as adjunct to medication

— Modest office BP reduction (~5–10 mmHg systolic) in sham-controlled trials (SPYRAL HTN-ON MED, RADIANCE-HTN)

— Best for patients with confirmed adherence, true resistance, and tolerance issues with additional drugs

— Not first-line; reserve after MRA optimization and secondary-cause exclusion

— Atherosclerotic RAS: medical therapy is first-line (CORAL trial showed no mortality/renal benefit from routine stenting) — stent only for: flash pulmonary edema, refractory HTN despite max therapy, progressive renal dysfunction, short duration of HTN

— Fibromuscular dysplasia: percutaneous transluminal angioplasty (PTA) without stenting is preferred; often curative

— Unilateral lateralizing aldosteronoma confirmed by AVS → laparoscopic adrenalectomy can cure or markedly improve HTN

— Bilateral hyperplasia → lifelong spironolactone/eplerenone, not surgery

— Pheochromocytoma: surgical resection after adequate α-blockade (10–14 days), volume expansion, then β-blockade

— Cushing adenoma: transsphenoidal resection (pituitary) or adrenalectomy

Key distinction: In atherosclerotic RAS, stenting does not improve outcomes over medical therapy in most patients (CORAL); in FMD, angioplasty is therapeutic and often eliminates HTN. Step 3 tests this directly.

Board pearl: Operate on a pheochromocytoma only after α-blockade is established and the patient is volume-replete with target HR ~60–80 and mild orthostasis — premature surgery can trigger intraoperative hypertensive crisis.

Renal denervation (RDN):

Baroreflex activation therapy: implantable carotid sinus stimulator — investigational, limited use.

Revascularization for renovascular HTN:

Adrenalectomy:

Coarctation: surgical repair or endovascular stenting.

CPAP for OSA: device, not procedure, but high-yield adjunct.

Special Populations — Elderly and Renal/Hepatic Impairment

— SPRINT showed benefit of SBP <130 even in fit older adults, but avoid in frail, institutionalized, or orthostatic-prone patients

— Reasonable target: SBP 130–140 in those with multimorbidity, fall risk, or limited life expectancy

— Always check orthostatic vitals before titration

— Start low, titrate slow; prefer once-daily long-acting agents to ease adherence

— Avoid clonidine (sedation, fall risk, rebound HTN if missed), α-blockers as monotherapy (orthostasis), high-dose β-blockers (bradycardia, fatigue)

— Monitor electrolytes and renal function closely with thiazide + MRA combinations — hyperkalemia and hyponatremia risk are higher

— BP goal <130/80 (KDIGO 2021 recommends <120 systolic by standardized measurement in many patients with CKD)

— ACEi or ARB is foundational if albuminuria present — accept a Cr rise up to 30% and K up to 5.5 before stopping

— Switch thiazide → loop diuretic when eGFR <30 (thiazides lose efficacy; chlorthalidone can still help mildly to eGFR ~20)

— MRA caution: spironolactone/eplerenone increase hyperkalemia risk; finerenone (nonsteroidal MRA) approved for diabetic CKD — lowers CV and renal events with less hyperkalemia

— Consider patiromer or sodium zirconium to enable RAAS/MRA continuation when K trending high

— SGLT2 inhibitors add modest BP lowering and renal/CV benefit in diabetic and non-diabetic CKD

Step 3 management: In a CKD stage 4 patient on lisinopril + amlodipine + chlorthalidone with BP 145/85, the right move is switch chlorthalidone to furosemide BID or torsemide daily (thiazides ineffective at low eGFR) before adding a 4th drug.

Board pearl: A Cr bump >30% or development of hyperkalemia after starting ACEi in an older patient with resistant HTN should trigger evaluation for bilateral renal artery stenosis.

Elderly (≥65, especially ≥80):

CKD (eGFR <60):

Hepatic impairment: avoid methyldopa (hepatotoxicity), labetalol (rare hepatitis); dose-adjust carvedilol.

