Which landmark randomized trials have shaped current guideline‑directed therapy for heart failure with reduced ejection fraction and heart failure with preserved ejection fraction?

Landmark Trials Shaping Heart Failure Management

Heart Failure with Reduced Ejection Fraction (HFrEF)

The evidence base for HFrEF is built on multiple landmark trials that established quadruple guideline-directed medical therapy, which provides a 73% mortality reduction over 2 years when fully implemented. 1

Mineralocorticoid Receptor Antagonist Trials

• RALES (Randomized Aldactone Evaluation Study) evaluated spironolactone in NYHA class III-IV patients with HFrEF, demonstrating significant reductions in both morbidity and cardiovascular mortality when added to standard care. 2

• EPHESUS (Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study) assessed eplerenone in HF patients following acute myocardial infarction, showing substantial mortality benefit in this high-risk population. 2

• EMPHASIS-HF (Eplerenone in Mild Patients Hospitalization and Survival Study in Heart Failure) extended MRA evidence to patients with mild symptoms (NYHA class II), proving efficacy across the symptom spectrum and establishing MRAs as foundational therapy regardless of symptom severity. 2

Angiotensin Receptor-Neprilysin Inhibitor Evidence

• PARADIGM-HF compared sacubitril-valsartan (ARNI) to enalapril in HFrEF patients, establishing ARNIs as superior to ACE inhibitors for reducing cardiovascular death and HF hospitalization. 2

SGLT2 Inhibitor Trials in HFrEF

• DAPA-HF demonstrated that dapagliflozin 10 mg daily reduces worsening HF and cardiovascular death by 18% (HR 0.82) in HFrEF patients, with benefits independent of diabetes status. 3

• EMPEROR-Reduced showed empagliflozin significantly reduced the composite endpoint of cardiovascular death or HF hospitalization in HFrEF, establishing SGLT2 inhibitors as essential therapy across all HFrEF patients. 2

Beta-Blocker Evidence

• BBmeta-HF (Beta-blockers in Heart Failure Collaborative Group) performed a meta-analysis of 11 HF trials demonstrating that beta-blockers reduced all-cause and cardiovascular mortality in patients with reduced ejection fraction in sinus rhythm. 2

Additional HFrEF Trials

• CHARM (Candesartan in Heart failure-Assessment of Reduction in Mortality and morbidity) trials established that candesartan (an ARB) reduced cardiovascular death and HF hospitalization, providing evidence for ARB use when ACE inhibitors are not tolerated. 2

• SHIFT trial with ivabradine showed benefit in persistently symptomatic HFrEF patients with sinus rhythm, LVEF ≤35%, and resting heart rate ≥70 bpm despite optimal beta-blocker dosing. 2

Heart Failure with Preserved Ejection Fraction (HFpEF)

Unlike HFrEF, no single pharmacologic agent has definitively reduced mortality as a standalone endpoint in HFpEF, with current therapeutic goals focused on symptom relief, quality-of-life improvement, and hospitalization reduction. 3

SGLT2 Inhibitor Trials in HFpEF

• EMPEROR-Preserved demonstrated that empagliflozin 10 mg daily reduced the primary composite endpoint of time to HF hospitalization or cardiovascular death by 21% (HR 0.79) in patients with LVEF >40% and elevated natriuretic peptides, driven primarily by a 29% reduction in HF hospitalization rather than mortality. 2, 3

• DELIVER trial with dapagliflozin showed an 18% reduction in the composite of cardiovascular death or worsening HF in HFpEF patients, establishing SGLT2 inhibitors as Class 2a first-line disease-modifying therapy for all HFpEF patients regardless of diabetes status. 3

Angiotensin Receptor-Neprilysin Inhibitor Evidence

• PARAGON-HF (Prospective Comparison of ARNi with ARB Global Outcomes in HF with Preserved Ejection Fraction) showed no overall primary endpoint benefit in the broader HFpEF cohort, but subgroup analysis suggested benefit of sacubitril-valsartan versus valsartan in women and patients with LVEF 45-57% (rate ratio ≈0.73-0.78). 2, 3

