Finerenone Outperforms Spironolactone for Cardiorenal Protection in Moderate CKD

Background Information

Finerenone emerges as the safer choice for CKD patients.

Choosing the right MR antagonist in CKD affects outcomes and safety profiles significantly, impacting patient management. Finerenone reduced risks of all-cause death and progression of CKD with fewer instances of hyperkalemia compared to spironolactone. Spironolactone showed limited efficacy with high risks of hyperkalemia, while finerenone provided better outcomes, suggesting it as a safer option. Finerenone offers superior safety and efficacy in protecting cardiovascular and kidney function in CKD.

Confirmatory Impact 3/5

The review consolidates a robust finerenone evidence base (18,991-patient pooled analysis with significant mortality, HF, and CKD-progression benefits) against a clearly negative spironolactone trial, reinforcing existing KDIGO-aligned practice without providing the head-to-head data needed to be practice-changing.

Evidence Grade: Moderate

The underlying finerenone randomized data are high certainty, but the comparative conclusion is downgraded for indirectness (cross-trial and post-hoc comparisons of dissimilar populations) and the open-label design of the spironolactone trial.

Study Design

Current Opinion / narrative comparative review (not an original trial). It contrasts the BARACK-D open-label randomized trial of spironolactone with the FINE-HEART prespecified individual patient-level pooled analysis of three finerenone trials (FIDELIO-DKD, FIGARO-DKD, FINEARTS-HF), plus supporting data from the AMBER, DIAMOND, and ARTS trials and a 2020 Cochrane meta-analysis. No trial registration applies to the review itself; the authors report no funding beyond open-access support from HEAL-Link Greece.

Population

The review draws on distinct populations across cited trials. BARACK-D enrolled 1,434 English primary-care patients with stage 3b chronic kidney disease (CKD), mean age 74.8 ± 8.1 years, mean estimated glomerular filtration rate (eGFR) 43.5 mL/min/1.73 m², median albumin-to-creatinine ratio 1.5 mg/mmol (predominantly non-albuminuric), with 76.6% on background angiotensin-converting-enzyme inhibitor (ACEi) or angiotensin-receptor blocker (ARB). The FINE-HEART pooled analysis included 18,991 patients (mean age 67.0 ± 10.0 years); 83.6% had established CKD, 81.2% had type 2 diabetes (T2D), and 36.9% had heart failure (HF), with mean eGFR 58.9 ± 21.0 mL/min/1.73 m² and median urinary albumin-to-creatinine ratio 290 mg/g.

Baseline Characteristics

Primary Outcome Not Met

BARACK-D primary cardiovascular composite: all-cause death, HF hospitalization, stroke, transient ischemic attack, HF, or peripheral arterial disease (Median follow-up 3.0 years)

Statistical Methods

As a narrative review, no primary statistical analysis was performed. Cited data include HRs with 95% CIs from BARACK-D (open-label, blinded endpoint) and the FINE-HEART prespecified participant-level pooled analysis, between-group mean differences from an indirect comparison of AMBER versus FIDELIO/FIGARO subgroups, and RRs, standardized mean differences, and weighted mean differences from the 2020 Cochrane meta-analysis. Competing-risks handling, missing-data methods, and multiplicity corrections for the source trials were not detailed in the review.

Secondary Outcomes

Safety & Tolerability

⚠ = serious adverse event

Number Needed to Treat / Harm

Limitations

The review's central conclusion rests on indirect and post-hoc comparisons rather than any head-to-head hard-outcome trial. BARACK-D was open-label with predominantly non-albuminuric, elderly patients and lacked prespecified potassium-management strategies that might have preserved spironolactone exposure, potentially biasing against a drug that could not stay on therapy. The finerenone evidence base is confined largely to T2D-associated CKD and HF with preserved or mildly reduced ejection fraction, limiting direct extrapolation to non-diabetic CKD.

