Evaluation of Extracellular Volume Changes via Cardiac MRI in Tafamidis-Treated ATTR Amyloidosis

Overview

This study assessed extracellular volume (ECV) changes using cardiac magnetic resonance (CMR) T1-mapping in transthyretin amyloidosis (ATTR) patients treated with tafamidis. Tafamidis treatment was associated with stabilization or reduction of ECV, suggesting a beneficial effect on amyloid burden and potentially improved clinical outcomes.

Background

Cardiac transthyretin amyloidosis (ATTR CA) is a progressive cause of heart failure characterized by amyloid deposition in the myocardial extracellular space, leading to increased extracellular volume (ECV). Histological assessment via endomyocardial biopsy is the gold standard for amyloid quantification but is limited by procedural risks and sampling variability. Cardiac magnetic resonance (CMR) T1-mapping provides a validated, non-invasive method to quantify ECV and monitor disease progression. Tafamidis, a transthyretin stabilizer, has shown promise in slowing ATTR CA progression, but the prognostic relevance of serial ECV quantification during tafamidis treatment requires further investigation.

Data Highlights

Key Findings

• Tafamidis treatment stabilizes or reduces myocardial ECV in ATTR CA patients, indicating decreased amyloid burden.
• Untreated patients show a significant increase in ECV over time, reflecting disease progression.
• Reduction in nuclear imaging SUV retention index correlates with tafamidis therapy, supporting imaging findings.
• Serial CMR T1-mapping is a feasible, non-invasive tool for monitoring amyloid burden changes during tafamidis treatment.
• Patients with decreasing ECV after tafamidis treatment may have better clinical outcomes, including lower mortality and hospitalization rates.

Clinical Implications

Serial ECV quantification by CMR T1-mapping can serve as a valuable biomarker to monitor treatment response in ATTR CA patients receiving tafamidis. Identifying patients with decreasing amyloid burden may help tailor therapy and optimize clinical management. This approach supports non-invasive, longitudinal assessment of disease progression and therapeutic efficacy, potentially guiding cost-effective use of tafamidis.

Conclusion

Tafamidis treatment in ATTR CA patients is associated with stabilization or reduction of myocardial extracellular volume as measured by CMR T1-mapping, reflecting decreased amyloid deposition. Serial ECV assessment may provide prognostic information and aid in identifying patients who derive the greatest clinical benefit from tafamidis therapy.

References

1. Rettl et al. -- Effects of Tafamidis on ATTR CA Progression
2. Perugini et al. -- Bone Scintigraphy for ATTR CA Diagnosis
3. Medical University of Vienna CA Registry -- Study Protocol and Ethics