Abstract 15631: The Hemodynamic Determinants and Physiologic Correlates of QTc Interval Using Impedance Cardiography in Heart Failure

Background: Prolonged QTc interval is a known risk factor for adverse cardiac events, including sudden and non-sudden cardiac death. Understanding the determinants and physiologic correlates of QTc can guide the proper strategy for the primary prevention of sudden death in high risk patients. Methods & Results: This was an observational study that recruited ambulatory heart failure patients (NYHA I-III) from an outpatient clinic in NL, Canada. In supine resting position, consented participants underwent non-invasive 12-lead ECG and hemodynamic monitoring using BioZ Dx Impedance Cardiography (Sonosite Inc., WA, USA). ECGs were evaluated by a reviewer blinded to clinical data. Participants with pacing (n=12) or left bundle branch block (n=9) were excluded. Three measures of interest were automatically computed: (1) QTc interval (i.e., from QRS onset to T offset), (2) QRS duration (i.e., from QRS onset to QRS offset), and (3) JTc (i.e., QTc interval minus QRS duration). Effect sizes were computed using Pears...