Abstract 12254: Predictors of Transthoracic Impedance in Patients Undergoing Electrical Cardioversion

Abstract

Introduction: Successful synchronized direct current cardioversion (DCCV) requires adequate current delivery to the heart. However, adequate current for successful DCCV is not yet established. Trans-myocardial current depends on two factors: input energy and transthoracic impedance (TTI). While factors affecting TTI have been studied in animal models, factors affecting TTI in humans have not been well established. Here we explored potential factors that affect TTI in humans. Methods: Retrospective review of consecutive patients undergoing DCCV at a large quaternary medical center between October 2019 and December 2020 was conducted. Pertinent clinical information, including demographics, echocardiography findings, laboratory findings and body characteristics were collected. Cardioversion details including joules delivered and TTI were recorded by the defibrillator for each patient’s first shock. Predictors of thoracic impedance were assessed using multivariable regression analysis after adjustment for confounders. Results: A total of 180 patients were analyzed, 31% of which were female. Mean impedance was 73.15 ± 21.50 (range 39-208). In multivariate analysis, higher TTI was significantly associated with higher BMI (p<0.001, Figure ) and female gender (p=0.006) after adjustment for all confounders. Other factors including age, history of cardiac surgery, left ventricular ejection fraction, left atrial size, brain natriuretic peptide, and antero-posterior chest diameter were not associated with TTI. Conclusion: Our results align with prior studies that body habitus and gender affect TTI and suggest that adjustments in input energy based on these factors may be required for appropriate trans-myocardial current delivery in synchronized cardioversion.