Key Points
- Cardiac amyloidosis -- including both AL (light chain) and ATTR subtypes -- is an underdiagnosed cause of heart failure with preserved ejection fraction (HFpEF); this case ultimately confirmed AL amyloidosis of the lambda variety
- Ejection fraction is a profoundly misleading metric in infiltrative cardiomyopathies; a "normal" EF can mask critically reduced cardiac output
- Congestive hepatopathy from cardiac amyloidosis can mimic cirrhosis on CT imaging, leading to diagnostic misdirection
- Ascitic fluid analysis -- specifically the combination of high SAAG (≥1.1) and high fluid protein (≥2.5 g/dL) -- provides a critical physiologic clue pointing toward cardiac rather than hepatic etiology
- Right heart catheterization revealed cardiogenic shock-range hemodynamics (CI 1.15 L/min/m2, RA 23 mmHg) completely hidden by the EF of 55%
- Tragic outcome: The patient died from sudden cardiac arrest while undergoing staging PET scan -- the hemodynamic severity documented on RHC presaged high risk of sudden arrhythmic death
1. Case Presentation
Presenting History
A 75-year-old male with no known liver disease risk factors presented with progressive abdominal distension and refractory ascites. He had no history of alcohol use, viral hepatitis, nonalcoholic steatohepatitis, or autoimmune liver disease. Notably, he had no lower extremity edema despite massive ascites -- an atypical finding.
Initial Workup
Imaging
- CT abdomen: Micronodular liver changes, multiple hepatic cysts, findings reported as "cirrhosis with portal hypertension"
- Echocardiogram: EF 55%, RVSP 40 mmHg
Laboratory Data
- Total bilirubin: 1.7 mg/dL
- Serum albumin: 4.0 g/dL
- Serum total protein: 6.8 g/dL
- INR: ~4.0 (on chronic warfarin therapy)
Paracentesis
- Volume removed: 5.7 liters (rapid reaccumulation)
- Ascitic fluid protein: 3.6 g/dL (repeat: 4.1 g/dL)
- Ascitic fluid albumin: 2.3 g/dL
- Calculated SAAG: 1.7 g/dL
Diuretic Regimen (Refractory)
- Bumetanide 4 mg PO BID (~320 mg furosemide equivalent)
- Dapagliflozin 10 mg daily
- Spironolactone 50 mg daily
The Diagnostic Pivot
The hepatology service evaluated the patient and concluded the ascites was cardiac in origin despite the seemingly reassuring echocardiogram. A right heart catheterization was performed.
Right Heart Catheterization
| Parameter | Value | Normal Range |
|---|---|---|
| Right atrial pressure (RA) | 23 mmHg | 0-8 mmHg |
| RV pressure | 43/25 mmHg | 15-30/0-8 mmHg |
| Pulmonary artery pressure | 54/34 mmHg | 15-30/4-12 mmHg |
| Pulmonary capillary wedge pressure | 28 mmHg | 4-12 mmHg |
| Cardiac output | 2.66 L/min | 4.0-8.0 L/min |
| Cardiac index | 1.15 L/min/m2 | 2.5-4.0 L/min/m2 |
| RA oxygen saturation | 64% | 65-75% |
| PA oxygen saturation (SvO2) | 65% | 65-75% |
The Hemodynamic Revelation
An EF of 55% with a cardiac index of 1.15 L/min/m2 represents cardiogenic shock-range low output masked by a preserved ejection fraction. The RA pressure of 23 mmHg fully explains the massive, diuretic-refractory ascites and congestive hepatopathy.
Hemodynamic Calculation Walkthrough
Summary of Derived Hemodynamic Parameters
| Parameter | Result | Normal | Clinical Significance |
|---|---|---|---|
| mPAP | 40.7 mmHg | 10-20 | Confirms PH (moderately severe) |
| TPG | 12.7 mmHg | <12 | Pre-capillary component present |
| PVR | 4.8 WU | 0.25-1.6 | Confirms CpcPH |
| PAC | 1.65 mL/mmHg | >2.3 | Reduced; stiff pulmonary vasculature |
| Stroke volume | ~33 mL | ~70 mL | Explains EF-CO dissociation |
| Estimated EDV | ~60 mL | ~120 mL | Stiff ventricle cannot fill |
| Forrester profile | Profile C | A | "Cold and wet" -- worst subset |
Warning: PAH Vasodilators Contraindicated
Despite PVR of 4.8 WU, this is Group 2 PH, NOT Group 1 PAH. Endothelin receptor antagonists, PDE5 inhibitors, and prostanoids are contraindicated -- they increase pulmonary blood flow into an already congested left heart, worsening pulmonary edema and heart failure without reducing mortality.
