Negative methylene diphosphonate scintigraphy in biopsy-confirmed hereditary transthyretin Ala117Ser cardiac amyloidosis: a case report

Abstract

99mTc-pyrophosphate (99mTc-PYP) scintigraphy is highly sensitive and specific for the diagnosis of transthyretin cardiac amyloidosis (ATTR-CA). Commonly used alternative tracers included 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid (99mTc-DPD) and 99mTc-hydroxymethylene diphosphonate (99mTc-HMDP). A 61-year-old Chinese man presented with signs indicative of left ventricular hypertrophy. Genetic testing revealed heterozygous transthyretin Ala117Ser mutation. Scintigraphy using 99mTc-methylene diphosphonate failed to show myocardial uptake. Five months later, the patient underwent permanent pacemaker implantation. Tafamidis was used irregularly, and the patient died 2 years later. 99mTc-methylene diphosphonate may not be appropriate for diagnostic use in ATTR-CA patient with transthyretin Ala117Ser mutation.