Serial extracellular volume quantification using cardiac magnetic resonance imaging in transthyretin amyloidosis patients treated with tafamidis

OBJECTIVES: Cardiac transthyretin amyloidosis (ATTR CA) has been increasingly recognized as an important heart failure (HF) entity, and cardiac magnetic resonance (CMR) imaging is a mainstay in the clinical evaluation of this disease. However, studies evaluating the prognostic values of longitudinal data in ATTR CA patients with disease-modifying therapies are lacking. We aimed to assess the prognostic significance of serial quantification of extracellular volume (ECV) in ATTR CA patients treated with tafamidis. MATERIALS AND METHODS: The present study included ATTR CA patients who received ≥ 3 months of tafamidis treatment and underwent baseline and CMR, including ECV quantification. The primary endpoint was a composite of all-cause mortality, cardiac transplantation, or hospitalization due to HF. RESULTS: Between June 2016 and June 2020, 54 patients were included in the present analysis and were representative of a typical ATTR CA cohort (median age: 76.7 years, male participants: 79.6%). The median time on tafamidis before follow-up CMR was 6.0 months (interquartile range (IQR): 6.0-8.3). Participants depicted typical structural changes for ATTR CA patients with markedly elevated ECV (51.4% (IQR: 41.3-57.6), normal range: 20-32%) and myocardial ventricular hypertrophy (intraventricular septum: 19 mm (16.0-22.0), normal range: 5-12 mm). Change of ECV was the only parameter among clinical, laboratory, and CMR parameters that was independently associated with the composite endpoint (HR: 1.077, 95% CI: 1.013-1.145, p = 0.017). CONCLUSIONS: Change of ECV was the only predictor of adverse outcome among clinical, laboratory, and imaging parameters in our cohort of tafamidis-treated ATTR CA patients. KEY POINTS: Question What is the prognostic significance of serial ECV quantification in transthyretin amyloidosis patients on tafamidis treatment? Findings Change of ECV is a strong predictor of a combined endpoint consisting of all-cause mortality, cardiac transplantation, or hospitalization due to HF. Clinical relevance Patients with increasing ECV might potentially benefit from a change in amyloid-specific treatment to a different agent.