2. The Diagnostic Red Herrings
Red Herring #1: The CT "Cirrhosis"
The CT findings of micronodular liver changes were initially interpreted as cirrhosis. However, chronic hepatic venous congestion from elevated right-sided pressures can produce cardiac pseudo-cirrhosis -- a nodular liver appearance caused by centrilobular necrosis and patchy regeneration that mimics true cirrhotic remodeling on imaging.
Red Herring #2: The "Normal" Ejection Fraction
The echocardiographic EF of 55% created a false sense of reassurance. This is the single most important barrier to timely diagnosis of cardiac amyloidosis worldwide.
EF-CO Dissociation Explained
- Normal heart: fills 120 mL, ejects 80 mL --> EF 67%
- Amyloid heart: fills 50 mL, ejects 28 mL --> EF 55%
The EF appears nearly identical, but the cardiac output is catastrophically different.
Key statistics on diagnostic delay from the literature:
- Median diagnostic delay: 13 months from first HF manifestation to amyloidosis diagnosis (IQR 2-47 months)
- 44% of cardiac amyloidosis patients were initially misdiagnosed
- Only 10% of physicians perform systematic screening of HFpEF patients for cardiac amyloidosis
- ATTR deposition found in 13-17% of patients carrying a diagnosis of HFpEF
Red Herring #3: The INR as "Liver Failure"
The INR of ~4.0 on warfarin reflects pharmacologic vitamin K antagonism, not hepatic synthetic failure. In anticoagulated patients, rely on albumin and factor V for synthetic function assessment.
Red Herring #4: Massive Ascites Without Pedal Edema
Preferential splanchnic fluid accumulation with dry legs is a characteristic pattern of right heart failure from restrictive cardiomyopathy -- not a finding that excludes cardiac disease.
Red Herring #5: Diuretic Resistance
When bumetanide 4 mg PO BID plus dapagliflozin and spironolactone cannot prevent ascites reaccumulation, the problem is not inadequate diuretic dosing -- it is inadequate cardiac output and overwhelming venous congestion.
Clinical Pearl
When you encounter a patient with ascites, always ask three questions: (1) Is the SAAG high or low? (2) Is the fluid protein high or low? (3) Does the clinical context match? The combination of high SAAG + high protein should immediately prompt evaluation for cardiac disease, hepatic venous outflow obstruction, or other non-cirrhotic causes of portal hypertension.
3. Diagnostic Confirmation: AL (Lambda) Cardiac Amyloidosis
Free Light Chain and Monoclonal Protein Results
| Test | Result | Reference / Threshold | Significance |
|---|---|---|---|
| Kappa free light chain | 5.31 mg/dL (53.1 mg/L) | 3.3-19.4 mg/L | Mildly elevated |
| Lambda free light chain | 28.5 mg/dL (285 mg/L) | 5.7-26.3 mg/L | Markedly elevated |
| Kappa/Lambda FLC ratio | 0.1863 | 0.26-1.65 | Markedly suppressed -- confirms clonal lambda excess |
| M-protein isotype | IgA lambda | -- | Tiny intact IgA lambda monoclonal protein |
| M-protein GL | <0.010 g/dL | -- | Essentially undetectable as intact immunoglobulin |
dFLC (the staging number)
dFLC = Involved (lambda) - Uninvolved (kappa) = 285 - 53.1 = 231.9 mg/L
Mayo threshold: ≥180 mg/L. This patient exceeds the threshold despite an M-protein so small it barely registered.
Tc-99m PYP Scintigraphy
The patient was referred to a tertiary academic center for Tc-99m PYP scintigraphy. Result: NEGATIVE -- Grade 0 uptake. This definitively excluded ATTR-CM as the diagnosis.