Mineralocorticoid Receptor Antagonist Evidence

• TOPCAT (Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist) evaluated spironolactone in HFpEF and found no reduction in cardiovascular mortality but did show reduced HF-related hospitalization (HR 0.83), though major concerns were raised regarding trial conduct and regional differences. 2, 3

• CHARM-Preserved Trial assessed candesartan in patients with chronic HF and preserved LVEF, providing early evidence for RAAS blockade in this population. 2

Failed HFpEF Trials

• Multiple agents including perindopril, irbesartan, beta-blockers, nitrates, digoxin, ivabradine, and sildenafil have failed to demonstrate mortality benefit in HFpEF. 3

• RELAX trial with sildenafil (phosphodiesterase-5 inhibitor) showed no improvement in exercise capacity or clinical status in HFpEF patients. 2

Heart Failure with Mildly Reduced Ejection Fraction (HFmrEF)

Post-hoc analyses of HFrEF trials that included HFmrEF patients (LVEF 41-49%) suggest benefit from GDMT for HFrEF, though no dedicated prospective trials exist for this population. 2

• EMPEROR-Preserved subgroup of 1,983 patients with LVEF 41-49% showed empagliflozin reduced the primary composite endpoint of cardiovascular death or HF hospitalization, establishing SGLT2 inhibitors as Class 2a therapy for HFmrEF. 2

• PARAGON-HF subgroup analysis for patients with LVEF 45-57% suggested benefit of sacubitril-valsartan versus valsartan alone (rate ratio 0.78; 95% CI 0.64-0.95). 2

• TOPCAT post-hoc analysis of 520 patients with LVEF 44-49% showed spironolactone reduced the primary composite endpoint, mostly through cardiovascular mortality reduction among patients enrolled in North and South America. 2

• CHARM pooled data from 1,322 patients with LVEF 41-49% demonstrated candesartan reduced cardiovascular death, first HF hospitalization, and recurrent HF hospitalization. 2

Atrial Fibrillation Ablation in Heart Failure

Landmark AF Ablation Trials

• CASTLE-AF (Catheter Ablation versus Standard Conventional Treatment in Patients with Left Ventricular Dysfunction and Atrial Fibrillation) showed catheter ablation in HFrEF patients with AF resulted in reduced mortality (8% vs 18%) and hospitalization (31% vs 57%) compared to medical therapy at 70 months follow-up. 2

• PABA-CHF (Pulmonary Vein Antrum Isolation vs. AV Node Ablation with Bi-Ventricular Pacing) demonstrated 88% AF-free survival with catheter ablation and absolute LVEF increase of 8% at 6 months compared to pace-and-ablate strategy. 2

• AATAC-AF trial showed AF-free survival in the ablation arm versus 34% in the amiodarone arm, with significant improvements in LVEF (+8% vs +6%), mortality, hospitalization, and quality of life. 2

• CAMERA-MRI found 56% AF-free survival with ablation versus pharmacological rate control, with significant LVEF improvement (+18% vs +4%) and LVEF normalization ≥50% in 58% versus 9% of patients. 2

Key Implementation Insights

• Adverse events in GDMT trials occur in 75-85% of participants but show no significant difference between intervention and placebo arms, suggesting these reflect the high-risk nature of HF rather than medication-specific toxicity. 2

• Quality of life improvements are documented with ARBs, ARNIs, SGLT2 inhibitors, ivabradine, hydralazine-nitrate, and intravenous iron based on high-certainty evidence from landmark trials. 2

• Discontinuation of GDMT even after LVEF improvement leads to clinical deterioration and increased mortality, mandating continuation of therapy in patients with improved or recovered ejection fraction. 2, 1