CardiovascularCorner

1. Name of pattern and its associated syndrome?
2. Management:

CARDIAC AMYLOIDOSIS: A STEP-BY-STEP DIAGNOSTIC ALGORITHM

Cardiac amyloidosis is frequently overlooked because its presentation can resemble hypertensive heart disease, HFpEF or hypertrophic cardiomyopathy.

The critical first step is distinguishing AL (light-chain) amyloidosis from ATTR (transthyretin) amyloidosis.

Here is a practical approach.

1. Recognise the red flags

Suspect cardiac amyloidosis in patients with:
- Unexplained increased LV wall thickness.
- HFpEF, particularly with right-sided heart failure.
- Low ECG voltage despite increased ventricular wall thickness.
- Bilateral carpal tunnel syndrome, lumbar spinal stenosis or spontaneous biceps tendon rupture.
- Aortic stenosis with paradoxical low-flow, low-gradient physiology.
- Apical sparing on longitudinal strain imaging.
- Persistently elevated troponin or disproportionately elevated NT-proBNP.

2. Screen for a monoclonal protein FIRST

This is the most important step in the diagnostic pathway.

Order all three:
- Serum free light chains (sFLC), including the kappa/lambda ratio.
- Serum immunofixation electrophoresis.
- Urine immunofixation electrophoresis.

Important: Serum protein electrophoresis (SPEP) alone is NOT sufficient to exclude AL amyloidosis.

Interpret free light chains in the context of renal function.

3. What if monoclonal protein testing is abnormal?

Refer for urgent haematology assessment.

A positive result raises suspicion for AL amyloidosis but does not establish the diagnosis.

Proceed to tissue biopsy, using an appropriate site:
- Abdominal fat pad.
- Bone marrow.
- Clinically involved organ.
- Endomyocardial biopsy when indicated.

Congo red staining demonstrates amyloid deposits. Protein typing by mass spectrometry is preferred; validated immunohistochemistry may also be used.

Do not assume that a positive monoclonal screen automatically means AL. ATTR can coexist with MGUS.

4. What if monoclonal protein testing is normal?

Proceed to bone-avid tracer scintigraphy:
- ⁹⁹ᵐTc-PYP.
- ⁹⁹ᵐTc-DPD.
- ⁹⁹ᵐTc-HMDP.

SPECT imaging is essential to confirm that uptake is truly within the myocardium rather than blood pool activity.

5. Interpret the scan
- Grade 0: No myocardial uptake.
- Grade 1: Uptake less than bone.
- Grade 2: Uptake equal to bone.
- Grade 3: Uptake greater than bone.

Grade 2 or 3 myocardial uptake, confirmed by SPECT, in the absence of a monoclonal protein supports a non-biopsy diagnosis of ATTR cardiac amyloidosis.

Grade 1 is equivocal and requires further evaluation.
A negative scan does not completely exclude ATTR when clinical suspicion remains high, particularly in early disease or certain TTR variants.

6. Confirm the amyloid subtype

Once ATTR is diagnosed, perform TTR gene sequencing.
- Pathogenic variant detected: hereditary ATTR (ATTRv).
- No pathogenic variant: wild-type ATTR (ATTRwt).

Genetic counselling should be offered.

7. Do not forget disease staging
Once AL amyloidosis is confirmed, assess disease burden and cardiac involvement using:

- NT-proBNP or BNP.
- Cardiac troponin.
- Estimated glomerular filtration rate (eGFR).

These biomarkers contribute to prognostic assessment and treatment planning.

THE MOST IMPORTANT CLINICAL LESSON

Never diagnose ATTR cardiac amyloidosis from a positive PYP scan alone.

First exclude a monoclonal protein using serum free light chains, serum immunofixation and urine immunofixation.

Missing AL amyloidosis can delay urgent, potentially life-prolonging treatment.

References:

1. ASH 2026 Guidelines on Diagnosis of Light Chain Amyloidosis.
2. Kittleson MM et al. 2023 ACC Expert Consensus Decision Pathway on Cardiac Amyloidosis. J Am Coll Cardiol. 2023;81:1076–1126.

58 yo female with chest pain 2 days ago.
What's the most likely diagnosis ⁉️

Echo From Scratch | Post #55

Measuring the LV with M-mode

M-mode provides high temporal resolution and allows precise linear measurements of the left ventricle.

But timing is everything.

Diastolic measurements: Taken at the Q wave of the simultaneous ECG:
- LVIDd: LV internal diameter in diastole
- IVSd: Interventricular septal thickness in diastole
- PWTd: Posterior wall thickness in diastole

Systolic measurements: Taken at maximum posterior motion of the interventricular septum, provided septal motion is normal:

- LVIDs: LV internal diameter in systole
- IVSs: Septal thickness in systole
- PWTs: Posterior wall thickness in systole

Clinical relevance
These measurements help assess LV dimensions, wall thickness and calculate LV mass. They can also contribute to selected estimates of systolic function.

Remember: M-mode measurements are only reliable when the cursor is correctly aligned using 2D imaging. For routine EF assessment, biplane Simpson’s method or 3D echocardiography is preferred.

Which finding is characteristic of Propofol Infusion Syndrome?
A. Hypokalemia
B. Metabolic alkalosis
C. Rhabdomyolysis
D. Hypercalcemia