Diagnostic Synthesis
The combination of a positive lambda monoclonal protein screen and a negative PYP scan confirmed AL (lambda) cardiac amyloidosis. Per the Gillmore 2016 algorithm, a negative PYP scan with positive monoclonal protein directs toward AL amyloidosis, which requires tissue confirmation and hematologic evaluation.
Urine Studies -- A Critical Nuance
| Test | Result | Interpretation |
|---|---|---|
| Microalbumin/Creatinine ratio | 139 mg/g creat (H) | Microalbuminuria range -- true glomerular leak |
| Protein/Creatinine ratio | 0.73 (H) | Mildly elevated -- not normal, not nephrotic |
The protein/creatinine ratio of 0.73 is not normal (normal <0.2). The kidneys were whispering while the heart was screaming. However, a P/Cr of 0.73 is far below nephrotic range (>3.5), and the clinical presentation was dominated entirely by the cardiac syndrome.
Red Herring #6: Absent Nephrotic Syndrome
Warning: "No Nephrotic Syndrome, Therefore Not AL Amyloidosis" -- A Lethal Cognitive Error
The absence of nephrotic syndrome should never be used to lower clinical suspicion for AL amyloidosis in a patient with unexplained restrictive cardiomyopathy. Cardiac-predominant lambda AL amyloidosis with a normal urinalysis is a recognized, distinct phenotype that constitutes up to 25-30% of AL amyloidosis presentations.
Why Lambda Light Chains Are Cardiotrophic
Tissue tropism in AL amyloidosis is determined by the variable domain sequence of the light chain -- specifically the CDR1 and CDR3 loops. Lambda light chains encoded by certain germline gene segments show preferential cardiac tropism:
- V-lambda-1 and V-lambda-6 gene segments -- strongly associated with cardiac amyloidosis, often with minimal renal involvement
- V-lambda-2 and V-lambda-3 gene segments -- more nephrotrophic; higher rates of glomerular deposition and nephrotic syndrome
- Kappa light chains -- more commonly nephrotrophic overall; isolated cardiac kappa AL is relatively uncommon
4. Anticipated Treatment
Note: This section reflects treatment that would have been initiated had the patient survived to receive it. The patient died before systemic therapy could be started.
Standard of Care: Dara-VCd
The ANDROMEDA trial established daratumumab-bortezomib-cyclophosphamide-dexamethasone (Dara-VCd) as the standard first-line treatment for AL amyloidosis, with hematologic VGPR+ in 79% of patients vs. 49% with VCd alone. The depth of hematologic response correlates directly with organ (cardiac) response and survival.
For a patient with this hemodynamic profile (CI 1.15, RA 23), treatment would require careful dose modifications for hemodynamic fragility, avoidance of carfilzomib (cardiotoxic), and avoidance of melphalan-based ASCT conditioning.
Heart Failure Management Considerations
Warning: Standard HFpEF Medications in Cardiac Amyloidosis
- Beta-blockers and calcium channel blockers may be harmful. The stiff amyloid ventricle is rate-dependent for cardiac output -- slowing heart rate further reduces already compromised output.
- ACE inhibitors/ARBs may cause significant hypotension due to autonomic neuropathy and reduced preload sensitivity
- Digoxin binds to amyloid fibrils, potentially causing toxicity at therapeutic levels
Emerging and Investigational Therapies
| Therapeutic Class | Mechanism | Status | "Cure" Potential |
|---|---|---|---|
| TTR stabilizers (tafamidis, acoramidis) | Prevent tetramer dissociation | FDA-approved | No -- slows progression |
| Gene silencers (vutrisiran, patisiran) | Reduce hepatic TTR production 80-90% | Approved (polyneuropathy); HELIOS-B positive for CM | Partial -- stops production |
| CRISPR gene editing (NTLA-2001) | Permanent TTR gene knockdown (>90%) | Phase 2/3 | Partial -- single dose |
| Anti-amyloid antibodies (NI006) | Phagocytic removal of deposited fibrils | Phase 3 | Highest -- direct removal demonstrated |
| Combination (stabilizer/silencer + depleter) | Halt production + remove deposits | Theoretical/preclinical | Greatest potential |
5. Nephrology-Specific Considerations
This patient exemplifies Type 1 cardiorenal syndrome -- acute/chronic cardiac dysfunction leading to renal impairment. The cardiac index of 1.15 L/min/m2 produces critical renal hypoperfusion, which limits diuretic delivery, activates RAAS and the sympathetic nervous system, promotes sodium and water retention, and creates the observed diuretic resistance.
