Abstract 16697: 99mTc-DPD Scintigraphy in Transthyretin-Related Cardiac Amyloidosis: Diagnostic and Prognostic Implications
Purpose: Few scintigraphic tracers are informative on myocardial amyloid infiltration. We aimed to assess: the accuracy of 99mTc-DPD scintigraphy in differential diagnosis between primary (AL) and transthyretin-related (TTR) (both mutant and wild-type) echocardiographically diagnosed amyloidotic cardiomyopathy (AC); the role of 99mTc-DPD in detecting cardiac amyloidosis across a wide spectrum of myocardial involvement in TTR amyloidosis; the prognostic role of 99mTc-DPD in TTR etiology.
Methods: We evaluated: 39 patients with AL-AC; 55 patients with TTR-AC (37 mutant; 19 wild-type); 21 hereditary TTR (ATTR) patients or asymptomatic TTR mutations carriers (6 Val30Met, 15 non-Val30Met) without any echocardiographic abnormalities. Myocardial uptake of 99mTc-DPD (740 MBq iv) was semiquantitatively/visually assessed at 3 h (and 5 min).
Results:. Semiquantitative measures of late (3 h) 99mTc-DPD uptake were ∼2–3 fold higher in TTR-AC (table). A visual score = 2 was accurate in identifying TTR etiology (accuracy 94%, positive predictive value 90%; negative predictive value 100%). Among ATTR carriers, 4 subjects with non-Val30Met mutations (Ala36Pro, Gly47Ala, Thr49Ala, Glu89Gln) showed high H/WB values: in all these cases endomyocardial biopsies showed a mild/moderate amyloidotic infiltration. Univariate predictors of survival free from major cardiovascular events (MACE) were: age, NYHA class, LV-ejection fraction, restrictive filling pattern and H/WB (p ≤0.01). At COX model based on instrumental variables, H/WB predicted MACE (HR 1.146, 95%CI 1.010–1.300, p=0.035).
Conclusions: 99mTc-DPD scintigraphy can provide an accurate differential diagnosis between AL and TTR-related AC. 99mTc-DPD can identify early myocardial involvement, even before the appearance of echocardiographic abnormalities, at least in cases with non-Val30Met TTR mutations. Myocardial 99mTc-DPD uptake is an independent predictor of MACE free survival in TTR etiology.
- © 2010 by American Heart Association, Inc.