Special Populations — Pregnancy and Other Demographic Subgroups

— Safe agents: labetalol, nifedipine ER, methyldopa, hydralazine (acute)

— Contraindicated: ACEi, ARB, direct renin inhibitors, MRAs (spironolactone — anti-androgenic to male fetus), atenolol (IUGR), nitroprusside (cyanide), thiazides (relative — volume contraction)

— BP goal in pregnancy (CHAP trial 2022): <140/90 improves outcomes without increasing small-for-gestational-age babies

— Resistant HTN in pregnancy → urgent eval for preeclampsia, secondary causes (pheo in pregnancy is rare but lethal — order plasma metanephrines if classic spells)

— Postpartum: BP often peaks 3–6 days postpartum; close follow-up at 1 week, continue safe agents while breastfeeding (labetalol, nifedipine, enalapril, captopril compatible)

— Higher prevalence of resistant HTN, salt-sensitive, low-renin phenotype

— Initial therapy favors thiazide + CCB; ACEi/ARB monotherapy less effective but indicated with CKD, DM, HF

— Excellent response to chlorthalidone and spironolactone

— Higher angioedema risk with ACEi → ARB preferred if angioedema history

— Resistant HTN at young age → high suspicion for secondary cause: renovascular (FMD), coarctation, monogenic syndromes (Liddle, Gordon, glucocorticoid-remediable aldosteronism, apparent mineralocorticoid excess)

— Liddle → amiloride/triamterene (not spironolactone); AME → spironolactone; GRA → low-dose glucocorticoid

Key distinction: In pregnancy, spironolactone is contraindicated; the resistant HTN 4th-line workhorse off-label outside pregnancy becomes unavailable — use labetalol, extended-release nifedipine, or hydralazine combinations instead.

Board pearl: A teenager with severe HTN, hypokalemia, low aldosterone, and low renin = Liddle syndrome → treat with amiloride or triamterene, not spironolactone.

Pregnancy:

Black/African-American patients:

Adolescents/young adults:

Transgender patients on gender-affirming hormones: estrogens can raise BP; monitor closely.

Complications and Adverse Outcomes

— LVH and diastolic dysfunction → HFpEF

— Coronary artery disease, MI

— HFrEF from chronic afterload

— Atrial fibrillation (LAE secondary to HTN)

— Aortic dissection — classically in poorly controlled chronic HTN; tearing chest/back pain

— Ischemic and hemorrhagic stroke (resistant HTN doubles stroke risk vs controlled HTN)

— Hypertensive encephalopathy, PRES

— Vascular cognitive impairment and dementia

— Accelerated CKD progression, nephrosclerosis

— Albuminuria as early marker

— ESRD requiring dialysis

— MRA: hyperkalemia, AKI, gynecomastia

— Thiazide: hypokalemia, hyponatremia, hyperuricemia/gout, hyperglycemia, hypercalcemia

— Loop: hypokalemia, ototoxicity, volume depletion

— ACEi: cough, angioedema, hyperkalemia, AKI

— CCB (dihydropyridine): peripheral edema, reflex tachycardia

— Non-DHP CCB: bradycardia, AV block, constipation

— Hydralazine: lupus-like syndrome, reflex tachycardia

— Minoxidil: pericardial effusion, hirsutism, edema

— Clonidine: rebound HTN on abrupt discontinuation

Step 3 management: For a patient in hypertensive urgency found at clinic with BP 200/115 but asymptomatic, do not give IV labetalol or sublingual nifedipine — restart/intensify oral regimen and arrange close follow-up within 24–72 hours.

Board pearl: Sublingual nifedipine is contraindicated for hypertensive urgency — precipitous drops cause stroke and MI.

Cardiovascular:

Cerebrovascular:

Renal:

Retinal: hypertensive retinopathy (grades 1–4), retinal vein occlusion, choroidopathy.

Hypertensive emergency: BP >180/120 with target-organ damage (encephalopathy, MI, acute HF/pulmonary edema, dissection, AKI, eclampsia, retinal hemorrhage) — IV agents, controlled lowering (≤25% in first hour, except dissection and ICH which need faster, tighter targets).

