Characteristics and Clinical Value of Electroanatomical Voltage Mapping in Cardiac Amyloidosis

Background: Cardiac amyloidoses (CA) are an increasingly recognized group of infiltrative cardiomyopathies associated with high risk of adverse cardiac events. We sought to characterize the characteristics and clinical value of right ventricular (RV) electroanatomical voltage mapping (EVM) in CA. Methods: fifteen consecutive patients undergoing endomyocardial biopsy (EMB) for suspected CA (median age,75[64-78]; male,67%) were enrolled in an observational, prospective study. Each patient underwent RV high-density EVM using a multipolar catheter, and EMB. The primary outcome was death or heart failure hospitalization at 1-year follow-up. We recorded electrogram features at EMB sampling sites and electroanatomical data in the overall RV, and explored their correlations with histopathological findings and primary outcomes events. Results: A final EMB-proven diagnosis of AL or ATTR CA was formulated in 6 and 9 patients, respectively. Electrogram amplitudes in the bipolar and unipolar configurations averaged 1.55±0.44mV, and 5.14±1.50mV in the overall RV, with lower values in AL CA patients. We found a significant inverse correlation between both bipolar and unipolar electrogram amplitude and amyloid burden at EMB (p=0.001 and p=0.025, respectively). At 1-year follow-up, 7 patients(47%) experienced a primary outcome event; the extension of bipolar dense scar area at RV EVM was an independent predictor of primary outcome events at multivariable analysis(OR,2.40; p=0.037) CONCLUSIONS: In CA, electrogram amplitudes are around the lower limit of normal, yet disproportionately low compared to the increased wall thickness. Out data suggest that RV electrogram amplitude may be a quantitative marker of amyloid burden, and that RV EVM may have prognostic value.