A 58-year-old man with a 3-year history of dilated cardiomyopathy (ejection fraction 28%) and NYHA Class III heart failure is on lisinopril 10 mg daily and metoprolol 50 mg twice daily. His current BP is 110/70 mmHg, HR 68/min, and serum creatinine 1.1 mg/dL. Echocardiography shows no improvement over the past 6 months. What is the most appropriate next step in management?

Explanation

## Clinical Context This patient has systolic heart failure (EF 28%) on guideline-directed medical therapy (GDMT) with an ACE inhibitor and beta-blocker at adequate doses. His haemodynamics are stable, and renal function is preserved. ## Why Aldosterone Antagonist Is Next **Key Point:** The sequential GDMT algorithm for systolic HF is: (1) ACE-I/ARB + beta-blocker, (2) add aldosterone antagonist, (3) add ARNI or hydralazine-nitrate, (4) consider SGLT2i or ivabradine based on EF and HR. **High-Yield:** Aldosterone antagonists (spironolactone, eplerenone) reduce mortality in systolic HF by ~30% [cite:Harrison 21e Ch 297]. They are indicated when EF ≤35% and the patient is on ACE-I and beta-blocker. This patient meets all criteria. **Clinical Pearl:** Before initiating spironolactone, confirm: - Serum K^+^ is normal (3.5–5.0 mEq/L) - eGFR >30 mL/min/1.73m² (patient's Cr 1.1 is acceptable) - No contraindications (renal artery stenosis, severe renal disease) ## Mechanism of Benefit Aldosterone antagonists block mineralocorticoid receptors in the collecting duct, reducing sodium reabsorption and potassium loss. They also reduce cardiac fibrosis and neurohormonal activation independent of blood pressure. ## Dosing Sequence | Drug | Starting Dose | Target Dose | Monitoring | | --- | --- | --- | --- | | Spironolactone | 12.5 mg daily | 25–50 mg daily | K^+^, Cr at 1 week, 4 weeks, then 3-monthly | | Eplerenone | 25 mg daily | 50 mg daily | K^+^, Cr at 1 week, 4 weeks, then 3-monthly | **Tip:** Eplerenone is more selective (fewer gynaecomastia/sexual dysfunction) but more expensive; spironolactone is first-line in resource-limited settings. ## Why Other Options Are Premature **Metoprolol:** Already at 50 mg twice daily (standard maintenance). Increasing further without evidence of inadequate rate control or persistent symptoms is not indicated at this stage. **Lisinopril:** Already at 10 mg daily (standard target). Increasing ACE-I dose without evidence of underdosing (or adding a second RAAS inhibitor) violates the sequential algorithm. **Dobutamine:** Reserved for acute decompensation with hypotension/cardiogenic shock. This patient is euvolaemic and haemodynamically stable; inotropes worsen long-term outcomes in chronic HF.