Hypertensive urgency: BP >180/120 without acute target-organ damage — oral therapy, gradual lowering over 24–48 h; avoid rapid IV reduction (risk of watershed stroke, MI).

Drug-related complications:

When to Escalate Care — Consult, Inpatient Triage, ICU

— Aortic dissection → IV esmolol or labetalol first (HR <60), then nitroprusside or nicardipine; goal SBP <120 in 20 min

— Acute pulmonary edema/HFpEF crisis → IV nitroglycerin + loop diuretic, avoid β-blockers acutely

— Acute coronary syndrome → nitroglycerin, β-blocker, ACEi

— Acute ischemic stroke → permissive HTN; treat only if >220/120 (or >185/110 if tPA candidate)

— Intracerebral hemorrhage → SBP target 130–140 acutely (INTERACT-2)

— Hypertensive encephalopathy → nicardipine or labetalol; reduce MAP ~25% in first hour

— Eclampsia/severe preeclampsia → IV labetalol or hydralazine + magnesium sulfate

— Pheochromocytoma crisis → phentolamine or nicardipine; never β-blocker first

— Acute kidney injury with malignant HTN → ICU; consider fenoldopam

— Hypertension specialist/nephrology if BP remains uncontrolled despite optimized 4-drug regimen including MRA

— Endocrinology for confirmed primary aldosteronism (esp. for AVS), pheo, Cushing

— Sleep medicine for OSA evaluation

— Cardiology for LVH/HFpEF, suspected coarctation, CAD

— Vascular surgery/interventional radiology for renovascular disease needing revascularization

— OB-MFM for resistant HTN in pregnancy

CCS pearl: In a CCS case of suspected aortic dissection with HTN, the order set is: type and crossmatch, CTA chest/abdomen/pelvis, IV esmolol (HR <60 FIRST), THEN nitroprusside or nicardipine, surgical consult, ICU bed. Don't drop SBP before controlling HR — unopposed vasodilation increases shear stress and propagates dissection.

Board pearl: Permissive HTN in acute ischemic stroke — do not lower BP unless >220/120 or planning tPA/thrombectomy (target <185/110).

Hospitalize/ICU for hypertensive EMERGENCY (BP elevation with acute end-organ damage):

Specialty referrals (outpatient):

Key Differentials — Same-Category (Hypertension) Causes

— White-coat effect: elevated office BP, normal ABPM/HBPM — ~30% of apparent resistant

— Masked hypertension: normal office, elevated home — opposite phenomenon, also requires ABPM

— Non-adherence: ~30–50% of "resistant" patients; verify with pharmacy fills, urine/serum drug levels at specialty centers, witnessed dosing

— Suboptimal regimen: missing diuretic, wrong diuretic (HCTZ instead of chlorthalidone), submax doses, short-acting agents

— Measurement error: small cuff, no rest, talking, arm position

— NSAIDs — common in OA, raises BP ~5 mmHg and blunts diuretics/ACEi

— Decongestants (pseudoephedrine, phenylephrine)

— OCPs / hormone replacement — estrogen effect

— Stimulants — cocaine, methamphetamine, amphetamines, ADHD meds, energy drinks, MDMA

— Alcohol >2 drinks/day men, >1 women

— Licorice (glycyrrhizin → AME-like syndrome with hypokalemia)

— Steroids — chronic prednisone, anabolic steroids

— Calcineurin inhibitors (cyclosporine, tacrolimus)

— EPO/ESAs

— VEGF inhibitors (bevacizumab, sunitinib) — classic in cancer patients

— Herbals: ephedra, ma-huang, yohimbe, bitter orange, ginseng

— MAO inhibitors with tyramine

— SNRIs (venlafaxine), high-dose TCAs

Key distinction: Resistant HTN is a diagnosis of exclusion — before invoking it, confirm out-of-office BP, document adherence, check for offending substances, and ensure the regimen includes an optimized long-acting thiazide-type diuretic.

Board pearl: A patient with controlled HTN whose BP rises after starting chronic ibuprofen for OA — the right answer is stop the NSAID (or switch to topical/acetaminophen), not add a 4th antihypertensive.

