Why do diuretics not demonstrate a mortality benefit in patients with heart failure with preserved ejection fraction (HFpEF) despite improving symptoms?

Why Diuretics Have Not Shown Mortality Benefit Despite Clear Symptomatic Benefits

Diuretics have never been tested in long-term randomized controlled trials designed to assess mortality in heart failure, and their mechanism of action—relieving congestion without modifying the underlying neurohormonal activation and disease progression—explains why they improve symptoms rapidly but do not reduce death rates. 1

The Evidence Gap: No Long-Term Mortality Trials

The fundamental reason we lack mortality data for diuretics is straightforward:

• There have been no long-term studies of diuretic therapy in heart failure, and thus their effects on morbidity and mortality are not known 1
• All controlled trials with diuretics have been short-term or intermediate-term studies focused on symptom relief, demonstrating ability to increase urinary sodium excretion, decrease physical signs of fluid retention, improve cardiac function, symptoms, and exercise tolerance—but none were powered or designed to assess mortality 2, 1
• The 2022 ACC/AHA guidelines explicitly state: "With the exception of mineralocorticoid receptor antagonists, the effects of diuretics on morbidity and mortality are uncertain" 2

Why Diuretics Don't Modify Disease Progression

The mechanistic explanation centers on what diuretics do versus what they don't do:

What Diuretics Accomplish

• Diuretics produce symptomatic benefits more rapidly than any other drug for heart failure, relieving pulmonary and peripheral edema within hours or days 1
• They are the only drugs that can adequately control fluid retention in heart failure 1
• They relieve congestion, improve symptoms, and prevent worsening heart failure 2

What Diuretics Fail to Address

• Diuretics alone are unable to maintain clinical stability of patients with heart failure for long periods of time 1
• Even when successful in controlling symptoms and fluid retention, diuretics do not modify the underlying neurohormonal activation driving disease progression 1
• The higher the dose of loop diuretics needed to maintain patient stability, the worse the prognosis, which most likely reflects disease burden and sodium avidity rather than any harmful effect of the diuretic itself 3

The Paradox: Symptom Relief Without Survival Benefit

Recent trial data illuminate this disconnect:

• DOSE-AHF trial: High-dose diuretics produced greater symptom relief, higher urine output, and more substantial weight loss, but this did not affect death, rehospitalization, or emergency department visits during 60-day follow-up 3
• TRANSFORM-HF trial: Comparing torsemide versus furosemide showed no difference in 12-month mortality between the two loop diuretics despite theoretical pharmacokinetic advantages 3
• ADVOR and CLOROTIC trials: Adding acetazolamide or hydrochlorothiazide to loop diuretics resulted in more efficient decongestion but without any positive effect on post-discharge outcomes (mortality or rehospitalizations), and death rates were numerically higher in active treatment arms 3

The Critical Clinical Implication

Diuretics should not be used in isolation but always combined with guideline-directed medical therapy that reduces hospitalizations and prolongs survival 2:

• The risk of clinical decompensation can be reduced when diuretics are combined with ACE inhibitors/ARBs/ARNIs, beta-blockers, and mineralocorticoid receptor antagonists 1
• In HFpEF specifically, no treatment including diuretics has convincingly shown mortality benefit, though SGLT2 inhibitors now demonstrate reduced cardiovascular death or heart failure hospitalizations 4, 5
• Diuretics remain essential for symptom management and enabling optimal use of disease-modifying therapies, but they are symptomatic therapy, not disease-modifying therapy 2, 3

Common Pitfalls to Avoid

• Inappropriately low doses of diuretics result in fluid retention, which diminishes response to ACE inhibitors and increases risk with beta-blocker treatment 1
• Inappropriately high doses lead to volume contraction, increasing risk of hypotension with ACE inhibitors/vasodilators and renal insufficiency with ACE inhibitors/ARBs 1
• Using diuretics alone without disease-modifying therapies leaves patients vulnerable to clinical decompensation despite symptom control 1

The treatment goal is to eliminate clinical evidence of fluid retention using the lowest dose possible to maintain euvolemia, always as part of a comprehensive strategy that includes agents proven to reduce mortality 2, 4.