A 52-year-old man with hypertension is started on atenolol 50 mg daily. After 2 weeks, his blood pressure remains 160/100 mmHg. On examination, heart rate is 58 bpm and regular. He reports no adverse effects. What is the most appropriate next step in management?

## Clinical Context This patient demonstrates inadequate response to monotherapy with a beta-blocker despite adequate dosing and good tolerability. His heart rate of 58 bpm indicates the drug is achieving its pharmacodynamic effect (beta-1 receptor blockade), yet blood pressure control remains suboptimal. ## Pharmacodynamic Principle **Key Point:** Beta-blockers work primarily through β₁-adrenergic receptor antagonism in the heart and kidney, reducing cardiac output and renin release. However, they do not address other mechanisms of hypertension (e.g., peripheral vascular resistance, sodium retention). A single receptor antagonist cannot normalize all pathophysiologic pathways in multifactorial disease. **High-Yield:** In hypertension management, when monotherapy achieves adequate receptor blockade (evidenced by heart rate reduction here) but fails to control blood pressure, the next step is combination therapy targeting complementary mechanisms—not dose escalation of the same agent. ## Rationale for Correct Answer Adding a second agent with a different mechanism (e.g., amlodipine for vasodilation via L-type calcium channel blockade, or lisinopril for ACE inhibition and vasodilation) provides synergistic blood pressure reduction. This follows guideline-recommended step-care for resistant hypertension and is more effective than further beta-blocker dose escalation. ## Clinical Pearl Dose escalation of atenolol beyond 100 mg provides diminishing returns in blood pressure reduction while increasing bradycardia risk. The patient's heart rate of 58 bpm already suggests near-maximal β₁ blockade. ## Why Combination Therapy Works ```mermaid flowchart TD A[Hypertension: Multiple Pathways]:::outcome --> B[Sympathetic overactivity]:::outcome A --> C[Increased peripheral resistance]:::outcome A --> D[Volume expansion/sodium retention]:::outcome B --> E[Beta-blocker: ↓ CO, ↓ renin]:::action C --> F[Calcium channel blocker: ↓ SVR]:::action D --> G[ACE inhibitor: ↓ Angiotensin II]:::action E --> H[Synergistic BP control]:::outcome F --> H G --> H ```