Assessment of incidental cardiac uptake in bone scintigraphy across Spain. ECCINGO study

Abstract

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Pfizer SLU Introduction Myocardial uptake on bone scintigraphy with diphosphonates has become a useful tool for the early detection of transthyretin cardiac amyloidosis (ATTR-CM), the prevalence of which remains unknown. Purpose To assess the prevalence of myocardial uptake in bone scintigraphy in patients without previous clinical suspicion of cardiac amyloidosis (CA). Methods Observational, retrospective, multicentre study in 21 hospitals across Spain, their reference population represented 24.38% of the total national population. All scans performed for non-cardiac reasons during the months of September, October and November 2019 were reviewed. Scans with positive cardiac uptake (Perugini scores 1-3) were evaluated by a central laboratory. Medical histories of the patients with positive uptake were reviewed. Results 9864 scans were reviewed. Cardiac uptake was observed in 71 patients (0.72%) over 18 years of age (85.90% male). According to the central laboratory assessment the distribution in the Perugini grading scale was, grade 1 (23.90%), grade 2 (29.60%) and grade 3 (46.50%). No relationship between sex and Perugini grade was observed. Heart/Contralateral ratio (H/CL) was available for 24 patients with a mean of 2.1 ± 1.1 (95% CI 1.7–2.6). A third of the patients (33.80%) also presented extracardiac uptake, being the most common: bone metastasis (7.04%) abdominal wall (5.60%) and lower limbs muscular mass (4.20%). A previous heart failure (HF) diagnosis was found in the 16.90% of the patients with positive uptake, being most of them 57.10% in NYHA class II. Patients ≤ 80 y.o. were diagnosed with heart failure earlier than patients > 80 y.o. (p = 0.02) and with atrial fibrillation earlier than patients > 80 y.o. (p = 0.05). Ten patients with cardiac uptake were subsequently diagnosed with ATTR amyloidosis (ATTR-Y) with a mean delay of 10.8 months (95% CI: 6.0–16.8). All ATTR-Y patients were > 70 y.o., 90.00% were male, had left ventricular hypertrophy (LVH) compared to 25.49% of patients in whom a diagnosis of ATTR (ATTR-N) was not confirmed (p = 0.00003). Patients in the ATTR-Y group presented some episode of orthostatic hypotension and involuntary weight loss in the clinical history (30.00% in both) compared to 3.77% (p = 0.025) and 5.88% (p = 0.05) of the ATTR-N group respectively. Conclusions This national study found a prevalence of 0.72% of incidental cardiac uptake in bone scintigraphies performed for non-cardiac reasons in adult patients. The results of this study bring light on the profile of the elderly patients with incidental cardiac uptake. The referral of these patients can facilitate the early diagnosis of CA with the consequent impact on the management and prognosis of patients.