A 48-year-old woman with a 10-year history of hypertension presents with persistent BP of 152/94 mmHg despite compliance with enalapril 20 mg daily and amlodipine 10 mg daily. She denies headaches, chest pain, or dyspnea. Serum sodium is 138 mEq/L, potassium 4.8 mEq/L, and creatinine 0.9 mg/dL. Urinalysis is normal. What is the most appropriate next step?

Explanation

## Clinical Scenario Analysis This patient has **resistant hypertension** — BP remains uncontrolled despite use of two antihypertensive drug classes at maximum doses (ACE inhibitor + calcium channel blocker). The most appropriate next step is to add a **mineralocorticoid receptor antagonist (spironolactone 25 mg daily)** as the third agent. ## Definition of Resistant Hypertension **Key Point:** Resistant hypertension is defined as BP that remains above goal despite concurrent use of ≥3 antihypertensive agents of different classes at optimal doses, ideally including a diuretic. This patient is on only **two** agents — she does not yet meet the full definition of resistant hypertension requiring secondary workup before adding a third drug. **High-Yield:** Current guidelines (JNC 8, ESC/ESH 2018, AHA/ACC 2017) recommend a **three-drug combination** of an ACE inhibitor/ARB + CCB + diuretic (preferably thiazide-type) as the standard triple therapy before labeling hypertension as "resistant." Spironolactone, a mineralocorticoid receptor antagonist, is the preferred add-on agent when a thiazide diuretic has not yet been used, and is particularly effective in resistant hypertension. ## Why Spironolactone Is the Best Next Step **Clinical Pearl:** The PATHWAY-2 trial (Williams et al., *Lancet* 2015) demonstrated that spironolactone was significantly superior to other add-on agents (doxazosin, bisoprolol, placebo) in patients with resistant hypertension. It is now considered the **drug of choice as a fourth-line agent** and is appropriate here as the third agent (diuretic component of triple therapy). - This patient's **potassium is 4.8 mEq/L** — borderline but acceptable for initiating spironolactone at 25 mg; close monitoring is warranted - **Creatinine 0.9 mg/dL** — normal renal function, no contraindication - Adding spironolactone addresses the aldosterone-mediated component of hypertension, which is common even without overt primary aldosteronism ## Secondary Hypertension Workup — When Is It Indicated? **Key Point:** Secondary hypertension workup is indicated when BP remains uncontrolled on **three or more** agents at optimal doses (true resistant hypertension), or when clinical clues suggest a secondary cause (e.g., hypokalemia, episodic symptoms, renal bruit, young age). This patient has **none** of these red flags — normal potassium, normal creatinine, normal urinalysis, and no suggestive symptoms. Referring for secondary workup before even attempting triple therapy is premature. ## Why Not Other Options? **Option A (Refer for secondary workup first):** Premature — secondary hypertension workup is indicated after failure of ≥3 agents or when specific clinical clues are present. This patient is only on two agents; the appropriate next step is to optimize to triple therapy first. [Harrison's Principles of Internal Medicine, 21e, Ch. 297] **Option C (Increase amlodipine to 15 mg):** Amlodipine 10 mg daily is the **maximum recommended dose**. Exceeding this is not standard practice and is not supported by evidence; it would increase adverse effects (peripheral edema) without meaningful additional BP reduction. **Option D (Switch enalapril to losartan):** ACE inhibitors and ARBs act on the same RAAS pathway; switching between them does not provide additive antihypertensive benefit and is not recommended. Combination ACEi + ARB is contraindicated due to increased risk of hyperkalemia and renal impairment (ONTARGET trial). **[cite: Harrison 21e Ch 297; PATHWAY-2 Trial, Lancet 2015; AHA/ACC Hypertension Guidelines 2017]**