Pseudoresistant hypertension (the most common "mimic"):

Drug- and substance-induced HTN (always reversible cause to identify):

Salt-sensitive essential HTN: dietary sodium >3 g/day worsens control, especially in Black, elderly, CKD, and DM patients.

Key Differentials — Other-Category (Secondary) Causes

— Atherosclerotic RAS — older smokers; medical therapy first (CORAL)

— FMD — young women, "string of beads"; angioplasty

Key distinction: OSA vs primary aldosteronism — both are common, often coexist, and both should be screened in essentially every resistant HTN workup. They are not "either/or."

Board pearl: Hypokalemia in a hypertensive patient = think aldosterone excess (primary aldosteronism, RAS, licorice, AME, Cushing) before assuming diuretic-induced — order ARR before correcting K with spironolactone.

Step 3 management: A patient with resistant HTN, paroxysmal headaches + sweating + palpitations during physical exam → order plasma free metanephrines; do not start a β-blocker first.

Obstructive sleep apnea — most common secondary cause; treat with CPAP, weight loss, positional therapy.

Primary aldosteronism — most common endocrine cause (~20% of resistant HTN); hypokalemia not required; ARR screen → confirm → CT + AVS → adrenalectomy vs MRA.

Renovascular disease:

CKD of any cause — volume overload and RAAS activation drive HTN; needs loop diuretic and MRA carefully.

Pheochromocytoma/paraganglioma — episodic spells; plasma/urinary metanephrines; α-block → β-block → resect.

Cushing syndrome — exogenous steroids most common; endogenous via pituitary/adrenal/ectopic ACTH.

Thyroid disease — hyperthyroidism (systolic, wide pulse pressure), hypothyroidism (diastolic HTN).

Hyperparathyroidism — hypercalcemia-mediated.

Aortic coarctation — young, differential BPs, radio-femoral delay.

Monogenic syndromes: Liddle (ENaC gain-of-function, low renin/low aldo, hypokalemia, treat with amiloride), Gordon (PHA2, hyperkalemia, treat with thiazide), glucocorticoid-remediable aldosteronism (treat with low-dose dex), apparent mineralocorticoid excess (cortisol acts at MR; treat with spironolactone).

Acromegaly — coarse features, large hands/feet, IGF-1 elevation.

Polycythemia, polycystic kidney disease.

Secondary Prevention, Discharge Medications, and Long-Term Plan

— Statin based on ASCVD risk calculator: high-intensity (atorvastatin 40–80, rosuvastatin 20–40) if clinical ASCVD, LDL ≥190, DM 40–75 with high risk, or 10-yr ASCVD ≥20%

— Aspirin 81 mg: secondary prevention only; primary prevention selective (ages 40–59 with high risk and low bleed risk per USPSTF) — not routine in resistant HTN

— Diabetes management: A1c individualized (~7%), prefer SGLT2 inhibitor (BP lowering, CV/renal benefit) and GLP-1 RA in high-risk diabetics

— Smoking cessation — pharmacotherapy (varenicline, bupropion, NRT) + counseling

— Weight loss — 5–10% body weight loss → meaningful BP reduction; consider GLP-1 RA, bariatric surgery in select patients (BMI ≥35 with comorbidity, ≥40 without)

— Reconcile all home medications; resume long-acting agents, avoid short-acting

— Provide 30-day supply and confirm pharmacy availability

— Document BP targets in discharge summary

— Address transition-of-care risk: clonidine never as a discharge med unless patient already on it (rebound risk if missed)

— DASH diet + sodium <1500 mg/day

— 150 min/week moderate aerobic + resistance training 2–3×/week

— Alcohol ≤2 drinks/day men, ≤1 women; many recommend less

— Treat OSA with CPAP, optimize sleep duration ≥7 h

— Vaccinations: annual influenza, pneumococcal, COVID-19, RSV if ≥60

— Address mental health: depression and anxiety worsen adherence

Step 3 management: When discharging a patient after a hypertensive urgency admission, never rely on clonidine as the new "controller" — its abrupt discontinuation (common in nonadherent patients) precipitates rebound HTN crisis. Prefer amlodipine, chlorthalidone, and lisinopril combinations.

