Association of impedance cardiography parameters with changes in functional and quality-of-life measures in patients with chronic heart failure.

Assessment and prognosis of chronic heart failure is often difficult due to a lack of objective and easily obtainable parameters that accurately reflect disease status. This study was conducted to determine whether impedance cardiography (ICG) parameters were associated with changes in functional and quality-of-life measures in chronic heart failure patients. Retrospective chart review identified 64 patients (73% male, aged 73+/-13 years) with paired ICG measurements followed for 180+113 days. Outcome measures were changes in New York Heart Association class, 6-minute walk distance, patient visual analog scale score, and Minnesota Living with Heart Failure Questionnaire score. Measures of ICG, heart rate and blood pressure, left ventricular ejection fraction, and B-type natriuretic peptide levels were assessed for their association with outcome measures. From baseline to final evaluation, there were significant changes (p<0.05) in New York Heart Association class (from 3.2+/-0.5 to 3.0+/-0.6), 6-minute walk distance (from 668+/-380 m to 874+/-390 m), patient visual analog scale score (from 49+/-10 to 64+/-20), Minnesota Living with Heart Failure Questionnaire score (from 54+/-22 to 39+/-22), and ICG parameters of stroke index (from 38+/-9 to 41+/-8), left ventricular ejection time (from 273+/-42 to 291+/-33), and systolic time ratio (from 0.56+/-0.2 to 0.52+/-0.2). Changes in multivariate ICG parameters were significantly correlated to changes in New York Heart Association class (R, 0.80), 6-minute walk distance (R, 0.94), patient visual analog scale score (R, 0.69), and Minnesota Living with Heart Failure Questionnaire score (R, 0.67). ICG provides objective data that reflects changes in chronic heart failure disease status and treatment effectiveness.