Evaluation of patients with worsening chronic heart failure: clinical value of impedance cardiography

Abstract

INTRODUCTION

Chronic heart failure (HF) worsening sometimes can be severe and rapid. When this happens urgent assessment and treatment is required in order to stop further worsening of symptoms and signs of HF. Between the most important diagnostic studies in this case are N-terminal pro-brain natriuretic peptide (NT-pro BNP), echocardiography and 6 min walk distance (6MWD). The use of first one is limited by its price and availability. Second is inexpensive, but in order to perform it, a qualified specialist is needed. Impedance cardiography (ICG) is a non-invasive and low-preparation required examination. Finding methods that would be non-invasive, effective, and, ideally, inexpensive is of relevance for optimizing the diagnosis of worsening chronic HF.

PURPOSE

To compare and describe the relation of left ventricular ejection fraction (LVEF), NT-pro BNP, and 6MWD with impedance cardiography in worsening chronic HF patients.

METHODS

The prospective study was conducted on sample of 82 patients (male 74 % and female 26 %, the average age was 61,4 years) who were admitted for treatment at the Department of Cardiology due to worsening chronic HF between 2021 and 2022. All participants gave their informed consent. We gathered and investigated the following information about those patients: classification of HF according to New York Heart Association (NYHA), 6MWD, concentration of NT-pro BNP and LVEF. Also, evaluation of ICG derived parameters, that, in our opinion, were most suitable for the diagnosis of HF: cardiac output (CO), cardiac index (CI), thoracic fluid content (TFC),stroke volume (SV), left cardiac work (LCW), systolic time ratio (STR) and systemic vascular resistance (SVR). ICG was performed after echocardiography by Medis Medizinische Messtechnik GmbH. MS Excel 2013 and IBM SPSS Statistics version 25.0 were used for data analysis. A p < 0,05 was considered statistically significant.

RESULTS

The distribution of patiens according to NYHA HF functional classes was as follows: NYHA class II – 28 patients (34,14 %), NYHA class III – 44 patients (53,66 %), and NYHA class IV – 10 patient (12,2 %). The analysis showed a moderately strong correlation between NT-pro BNP and ICG LCW (r=-0,443, p=0,02), NT-pro BNP and ICG TFC (r=0,515, p=0,01). Other ICG parameters mentioned in this study did not significantly correlate with NT-pro BNP (p>0,05). Also, significant moderate-strong correlation was found between 6MWD and ICG SV (r=0,564, p=0,001), 6MWD and ICG CO (r=0,625, p=0,001), 6MWD and ICG LCW (r=0,683, p=0,003). Although the correlation between LVEF and ICG STR was strong (r=0,72, p=0,0028), other ICG data revealed no statistically significant correlations (p>0,05).

CONCLUSION

ICG is a useful method for assessing hemodynamic profiles in patients with worsening chronic HF. ICG parameters, such as LCW, SV, CO, TFC and STR, might be applied for the standard diagnostics of HF, although it‘s clinical value necessitate further evaluation.