Single-Center Study in Lithuania to Evaluate the Role of Transthoracic Impedance Cardiography in the Diagnosis and Outcome Evaluation of 301 Patients with Chronic Heart Failure Exacerbation

BACKGROUND: Scientific data regarding transthoracic impedance cardiography (ICG) parameters and its utility in patients with heart failure (HF) remains controversial. This study from a single center in Lithuania aimed to evaluate the role of ICG in the diagnosis and outcome evaluation of patients who were admitted to the hospital due to HF exacerbation. MATERIAL/METHODS: The sample consisted of 301 consecutive patients with a previous chronic HF diagnosis (166 men, 135 women) hospitalized for HF flare-ups. ICG data were compared to other noninvasive HF diagnostic tests. Data about patient outcomes were gathered from the Lithuanian Medical Record Database. RESULTS: A weak correlation of amino-terminal pro-brain natriuretic peptide (NT-proBNP) with thoracic fluid content (TFC) and thoracic fluid content index (TFCI) was found (r=0.204, P<0.001 and r=0.207, P<0.001, respectively). There was weak to moderate correlation of 6-min walk distance with main ICG data. There was weak correlation between left ventricular ejection fraction (LVEF) with TFCI (r=−0.163, P=0.005), systolic index (r=−0.137, P=0.017), and systolic time ratio (r=0.236, P<0.001). By multivariate Cox proportional analysis, the following parameters were independently associated with cardiac death (P<0.001): NT-proBNP ≥425.5 pmoL/L (hazard ratio (HR), 5.104, 95% confidence interval (CI) 3.326–7.832), TFC ≥36.9 1/kOhm (HR, 4.604, 95% CI 2.701–7.849), LVEF ≤40% (HR, 4.942, 95% CI 2.8256–8.647). CONCLUSIONS: The combination of non-invasively measured TFC, LVEF, and NT-proBNP showed great prognostic value for predicting readmissions and cardiac death in patients with HF.