Efficacy of Computed Tomography-Based Evaluation of Myocardial Extracellular Volume Combined With Red Flags for Early Screening of Concealed Cardiac Amyloidosis in Patients With Atrial Fibrillation

Abstract

Background: The prevalence of transthyretin amyloid cardiomyopathy (ATTR-CM) in atrial fibrillation (AF) patients remains unclear. We explored the efficacy of computed tomography-based myocardial extracellular volume (CT-ECV) combined with red flags for the early screening of concealed ATTR-CM in AF patients undergoing catheter ablation.

Methods and results: Patients referred for AF ablation at Oita University Hospital were prescreened using the red-flag signs defined by echocardiographic or electrocardiographic findings, medical history, symptoms, and blood biochemical findings. Myocardial CT-ECV was quantified in red flag-positive patients using routine pre-AF ablation planning cardiac CT with the addition of delayed-phase cardiac CT scans. Patients with high (>35%) ECV were evaluated using technetium pyrophosphate (^{99 m}Tc-PYP) scintigraphy. A cardiac biopsy was performed during the planned AF ablation procedure if ^{99 m}Tc-PYP scintigraphy was positive. Between June 2022 and June 2023, 342 patients were referred for AF ablation. Sixty-seven (19.6%) patients had at least one of the red-flag signs. Myocardial CT-ECV was evaluated in 57 patients because of contraindications to contrast media, revealing that 16 patients had high CT-ECV. Of these, 6 patients showed a positive ^{99 m}Tc-PYP study, and 6 patients were subsequently diagnosed with wild-type ATTR-CM via cardiac biopsy and genetic testing.

Conclusions: CT-ECV combined with red flags could contribute to the systematic early screening of concealed ATTR-CM in AF patients undergoing catheter ablation.

Keywords: Atrial fibrillation; Computed tomography-based myocardial extracellular volume; Red flags; Transthyretin amyloid cardiomyopathy.