A 72-year-old man presents with progressive dyspnea, orthopnea, and bilateral ankle swelling over 3 months. ECG shows low voltages in the limb leads despite marked left ventricular hypertrophy on echocardiogram (concentric LVH, LV wall thickness 16 mm). Serum free kappa/lambda ratio is elevated. Which is the most likely diagnosis?
- A AL (light chain) cardiac amyloidosis ✓
- B Fabry disease
- C Hypertensive heart disease
- D Hypertrophic cardiomyopathy due to sarcomere mutation
Correct answer: A. AL (light chain) cardiac amyloidosis
Explanation
The combination of LVH on echo with low voltage on ECG is the classic discordance that strongly suggests cardiac amyloidosis. Elevated serum free light chains (abnormal kappa/lambda ratio) point to AL amyloidosis, the most common systemic amyloid type affecting the heart. Hypertensive heart disease does not produce low voltages when LVH is present. HCM from sarcomere mutations typically shows voltage criteria for LVH on ECG.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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