Cardiorenal Considerations: 5 Pearls Segment

Core IM

Cardiorenal syndrome (CRS) is becoming increasingly recognized with the growing number of patients with concomitant congestive heart failure and chronic kidney disease. Management of these patients both in the inpatient and outpatient settings is challenging especially as the evidence base continues to expand rapidly. This episode aims to review more recent evidence and developments in the understanding of cardiorenal syndrome, inpatient diuretic management, and use of cardio- and renoprotective medical therapies in heart failure patients with chronic kidney disease.

On this Core IM episode, learners will better understand the differences in characteristics between loop diuretics, how to properly assess diuretic response in patients admitted with decompensated heart failure, when to use adjunctive agents including thiazides and acetazolamide, and the appropriate use of renoprotective and guideline-directed medical therapy in later stages of chronic kidney disease.  You’re invited to join the team as they discuss, Cardiorenal Considerations: 5 Pearls Segment

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Pearl 1: Make sure the renal dysfunction is actually all cardiorenal!

• How do you define cardiorenal physiology?

  • Classic Definition:
    •  Kidney dysfunction that is related to either a (1) low-flow state and/or (2) renal venous congestion
      • BOTH can independently lead to decreased intrarenal blood flow
      •  BOTH can lead to neurohormonal activation → Increased renin-angiotensin-aldosterone system (RAAS) activity
        • Can be detrimental to renal function!
      • NOTE: Renal venous congestion is thought to be a larger contributor to kidney dysfunction than low-flow states

• How should you think about the differential for a kidney injury in someone with heart failure?

  • Be broad! Multiple processes can happen at the same time
    • Urinalysis findings:
      • Pure cardiorenal syndrome
        • “Bland” with no protein, blood, granular or other cell casts
          • May have hyaline casts
          • No signs of intrinsic injury!
      • NOTE: Screen for proteinuria in heart failure patients!
        • Urine protein to creatinine ratio (UPCR) or
        • Urine albumin to creatinine ratio (UACR)
    • Dilute urine can falsely lower proteinuria on a urine dipstick!

Pearl 2: Practical Tidbits on Loop Diuretics

  • What is the “go-to” loop diuretic for someone who is hospitalized for volume overload?
  • What are the differences between loop diuretics?
    • IV formulations:
      • Furosemide vs. Bumetanide
        • No difference in outcomes demonstrated
          • But not largely studied!
        • Bumetanide Considerations:
          • More potent
            • Practitioners may be more comfortable with using higher equivalent doses since bumetanide doses are in the single digits
          • Severe myalgias with IV bumetanide as a continuous infusion
            • Especially with higher doses
            • Unclear if unique to bumetanide or if purely dose-related given furosemide is not typically used at equally high equivalent doses
    • PO formulations:

Pearl 3: Assessing Diuretic Response and Renal Function

  • How to assess diuretic response?
  • What do you do if the response to diuretic is not adequate?
  • What happens to creatinine during diuresis?
    • Generally safe to see up to 30% rise in from baseline levels with active decongesion
      • Known as “rise in serum creatinine” (RSC) or”worsening renal function” (WRF) ( 0pubmed)
        • Usually does NOT reflect true renal tubular injury ( 0pubmed)
          • Even though this threshold is how acute kidney injury (AKI) is defined
        • Rise is a result of:
          • Hemodynamic or functional change in glomerular filtration
          • Hemoconcentration of creatinine ( 0pubmed)
            • In patients who are being adequately decongested ( 0pubmed)!
        • Alone, should NOT be a reason to stop diuresing a volume overload patient
        • The rise has no predictive value for rehospitalization or mortality ( 0pubmed) unless patients also had other signs of congestion at discharge
      • Still, always still do the due diligence each day!
        • Volume assessment
        • Urine output monitoring
        • Consider need to evaluate for another cause of rising serum creatinine
        • Consider more sophisticated and/or invasive measures of volume status
          • Point-of-care ultrasound (POCUS)
          • Right heart catheterization

Pearl 4: How to approach diuretic resistance

  • What is diuretic resistance?
  • Consider…Is something else going on?
    • Diuretics cannot work if they are not reaching the kidney!
    • Some factors to consider:
      • Shock
      • Low-flow state
      • Elevated intra-abdominal pressure (ascites)
  • How can you augment your diuresis?
    • Sequential nephron blockade!
      • Thiazide or Thiazide-Like Diuretics:
        • PO Metolazone vs. IVChlorothiazide (or Diuril)
        • Alternative adjusts:
          • Hydrochlorothiazide or Chlorthalidone
            • Reasonable options though more in outpatient setting
              • Commonly used as antihypertensives
          • Acetazolamide
          • Acute SGLT2i
            • Not well-established adjunct
          • Hypertonic saline
            • Not well-established adjunct
    • What should be monitored during diuresis?
      • Electrolytes, particularly hypokalemia
        • More common with augmentation
        • Hypokalemia is an independent risk factor for development of diuretic resistance
          • Add potassium-sparing diuretics early!
            •  Long-term benefit
      • Volume Depletion
    • What about ultrafiltration (UF)?
      • CARRESS-HF Trial
      • In practice: UF only after a failing maximal medical therapy
        • Due to concerns about future renal function when starting HD and dialysis access complications

Pearl 5: Don’t be afraid of medical therapy because of CKD


Shreya Trivedi, MD, ACP Member – Host, Editor
Andrew Ling, MD – Host, Editor, MOC questions
Nayan Arora, MD* - Guest
Nicole Bhave, MD *- Guest


Nisha Bansal, MD, FACP
Larissa Kruger Gomes, MD

* Nayan Arora, MD:  AstraZeneca, Bayer – Consultant 

* Nicole Bhave, MD:  Rednvia - Consultant

Those named above, unless otherwise indicated, have no relevant financial relationships to disclose with ineligible companies whose primary business is producing, marketing, selling, re-selling, or distributing healthcare products used by or on patients.  All relevant relationships have been mitigated.

Release Date:  May 13, 2024 

Expiration Date: May 12, 2027 

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This activity has been planned and implemented in accordance with the accreditation requirements and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint providership of the American College of Physicians and Core IM.  The American College of Physicians is accredited by the ACCME to provide continuing medical education for physicians.

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