https://orcid.org/0000-0002-2249-1299
A 70-year-old male with hypertension presented with dyspnoea and bilateral leg oedema. He had a prior bilateral carpal tunnel release surgery and back surgery for spinal stenosis. Electrocardiogram showed normal sinus rhythm and QRS voltage. Echocardiography showed severe concentric left ventricular hypertrophy, right ventricular hypertrophy, and apical sparing pattern (Supplementary material online, Video S1). A cardiac magnetic resonance imaging scan showed diffuse subendocardial and transmural enhancement on late gadolinium enhancement imaging (Supplementary material online, Video S2). Outside images of bone scintigraphy were reviewed showing no tracer uptake in the myocardium [Panel A, grade 0 uptake on planar, no myocardial uptake with tracer in the blood pool on SPECT/CT (single-photon emission computed tomography/ computed tomography)]. Brain natriuretic peptide was 71 pg/mL. Troponin I was 0.06 ng/mL. Serum and urine immunofixation electrophoresis and serum-free light chains were all within normal limits. We suspected either a false-negative bone scan or issues related to the technique. Upon review of the detailed report of the bone scintigraphy, the protocol revealed that technetium-99m methylene diphosphonate (Tc-99m MDP) tracer was used instead of Tc-99m pyrophosphate (PYP). A Tc-99m PYP was done showing diffuse tracer uptake in the myocardium (Panel B, grade III uptake over the heart region with heart to contralateral ratio of 2.9 and diffuse myocardial uptake on SPECT/CT). Genetic testing revealed a p. P44S pathogenic variant in the transthyretin gene. Continued education is required for the diagnostic imaging approach in transthyretin amyloid cardiomyopathy (ATTR-CM) including which bone tracers are appropriate. Uncommon false negatives do occur in hereditary ATTR-CM, however, given the exceptionally high diagnostic accuracy of Tc-99m PYP in ATTR-CM, careful review of protocols and images are warranted when multi-modality imaging findings are discordant.
Conflict of interest: The authors have submitted their declaration which can be found in the article Supplementary material online.
Supplementary material is available at European Heart Journal online.
