The short and long‐term characteristics and outcomes of patients with grade 1 myocardial uptake on cardiac scintigraphy

Abstract

Abstract Aims This study aimed to characterize the final diagnosis and prognosis of patients with grade 1 myocardial scintigraphy uptake, which is an unequivocal result for the diagnosis of transthyretin cardiac amyloidosis (ATTR‐CA) requiring further invasive investigation with tissue biopsy. Methods and results We retrospectively compared the clinical and imaging parameters of patients suspected for ATTR‐CA (based on clinical and echocardiographic parameters) with grade 1 vs. grades 2/3 technetium pyrophosphate uptake on cardiac scintigraphy. Prospectively, grade 1 patients underwent re‐evaluation for ATTR‐CA at long term. Of the 132 ATTR‐CA suspected patients, 89 (67%) were diagnosed as grade 1 and 43 (33%) as grades 2/3 uptake. Grade 1 vs. grades 2/3 patients were younger and female predominant with lower biomarker levels and left ventricular mass. Based on available imaging and pathology findings, only 6 out of the 89 patients with grade 1 uptake (7%) were finally diagnosed with light‐chain cardiac amyloidosis, whereas no patient was diagnosed with ATTR‐CA. At 2 [interquartile range (IQR) 0.75, 3.25] years of follow‐up, the survival of patients with grade 1 vs. grades 2/3 uptake was significantly better [hazard ratio 0.271 (95% confidence interval 0.130 to 0.563, P = 0.0005)]. Prospectively, 30 patients with grade 1 uptake were re‐evaluated at a median follow‐up of 3.2 (IQR 2.2, 3.9) years. Their New York Heart Association class, biomarker levels, and echocardiography findings remained stable. No patient (0/25) demonstrated grades 2/3 uptake at repeated long‐term scintigraphy. Conclusions Patients with suspected ATTR‐CA and a grade 1 scintigraphy uptake demonstrate a stable clinical, laboratory, imaging, and scintigraphy phenotype along with a benign survival profile at long‐term follow‐up. Larger studies should define the optimal evaluation strategy in this population.

Keywords

• Amyloidosis
• Cardiac scintigraphy
• Immunoglobulin light‐chain amyloidosis, transthyretin amyloidosis
• Cardiac amyloidosis
• Prognosis