Extract

A 60-year-old woman presented for an atrial fibrillation (AF) ablation. Her pre-ablation workup included an electrocardiogram (EKG) and transthoracic echocardiogram (TTE). The EKG (PanelA) was notable for AF, right bundle branch block, and low voltage. TTE (PanelB) revealed increased left ventricular wall thickness with restrictive physiology. Cardiac magnetic resonance imaging (cMRI) (PanelC) was obtained to evaluate for infiltrative cardiomyopathy; however, it only demonstrated a small scar (red arrowhead) involving the basal septum. After this initial workup, the patient underwent AF ablation. Intracardiac echocardiography demonstrated marked thickening of the interatrial septum (PanelD; arrow). To help characterize the underlying myocardial substrate, a detailed three-dimensional electroanatomic voltage map, using the CARTO Mapping System (Bipolar voltage cut-offs 0.1–0.4 mV), was obtained. The map demonstrated diffuse low voltage of the left atrium in the left and right anterior oblique (PanelsE and F) projections, compatible with extensive scarring. This finding coupled with the clinical presentation was highly suggestive of an infiltrative cardiac process. Despite the non-diagnostic cMRI, the findings on electroanatomic mapping prompted an endomyocardial biopsy, which revealed AL-type cardiac amyloidosis.

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