Utility of 99 mTc-Pyrophosphate Scintigraphy in Diagnosing Transthyretin Cardiac Amyloidosis in Real-World Practice

Amyloid transthyretin (ATTR) cardiac amyloidosis has now been recognized as one of the major causes of heart failure, especially in elderly patients. The

99 mTc-PYP scintigraphy was useful, with high sensitivity and specificity in the screening diagnosis for ATTR cardiac amyloidosis, which is difficult to diagnose on clinical characteristics alone. 99 mTc-PYP scintigraphy should be considered to elucidate the underlying causes of heart failure, especially in elderly patients based on the higher prevalence of ATTR cardiac amyloidosis in this population.

Ninety-eight patients underwent 99 mTc-PYP scintigraphy in the previous 3 years (PYP positive/negative, 18/80), of whom 29 underwent concomitant endomyocardial biopsy (ATTR positive/negative, 9/20). The sensitivity and specificity of 99 mTc-PYP scintigraphy for the diagnosis of biopsy-proven ATTR amyloidosis were 0.889 and 0.950, respectively. Age, gender, N-terminal prohormone of brain natriuretic peptide (NT-proBNP) level, or electrocardiogram findings did not differ significantly between PYP-positive and PYP-negative patients. Left ventricular (LV) wall thickness was significantly greater in PYP-positive than in PYP-negative patients, but LV ejection fraction or prevalence of atrial fibrillation was similar between groups. In the PYP-positive patients, higher uptake of PYP correlated with younger age and lower NT-proBNP. Conclusions: 99 mTc-PYP scintigraphy was useful, with high sensitivity and specificity in the screening diagnosis for ATTR cardiac amyloidosis, which is difficult to diagnose on clinical characteristics alone. 99 mTc-PYP scintigraphy should be considered to elucidate the underlying causes of heart failure, especially in elderly patients based on the higher prevalence of ATTR cardiac amyloidosis in this population.