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Non-invasive ATTR Diagnosis — EECC MCQ

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ModerateCardiac ImagingNon-invasive ATTR DiagnosisEECC

A 50-year-old man with suspected cardiac amyloidosis undergoes technetium-99m DPD bone scintigraphy. The scan shows Grade 3 cardiac uptake (uptake greater than bone). Serum free light chains and immunofixation are normal. Is endomyocardial biopsy needed?

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Correct answer: D — No — Grade 2 or 3 DPD uptake with negative serum and urine monoclonal protein studies is diagnostic of ATTR cardiac amyloidosis without the need for biopsy (≥99% positive predictive value)

The Gillmore et al. (2016) landmark study established that technetium-99m DPD/HMDP/PYP bone scintigraphy with Grade 2-3 cardiac uptake, combined with absent monoclonal protein on serum free light chains AND serum/urine immunofixation, has a positive predictive value of ≥99% for ATTR cardiac amyloidosis — rendering endomyocardial biopsy unnecessary. This non-invasive diagnostic algorithm has been endorsed by the 2023 ESC Cardiomyopathy Guidelines (Class I recommendation). Crucially, monoclonal protein studies MUST be negative — if positive, biopsy is required to exclude AL amyloidosis (which can show false-positive DPD uptake in ~20% of cases). Grade 1 uptake (less than bone) is indeterminate and may require biopsy.

Reference: ESC (2023): Guidelines on Cardiomyopathies; Gillmore et al., Circulation 2016