Effects of tafamidis on serial [99mTc]Tc-DPD scintigraphy in transthyretin amyloid cardiomyopathy

Purpose

The relevance of repetitive [^99mTc]Tc-DPD scintigraphy in wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM) remains unclear. We investigated the impact of tafamidis on cardiac [^99mTc]Tc-DPD uptake, clinical, and laboratory markers at 6 and 12 months, and correlated 12 months [^99mTc]Tc-DPD uptake regression with survival.

Methods

This single-center study enrolled 39 ATTRwt-CM patients. Upon treatment initiation with tafamidis, patients underwent follow-up [^99mTc]Tc-DPD scintigraphy, and clinical and laboratory evaluations at 6 months (n = 6) and 12 months (n = 13), or both (n = 20).

Results

Tafamidis resulted in a significant decline in Perugini score (6 months p = 0.008, 12 months p < 0.001), and (semi-)quantitative [^99mTc]Tc-DPD uptake (total cardiac uptake: baseline 816 [522–933] cps, vs. 6 months 634 [502–734] cps, p = 0.003, vs. 12 months 523 [108–754] cps, p = 0.001). Clinical and laboratory improvements were observed (NYHA: 6 months p = 0.007, 12 months p = 0.033; NT-proBNP: baseline 2586 [1271–5561] ng/L, vs. 6 months 2526 [1109–4786] ng/L, p = 0.016, vs. 12 months 2340 [1411–4749] ng/L, p = 0.012). In Kaplan–Meier analysis, a decrease in right ventricular [^99mTc]Tc-DPD tracer uptake equal to or greater than the median value at 12 months (-30%) was associated with improved survival (log-rank p = 0.021).

Conclusions

Tafamidis in ATTRwt-CM resulted in significant reductions of cardiac [^99mTc]Tc-DPD uptake, NYHA class, and cardiac biomarkers at 6 and 12 months. Regression of right ventricular [^99mTc]Tc-DPD uptake at 12 months was associated with improved survival.