The patient's renal impairment was driven by hemodynamic compromise (cardiorenal syndrome), not glomerular amyloid deposition. The absence of significant proteinuria confirms the glomerular filtration barrier was structurally intact.
6. Clinical Outcome
Patient Deceased
The patient died from sudden cardiac arrest while undergoing a staging FDG-PET scan as part of the AL amyloidosis workup. The patient had not yet received any disease-modifying therapy for confirmed AL amyloidosis at the time of death.
Clinicopathologic Correlation
The death was hemodynamically predictable. The right heart catheterization had established:
- Cardiac index 1.15 L/min/m2 -- cardiogenic shock-range forward output
- RA pressure 23 mmHg -- severe right-sided congestion
- SvO2 65% -- tissue oxygen extraction at the lower limit of compensated reserve
- Forrester Profile C -- the hemodynamic subset with the highest mortality
Patients with AL cardiac amyloidosis at this stage are at extreme risk for malignant arrhythmia. The amyloid-infiltrated myocardium creates a substrate for VT/VF through mechanical stretch, autonomic neuropathy, patchy amyloid creating heterogeneous conduction, and ischemia from microangiopathy.
The ICD Question
ICDs are generally NOT recommended in AL cardiac amyloidosis. The predominant mode of death is electromechanical dissociation (EMD/PEA), not shockable VF. A 2022 analysis found that among AL patients who received ICDs, fewer than 30% had shockable rhythms as their terminal event.
Clinical Pearl
In AL cardiac amyloidosis, sudden cardiac death risk is high, but ICD placement does not reliably prevent it because EMD/PEA is the dominant mechanism. Wearable defibrillators may have a role as a bridge during hematologic treatment response, but their utility is unproven.
7. Summary and Teaching Points
- EF is a fraction, not a measure of cardiac output. In restrictive cardiomyopathy, a preserved EF can mask critically low cardiac output. When the clinical picture is worse than the echo suggests, pursue invasive hemodynamic assessment.
- CT "cirrhosis" requires clinical correlation. Congestive hepatopathy can produce imaging findings indistinguishable from true cirrhosis. When there are no risk factors for liver disease and synthetic function is preserved, question the radiographic diagnosis.
- Ascitic fluid protein is a window into sinusoidal physiology. High-protein ascites (≥2.5 g/dL) with high SAAG (≥1.1) points to cardiac congestion through intact sinusoidal fenestrations rather than cirrhotic capillarization.
- The INR on anticoagulation is not a measure of liver function. Rely on albumin and factor V for synthetic function assessment in anticoagulated patients.
- Massive ascites with minimal pedal edema suggests cardiac, not cirrhotic, etiology.
- Diuretic resistance quantifies hemodynamic severity. When triple nephron blockade cannot prevent ascites reaccumulation, the problem is inadequate cardiac output, not inadequate diuretic dosing.
- Think amyloid in elderly patients with HFpEF. Particularly in males over 65 with unexplained HFpEF and increased wall thickness.
- The PYP scan is the diagnostic linchpin -- but it must be interpreted in context. A negative PYP scan with a positive monoclonal protein screen correctly redirects from ATTR-CM to AL cardiac amyloidosis.
- AL cardiac amyloidosis kills faster than ATTR. The full diagnostic panel should be initiated simultaneously, not sequentially.
- Treatment changes outcomes. The therapeutic landscape is evolving toward potential disease reversal, with anti-amyloid antibodies demonstrating actual amyloid removal from the myocardium on imaging.
References
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- Kittleson MM, Ruberg FL, Ambardekar AV, et al. 2023 ACC expert consensus decision pathway on comprehensive multidisciplinary care for the patient with cardiac amyloidosis. J Am Coll Cardiol. 2023;81(11):1076-1126. PubMed
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Case prepared for educational purposes. All patient identifiers have been removed.
© Urine Nephrology Now | Clinical Mastery Series
Andrew Bland, MD, MBA, MS