Real-World Efficacy of Tafamidis in Korean ATTR-CM Patients: A Retrospective Observational Strain Analysis

BACKGROUND AND OBJECTIVES: Transthyretin amyloid cardiomyopathy (ATTR-CM) is an under-recognized condition with high mortality if untreated. Tafamidis, a transthyretin stabilizer, reduces mortality and cardiovascular events in ATTR-CM, but data in Korean populations are limited. This study evaluated the impact of tafamidis on survival and disease progression in Korean ATTR-CM patients using strain analysis of the left ventricle (LV), right ventricle (RV) and left atrium (LA). METHODS: This multicenter, retrospective study included 77 patients with confirmed ATTR-CM between July 2010 and June 2024. Patients were grouped as untreated or treated with tafamidis 20 mg or 80 mg. Strain analysis was performed at baseline and follow-up. The primary outcome was a composite of all-cause mortality and worsening heart failure. RESULTS: Compared with the untreated group, the tafamidis 20 mg group had a lower risk of the composite outcome (hazard ratio [HR], 0.29; 95% confidence interval [CI], 0.12, 0.73), with similar benefit in the 80 mg group (HR, 0.23; 95% CI, 0.06, 0.83). LV global longitudinal strain showed no significant difference (p=0.904). In contrast, LA stiffness index (LASI) and RV-pulmonary circulation coupling index deteriorated markedly in the untreated group. Over a median follow-up of 17.5 months, LASI worsened by 43.2% in the untreated group, compared to 8.0% and 8.7% increases in the 20 mg and 80 mg groups. RV-pulmonary circulation coupling index decreased by 35.8% and 1.2%, but increased by 10.9%, respectively. CONCLUSIONS: Tafamidis was associated with improved survival and slower disease progression in Korean ATTR-CM. LASI and RV-pulmonary circulation coupling index may serve as sensitive markers of treatment response.