How is low eGFR managed in patients with heart failure?

Management of Low eGFR in Heart Failure Patients

The management of low eGFR in heart failure patients should focus on addressing the underlying cardiorenal syndrome while optimizing guideline-directed medical therapy, with careful monitoring of renal function during treatment adjustments. 1

Understanding the Cause of Low eGFR in Heart Failure

Low eGFR in heart failure patients is primarily caused by:

1. Hemodynamic factors:

   • Reduced cardiac output leading to decreased renal perfusion
   • Increased central venous pressure causing renal venous congestion 1, 2
   • Right ventricular dilation impairing left ventricular filling 1

2. Neurohormonal activation:

   • Chronic activation of the renin-angiotensin-aldosterone system (RAAS) 1
   • Paradoxically low urine sodium excretion despite fluid overload 1

3. Medication effects:

   • Diuretics reducing intravascular volume and renal perfusion 1
   • RAAS inhibitors causing initial decline in GFR 3

Assessment of Patients with Heart Failure and Low eGFR

• Determine the type of cardiorenal syndrome (CRS):

  • Type 1: Acute heart failure causing acute kidney injury
  • Type 2: Chronic heart failure causing chronic kidney disease
  • Type 3: Acute kidney injury causing acute cardiac failure
  • Type 4: Chronic kidney disease causing chronic cardiac dysfunction 1

• Evaluate for:

  • Volume status (congestion vs. dehydration)
  • Medication effects (especially diuretics, RAAS inhibitors)
  • Other causes of kidney dysfunction:
    • Prostatic obstruction in older men
    • Nephrotoxic drugs (NSAIDs, certain antibiotics)
    • Renal artery stenosis (if sudden large drop in GFR) 1

Management Strategy

1. Optimize Volume Status

• For congestion:

  • Loop diuretics are first-line therapy
  • Consider higher doses in patients with very low GFR 1
  • Monitor urine sodium (uNa+) to assess diuretic response 1
  • Consider combination therapy with thiazide diuretics for diuretic resistance, but use with caution in patients with eGFR <30 mL/min 1

• For dehydration:

  • Reduce or temporarily hold diuretics
  • Consider careful volume repletion

2. Optimize Heart Failure Medications

• RAAS Inhibitors (ACEi/ARB/ARNI):

  • Continue despite initial decline in eGFR (up to 30-35% decline may still be associated with benefit) 3
  • Only discontinue if marked decline in renal function or severe hyperkalemia 1

• Mineralocorticoid Receptor Antagonists (MRAs):

  • For eGFR >50 mL/min/1.73m²: Start at 25mg daily
  • For eGFR 30-50 mL/min/1.73m²: Start at 25mg every other day
  • Monitor potassium levels closely 4

• SGLT2 Inhibitors:

  • Can be used in patients with eGFR ≥20 mL/min/1.73m² (empagliflozin) or ≥30 mL/min/1.73m² (dapagliflozin)
  • Provide long-term kidney protection despite initial small decline in eGFR
  • Do not require dose adjustment or up-titration
  • May reduce need for diuretic intensification 1

• Beta-blockers:

  • Generally safe in patients with renal dysfunction
  • Dose according to heart rate and blood pressure

3. Monitoring Strategy

• Regular monitoring of renal function:

  • Within 1-2 weeks after initiation or dose adjustment of RAAS inhibitors or diuretics
  • More frequent monitoring in patients with eGFR <30 mL/min/1.73m²
  • Monitor eGFR trajectory over time as a prognostic indicator 5

• Monitor electrolytes, especially potassium and sodium

• Assess for signs of worsening congestion or dehydration

Special Considerations

• Severe renal dysfunction (eGFR <30 mL/min/1.73m²):

  • Limited evidence from clinical trials
  • SGLT2 inhibitors have shown safety and efficacy down to eGFR of 20-30 mL/min/1.73m² 1, 6
  • Thiazide diuretics are less effective and should be used with caution 1

• Drug dosing considerations:

  • Higher doses of loop diuretics may be needed for similar effect in low eGFR 1
  • Certain renally excreted drugs may accumulate and require dose adjustment 1

• Avoid nephrotoxic medications:

  • NSAIDs and COX-2 inhibitors are contraindicated 1
  • Use caution with certain antibiotics

Key Pitfalls to Avoid

1. Discontinuing RAAS inhibitors prematurely due to modest, stable decline in eGFR
2. Underdosing diuretics in patients with severe renal dysfunction and congestion
3. Overlooking non-cardiac causes of worsening renal function
4. Failing to recognize that volume overload and right heart failure can cause renal dysfunction
5. Not adjusting monitoring frequency based on severity of renal dysfunction

By following this approach, clinicians can effectively manage low eGFR in heart failure patients while maintaining guideline-directed medical therapy to improve outcomes.