Estimated population prevalence of cardiac transthyretin amyloidosis as an incidental finding on bone scintigraphy in a university hospital in Colombia

Abstract

Abstract Background Cardiac uptake in bone scintigraphy is highly sensitive and specific for transthyretin cardiac amyloidosis (ATTR), allowing a useful noninvasive diagnostic pathway even before echocardiographic or electrocardiographic abnormalities are present. Early diagnosis translates into early treatment and, thus, improves morbidity and mortality. In Colombia, ATTR diagnosis is still delayed or missed, and no studies have described incidental cardiac uptake on bone scintigraphy. Regarding health resources, the economic impact derived from the treatment of CA in Latam requires rigorous patient selection. This study aims to bridge this gap and improve the local clinical context. Methods We performed a retrospective cohort study which included all patients older than 65 who underwent bone scintigraphy using 99m Technetium labeled hydroxy-methylene- diphosphonate (HMDP) between January 2020 to December 2022 at our institution. Two independent physicians screened the bone scans, which a Nuclear Imaging specialist following the American Society of Nuclear Radiology guidelines then graded. Bone scans indicated for suspicion of ATTR were excluded. The prevalence of cardiac uptake and demographic characteristics were assessed. Results A total of 1206 patients were analyzed. Thirty-eight were excluded due to suspected CA. The study population, therefore, consisted of n=1168 patients with musculoskeletal (58%) and oncologic (40%) indications for scintigraphy. 55% of the sample were men; the median age was 75. Cardiac uptake was found in 1.5% of patients, from which 28% had Grade Perugini 1, 17% had Grade Perugini 2, and 56% had Grade Perugini 3. Among patients with incidental uptake, 78% were men, with a median age of 84 years; 17% had heart failure, 11% had aortic stenosis, 11% had dysautonomia, 6% had polyneuropathy, 22% had spinal stenosis, and 17% had carpal tunnel syndrome. Conclusion We describe the first South American cohort of incidental cardiac uptake in HMDP scintigraphy. The observed incidence in this cohort was 1.5%, in concordance with previously published data in other continents. Bone scintigraphy is highly available in all regions of Colombia, allowing the identification of subclinical ATTR before severe functional impairment occurs and prompt treatment initiation in CA patients. The development of reference centers for the healthcare of CA patients allows the incorporation of clinical pathways that facilitate the approach of patients with incidental myocardial uptake in bone scans requested for non-cardiac causes, which warrant further clinical assessment and follow-up.Clinical characteristicsIncidental cardiac uptake