Clinical Interpretation

The individual trial and pooled datasets are strong (large, randomized, mostly double-blind for finerenone), but the comparative claim between agents is supported only by indirect evidence and cross-trial contrasts of dissimilar populations. It can be concluded that finerenone has proven cardiorenal outcome benefit with manageable hyperkalemia risk and that spironolactone failed its cardiovascular endpoint in moderate non-albuminuric CKD; it cannot be concluded that finerenone is superior to spironolactone on hard outcomes in a matched population, since no head-to-head trial exists. The authors' preference for finerenone is a reasoned opinion, explicitly acknowledged as based on inconclusive comparative data.

Clinical Pearls

Pharmacist Implications

• For patients with type 2 diabetes and albuminuric CKD, favor finerenone for guideline-supported cardiorenal protection; reserve spironolactone primarily for patients with CKD and difficult-to-control hypertension where greater BP lowering is the goal.
• Recognize that spironolactone's active metabolites accumulate when eGFR falls below 45 mL/min/1.73 m², prolonging effect and raising the risk of acute kidney function decline and hyperkalemia; finerenone lacks active metabolites and has a 2–3 hour half-life.
• Anticipate hyperkalemia with either agent, but counsel that permanent discontinuation for hyperkalemia with finerenone is uncommon (about 1.3%); do not abandon therapy at the first potassium bump without a management plan.
• Consider potassium binders (patiromer, sodium zirconium cyclosilicate) and SGLT2 inhibitors as enabling strategies when spironolactone is needed but hyperkalemia limits use, as demonstrated in the AMBER trial.
• Verify baseline potassium and eGFR before initiating any MRA and re-check within the first weeks; the highest-risk discontinuation window in BARACK-D was the first 6 months.

Guideline Context

The discussion aligns with the KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of CKD, which endorses finerenone for cardiorenal protection in patients with T2D-associated CKD and albuminuria on maximally tolerated renin-angiotensin system inhibition. The BARACK-D result reinforces that steroidal MRAs lack proven hard-outcome cardiovascular benefit in moderate non-albuminuric CKD, consistent with prior low-to-moderate certainty evidence.

Monitoring Guidance

Monitor serum potassium and eGFR at baseline, within 4 weeks of initiation or dose change, and periodically thereafter. For finerenone, initiation generally requires potassium 5.0 mmol/L or lower; withhold or reduce dose if potassium exceeds 5.5 mmol/L. Watch for acute eGFR decline (the leading cause of spironolactone discontinuation in BARACK-D) and, with spironolactone specifically, gynecomastia and other antiandrogenic effects.

Nuanced Considerations

BARACK-D enrolled an older, largely non-albuminuric population, whereas finerenone's benefit is strongest in albuminuric diabetic CKD; the two evidence bases are not directly comparable. Spironolactone showed a larger BP-lowering effect in the indirect resistant-hypertension comparison (systolic reduction 11.7 mmHg for spironolactone plus patiromer vs 7.1 mmHg for finerenone), suggesting a preserved role where BP control drives therapy. Finerenone's cardiovascular benefit is mediated mainly through reduced HF hospitalization rather than atherosclerotic events.

Controversies & Gaps

No head-to-head randomized trial compares finerenone and spironolactone on hard cardiorenal outcomes, and the authors explicitly call for one. Whether spironolactone would show benefit if potassium-management strategies enabled sustained exposure remains untested. The differential effect on stroke (a signal for spironolactone in observational data) versus HF hospitalization (finerenone) is unresolved, and the DIAMOND trial's inability to answer whether potassium-binder-enabled RAAS optimization improves outcomes leaves a persistent gap.

Cost & Logistics

The review notes spironolactone is off-patent and inexpensive, and finerenone remains commercially unavailable in some countries, creating socioeconomic rationale for a comparative trial. Cost differentials favor spironolactone particularly in low-income settings; access to finerenone and to enabling potassium binders may limit implementation of the preferred strategy.

Editor's Note

This is an author opinion/review, not original trial data; the superiority claim for finerenone over spironolactone rests on indirect and post-hoc comparisons, which the authors themselves label inconclusive. All quantitative figures are extracted from cited trials (BARACK-D, FINE-HEART, AMBER, ARTS) as reported in the review rather than from primary sources. Editors should verify effect estimates against the original publications if reproduced.

Full text source: PubMed Central (Open Access)