Board pearl: SGLT2 inhibitors lower SBP by ~4–5 mmHg in addition to glycemic, CV, and renal benefits — strongly consider in resistant HTN with DM or CKD.

Comprehensive CV risk reduction (must address with resistant HTN):

Discharge med checklist after hypertensive admission:

Long-term plan:

Follow-Up, Monitoring Parameters, and Counseling

— After regimen change: clinic or telehealth visit in 2–4 weeks with home BP log

— Once at goal: every 3–6 months, annual labs at minimum

— After starting/uptitrating ACEi/ARB or MRA: BMP at 2–4 weeks, then at 3 months and with any dose change or intercurrent illness

— After diuretic change: BMP at 1–2 weeks (K, Na, Cr, uric acid)

— Annual UACR, lipid panel, A1c (if DM), TSH as indicated

— Validated upper-arm oscillometric device (wrist devices unreliable)

— Measure twice in the morning and twice in the evening for 7 days; discard day 1; average remainder

— Avoid caffeine/exercise/smoking 30 min prior; empty bladder; sit quietly 5 min; feet flat; no talking

— Bring the device to clinic annually for validation against office reading

— Patient-recorded BP logs improve adherence and decision-making

— Sodium <1500 mg/day (read labels; restaurant meals are the big offenders)

— DASH: fruits, vegetables, whole grains, low-fat dairy, nuts, lean protein

— Weight loss target: 5–10% of body weight

— Exercise prescription: 30 min × 5 days/week moderate aerobic + 2 sessions resistance

— Alcohol limits and screening with AUDIT-C

— Sleep ≥7 h, screen for OSA with STOP-BANG

— Single-pill fixed-dose combinations improve adherence dramatically

— 90-day fills, mail order, synchronization of refill dates

— Reminder apps, pill organizers

— Address cost — switch to generics, $4 lists, GoodRx, patient assistance

Step 3 management: A patient with resistant HTN on 4 separate pills can often be consolidated to 2 fixed-dose combinations (e.g., olmesartan/amlodipine/HCTZ + spironolactone) — improving adherence may obviate further drug additions.

Board pearl: Use a validated home BP cuff and a 7-day average — single home readings (especially first-of-the-day or stress readings) overestimate "uncontrolled" status and lead to overtreatment.

Follow-up cadence:

Home BP monitoring (HBPM) counseling:

Lifestyle counseling — concrete targets:

Adherence interventions:

Ethical, Legal, and Patient Safety Considerations

— Non-judgmental exploration of barriers (cost, side effects, health literacy, depression, mistrust of medical system) before escalation

— Avoid labeling patients "non-compliant" in the chart — replace with "adherence challenges"

— Shared decision-making about pill burden, side effects (e.g., MRA-induced gynecomastia, sexual dysfunction)

— Cultural humility, especially in Black communities where medical mistrust is historically grounded; affordable, accessible care is part of ethical practice

— Before renal denervation, adrenalectomy, or stenting: discuss the modest average effect, irreversibility (denervation), surgical risks, and that medical therapy is often equivalent

— Before adrenal venous sampling: explain procedural risks (adrenal hemorrhage, contrast)

— Pheochromocytoma surgery: explain the need for weeks of preoperative α-blockade before any anesthetic exposure

— Hypertensive urgency discharged without timely outpatient follow-up (within 3–7 days) is a defined patient-safety failure

— Medication reconciliation at every transition; deprescribe duplicates (e.g., ARB + ACEi inadvertently continued)

— Clonidine rebound HTN if abruptly stopped — a known harm in poorly coordinated discharges; flag clonidine on med lists explicitly

— Communicate BP targets and labs due to PCP via discharge summary within 48 h

— Symptomatic orthostasis from titration → counsel about fall risk, syncope, driving

