Bioimpedance Spectroscopy for the Evaluation of Heart Failure

Bioimpedance Spectroscopy for the Evaluation of Heart Failure - a Comparison With Clinical Assessment, Lung Ultrasonography, Cardiac Biomarkers and Echocardiography

Despite impressive improvements in treatment strategies, heart failure (HF) morbidity and mortality remains substantially high worldwide. Pulmonary congestion is considered the leading cause for hospital admissions and death among patients with HF. Physical examination is crucial for titrating medical treatment in these patients, but despite a good specificity it is not sensitive enough to detect early elevated cardiac filling pressures.

The N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a recognized powerful predictor for HF prognosis. Recently, cardiotrophin-1 and galectin-3 have been proposed as new relevant biomarkers for HF evaluation.

Echocardiography can be also used to noninvasively measure left ventricular filling pressures. Lung ultrasound (LUS) through interstitial B-line evaluation has been recently proposed as a bed-side, noninvasive tool to assess interstitial lung water. B-lines correlate with NT-proBNP and E/e' levels in patients with acute dyspnea, chronic HF or after a stress test. LUS can also identify clinically silent pulmonary edema, suggesting that it may complement clinical evaluation to improve hemodynamic profiling and treatment optimization.

Biompedance is a bedside method for total body fluid status assessment. It defines individual fluid status/compartments/overload on the basis of an individual's normal extracellular volume and body composition. Recent studies indicate that bioimpedance-derived fluid overload indices are independent predictors of mortality in renal failure patients.

To date, no study has evaluated bioimpedance performance for fluid assessment in HF patients. The investigators aim to cross-sectionally compare bioimpedance parameters with clinical evaluation, LUS, cardiac biomarkers, and echocardiographic characteristics, in a cohort of incident consecutive patients with HF. Two years patients' survival will be evaluated to propose the best evaluative algorithm and rank the various methods for prognostic significance.

Inclusion Criteria:

1. age ≥18 years;
2. HF diagnosis regardless of cause as defined by the Framingham criteria and satisfying the European Society of Cardiology guidelines;

Exclusion Criteria:

1. metallic joint prostheses, cardiac stent or pacemakers, decompensated cirrhosis, pregnancy and limb amputations (due to bioimpedance technique limitations);
2. no prior diagnosis of pulmonary fibrosis (due to lung ultrasonography limitations);
3. absence of congenital heart disease