NY Cardiovascular Symposium Case Study Question
A 82 year old woman is admitted for progressive shortness of breath. Her examination reveals a BP 126/66 mm Hg, HR 96, regular. Macroglossia is present. Bibasilar crackles are present. The PMI is discrete and a loud S4 gallop is audible. Her JVP > 12 cm and there is 2+ pitting edema. ECG: NSR, low QRS voltage, diffuse T wave flattening
BUN: 46 mg/dL creatinine: 3.1 mg/dL NT-proBNP: 8600 pg/ml
Echocardiogram: LVEF 62%, wall thickness 18 mm, marked left atrial enlargement and a restrictive diastolic filling pattern.
What would be the most appropriate initial diagnostic test:
- Serum free light chain assay
- Serum protein electrophoresis (SPEP) measurement
- Technetium pyrophosphate cardiac imaging
- Cardiac magnetic resonance imaging with gadolinium
Correct Answer: A
Rationale: The clinical picture is most consistent with heart failure with preserved ejection fraction (HF-pEF) due to a restrictive cardiomyopathy. The patient's age and macroglossia should suggest AL amyloidosis. The sensitivity and specificity of quantitative serum free light chain measurement is substantially better than SPEP measurement. Pyrophosphate cardiac imaging is useful for assessing wild type transthyretin amyloidosis but is not helpful for detecting AL cardiac disease. Cardiac MRI should normally be considered but the patient has significant renal dysfunction and the use of gadolinium is contraindicated.
References: Falk RH. AL (Light-chain) cardiac amyloidosis. A review of diagnosis and therapy. J Am Coll Cardiol 2016;68:1323-41