— Pilots, commercial drivers (DOT) — BP thresholds may affect licensure; document control carefully

— Pheochromocytoma genetic syndromes (MEN2, VHL, NF1, SDHx) → counsel about family genetic testing — ethical obligation to inform at-risk relatives, ideally via the patient ("duty to warn" duties vary by state)

— Sham-controlled trials (renal denervation) require careful consent given the placebo procedure

Board pearl: A patient discharged after hypertensive urgency on clonidine without follow-up who returns 5 days later with rebound HTN crisis and stroke is a classic transition-of-care safety failure — the systems answer is early follow-up + medication reconciliation + avoiding clonidine as a new agent.

Adherence ethics — the non-adherent patient:

Informed consent edge cases:

Transition-of-care safety (high-yield Step 3):

Driving and occupational safety:

Mandatory reporting and legal:

Research/clinical trial ethics:

High-Yield Associations and Rapid-Fire Clinical Facts

Board pearl: Memorize this triad to crack any resistant HTN stem: (1) confirm with ABPM, (2) switch HCTZ to chlorthalidone, (3) add spironolactone. This is the answer ~70% of the time.

Resistant HTN definition: uncontrolled on 3 drugs including diuretic OR controlled on ≥4 drugs.

Most common 4th drug (PATHWAY-2): spironolactone.

Most common secondary cause: OSA.

Most common endocrine secondary cause: primary aldosteronism (~20%).

Switch HCTZ → chlorthalidone: classic exam move; ~2× more potent and longer-acting.

Loop diuretic when eGFR <30: thiazides lose efficacy.

Spironolactone contraindications: K >5.0, eGFR <30, pregnancy.

Eplerenone: less gynecomastia, fewer endocrine side effects than spironolactone.

Finerenone: nonsteroidal MRA — diabetic CKD; less hyperkalemia.

CORAL trial: renal stenting no better than meds for atherosclerotic RAS.

FMD: young woman, "string of beads," angioplasty curative.

Pheochromocytoma rule: α before β, always.

Liddle syndrome: low renin, low aldo, hypokalemia → amiloride (not spironolactone).

GRA: dexamethasone-responsive aldosteronism → low-dose dexamethasone.

AME: cortisol acts at MR (11β-HSD2 deficiency) → spironolactone.

NSAIDs raise BP 3–5 mmHg and blunt diuretics, ACEi/ARB, β-blockers.

Sublingual nifedipine: contraindicated for urgency — strokes and MIs.

Hypertensive emergency target: reduce MAP ≤25% in 1st hour (faster only for dissection: SBP <120 in 20 min; ICH SBP 130–140).

Acute ischemic stroke BP: treat only if >220/120 (or >185/110 for tPA).

CHAP trial: treat chronic HTN in pregnancy to <140/90; safe agents are labetalol, nifedipine ER, methyldopa.

ARR screen: positive if aldo >10 + ratio >20.

AVS required before adrenalectomy in patients ≥35 to confirm lateralization.

CPAP for OSA: modest direct BP effect but disproportionately useful in resistant HTN.

SGLT2 inhibitors: ~4–5 mmHg SBP reduction, CV/renal benefit.

Salt restriction <1500 mg/day: most effective in Black, elderly, CKD, DM patients.

Renal denervation: FDA-approved 2023; adjunct, not replacement.

Clonidine rebound HTN: never abrupt stop; avoid as new discharge med.

Board Question Stem Patterns

— Stem: patient with elevated office BPs on 3 drugs; ABPM shows normal daytime average.

— Answer: white-coat HTN; no medication change; continue current regimen, repeat home BP.

— Stem: patient on lisinopril 40, amlodipine 10, HCTZ 25; BP 144/90 confirmed at home.

— Answer: switch HCTZ to chlorthalidone 25 mg (do not add a 4th drug yet).

— Stem: BP uncontrolled on chlorthalidone + ACEi + amlodipine, K 4.0, eGFR 65.

— Answer: add spironolactone 25 mg daily; recheck K/Cr in 2–4 weeks.

— Stem: obese man with snoring, daytime sleepiness, resistant HTN.

