PO-02-213 ELECTROANATOMICAL ASPECTS OF BIOPSY-PROVEN CARDIAC AMYLOIDOSIS

Abstract

Cardiac amyloidoses (CA) are a common and increasingly recognized group of infiltrative cardiomyopathies associated with high risk of heart failure, thromboembolic events, arrhythmias, and sudden death. Endomyocardial biopsy may be required to differentiate the amyloid type (mainly, Immunoglobulin light chain [AL] versus transthyretin-related [ATTR]) in selected cases. To describe electroanatomical characteristics of amyloid cardiomyopathy, and relate them to endomyocardial biopsy findings. We included ten consecutive patients (median age, 68 [63-77]; male, 50%) in an observational, retrospective study. All of them had a clinical diagnosis of CA, but a diagnosis of CA type was uncertain based on non-invasive findings. Therefore, all patients underwent right ventricular high-density electroanatomical mapping (EAM) using a multipolar catheter (Advisor HD Grid, Abbott), and EAM-guided endomyocardial biopsy (EMB). We recorded electrogram features at EMB sampling site, and assessed their correlation with histological findings with mixed effect models. The clinical, electroanatomical, and histological features of enrolled patients according to the EMB-proven type of CA (AL, n=6; ATTR, n=4) are resumed in Table. Electrogram amplitudes in both the bipolar and the unipolar configurations were largely preserved in the overall right ventricle, and at EMB sites. There were highly significant correlations among electrogram amplitudes in both the unipolar and bipolar configurations, and the extent of amyloid and fibrous tissue substitution at EMB (all p<0.01, Figure). We observed the strongest linear associations (i.e., highest R2) between unipolar electrogram amplitude and the percentage of amyloid tissue, as well as between bipolar electrogram amplitude and the percentage of fibrous tissue. On the other hand, electrogram duration and the number of electrogram peaks were unrelated to histological findings. The unipolar voltage cutoff that best identified regions with >15% amyloid tissue infiltration according to Youden index was 9.1 mV (sensitivity, 43%; specificity, 100%; accuracy, 77%). CA is associated with preserved electrogram amplitudes at high-density electroanatomical mapping with conventional voltage cutoffs. Nevertheless, unipolar electrogram amplitude is strongly related to the extent of amyloid infiltration, and unipolar voltage<9.1 mV is 100% specific for >15% amyloid tissue deposition.