— Answer: order polysomnography; initiate CPAP if AHI ≥5 with symptoms.

— Stem: hypokalemia on a thiazide that is "out of proportion"; resistant HTN.

— Answer: plasma aldosterone-to-renin ratio; confirm; CT; AVS; adrenalectomy vs MRA.

— Stem: older smoker with flash pulmonary edema and Cr bump after starting lisinopril.

— Answer: bilateral atherosclerotic renal artery stenosis; stop ACEi, image with duplex/CTA; medical therapy unless refractory.

— Stem: young woman with new severe HTN, abdominal bruit, no atherosclerosis.

— Answer: fibromuscular dysplasia; angioplasty, not stent.

— Stem: episodic headache/palpitations/sweating with resistant HTN.

— Answer: plasma free metanephrines; α-blockade before β-blockade.

— Stem: previously controlled HTN now uncontrolled after starting chronic ibuprofen.

— Answer: stop NSAID (offer acetaminophen/topical alternatives).

— Stem: pregnant woman with chronic HTN uncontrolled on methyldopa.

— Answer: add or switch to labetalol or nifedipine ER; never ACEi/ARB/spironolactone.

— Stem: asymptomatic BP 210/120 in clinic.

— Answer: oral therapy, gradual lowering over 24–48 h, close follow-up; not IV agents, not sublingual nifedipine.

Board pearl: The stem-discriminator is whether out-of-office BP is confirmed and whether the diuretic is chlorthalidone/indapamide — both must be true before you "add a 4th drug."

Pattern 1 — The pseudoresistance trap:

Pattern 2 — The diuretic swap:

Pattern 3 — The PATHWAY-2 stem:

Pattern 4 — The OSA stem:

Pattern 5 — The aldosteronism stem:

Pattern 6 — The renovascular stem:

Pattern 7 — The FMD stem:

Pattern 8 — The pheo stem:

Pattern 9 — The NSAID stem:

Pattern 10 — The pregnancy stem:

Pattern 11 — The hypertensive urgency stem:

One-Line Recap

Resistant hypertension is BP above goal on 3 maximally dosed agents including a long-acting thiazide-type diuretic (or controlled on ≥4), and its evaluation requires confirming out-of-office BP, ensuring adherence, removing interfering substances, screening universally for OSA and primary aldosteronism, optimizing the regimen (especially switching HCTZ to chlorthalidone), and adding spironolactone as the evidence-based 4th-line agent.

Board pearl: When in doubt on a resistant HTN stem — confirm with ABPM, swap HCTZ for chlorthalidone, screen for OSA and primary aldosteronism, and add spironolactone. That single algorithm answers the majority of Step 3 questions on this topic.

Confirm before you escalate: ABPM/HBPM + adherence check + med/supplement review + correct BP technique → eliminates pseudoresistance in 30–50% of "resistant" patients.

Optimize before you add: max-dose ACEi/ARB + dihydropyridine CCB + chlorthalidone or indapamide (or loop if eGFR <30); single-pill combos boost adherence.

Screen secondary causes universally: OSA (polysomnography), primary aldosteronism (ARR — regardless of K), and selectively pursue renovascular (flash pulmonary edema, Cr bump on ACEi), pheo (spells), Cushing, coarctation, thyroid, CKD, monogenic syndromes in young patients.

4th-line is spironolactone (PATHWAY-2) — monitor K/Cr at 2–4 weeks; eplerenone if gynecomastia; finerenone for diabetic CKD; then add β-blocker, α-blocker, central agent, or vasodilator as needed; renal denervation is an adjunct, not a replacement.

Special populations: pregnancy → labetalol/nifedipine ER/methyldopa (no ACEi/ARB/MRA); CKD → loop + cautious MRA + possibly finerenone; elderly → individualized targets and orthostatic checks; Black patients → thiazide + CCB + MRA work best.

Transition-of-care safety: avoid initiating clonidine at discharge (rebound risk), ensure follow-up within 1–2 weeks of any regimen change, and never use sublingual nifedipine for urgency.