Fluid overload (FO) puts aortic stenosis (AS) patients at risk for heart failure and death. However, conventional FO assessment, including rapid weight gain, peripheral edema, or chest radiography, is inaccurate. Bioelectrical impedance spectroscopy (BIS) allows objective and reproducible FO quantification, particularly if clinically unapparent. FO as detected with BIS has recently been linked to worse clinical outcomes of AS patients undergoing transcatheter aortic valve replacement (TAVR).

It is the aim of the present randomised trial to evaluate the potential clinical benefit of pursuing an individualized decongestion treatment strategy in consecutive TAVR patients using BIS.

This study is a randomized controlled trial investigating the effect of BIS-guided decongestive treatment on clinical outcomes in overhydrated patients scheduled for and receiving TAVR.

Centers participating in this trial are: Medical University of Vienna, Kepler University Hospital Linz

Consecutive adult patients with severe degenerative AS scheduled for TAVR will be prospectively enrolled at university-affiliated tertiary centers in Austria. Eligibility and decision for TAVR will be determined by a multidisciplinary Heart Team. All patients who are willing to participate will undergo assessment of volume status using BIS prior to intervention. Overhydrated subjects, defined as a relative fluid overload ≥7% (Rel. FO = fluid overload/extracellular water × 100%) and/or absolute fluid overload ≥1L as assessed by BIS, will then be randomly assigned to undergo BIS-guided pre- and postprocedural decongestion treatment vs. decongestion treatment based on mere clinical judgement of volume status in a 1:1 fashion. In order to avoid detection bias, FO patients in the non-BIS group as well as their treating physicians shall be blinded for BIS-results. Physicians and study participants will only be informed about the targeted dry body weight, if randomized to the BIS-guided decongestion group. Decongestion will be performed using standard medication (e.g. loop diuretics) and applied orally or intravenously, as appropriate. After TAVR, patients with FO will be followed before discharge from the hospital, after 3, 6 and 12 months.

Methods:

Patients will undergo standardized evaluation of their fluid status using a portable whole-body BIS device, the Body Composition Monitor (BCM, Fresenius Medical Care, Bad Homburg, Germany). Patients will be placed in supine position before the evaluation of their fluid status. Electrodes will be attached to the nondominant hand and the ipsilateral foot. Measurements will be conducted according to the manufacturer's manual. For each patient, only one bioelectrical impedance analysis will be performed, as this method has an adequate reproducibility. Fluid overload assessed by BCM is expressed as an absolute value in liters or as a relative value in %, calculated as the ratio between fluid overload (FO) and the content of extracellular water (ECW) and multiplied by 100 (Rel. FO = FO/ECW × 100%).

Prespecified study visits:

V0 (14+-13 days prior to TAVR): BIS measurement, pitting edema quantification, demographic factors, symptom assessment, cardiovascular risk factors, ECG, laboratory analysis (e.g. NT-pro BNP, hs-TnT), frailty assessment, KCCQ questionnaire, transthoracic echocardiography; V1 (90+-7 days post TAVR): BIS measurement, pitting edema quantification, demographic factors, symptom assessment, ECG, laboratory analysis (e.g. NT-pro BNP, hs-TnT), KCCQ questionnaire, transthoracic echocardiography; TV2 (telephone visit, 180+-7 days post TAVR): demographic factors, symptom assessment; V3 (360+-7 days post TAVR, =end of treatment): BIS measurement, pitting edema quantification, demographic factors, symptom assessment, ECG, laboratory analysis (e.g. NT-pro BNP, hs-TnT), KCCQ questionnaire, transthoracic echocardiography;

Outcome:

Cardiac outcomes (see below) will be assessed at 3 months (=prespecified interim analysis), and 12 months follwing TAVR.

Inclusion Criteria:

• Written informed consent
• Age ≥18 years
• Scheduled TAVR for the treatment of severe aortic stenosis
• Fluid overlaod ≥7% and/or ≥1L by BIS prior to TAVR (necessary to undergo randomization process)

Exclusion Criteria:

• Unwillingness or inability to participate
• Pregnancy
• Chronic dialysis
• Severe electrolyte disorders

In order to avoid detection bias, FO patients in the non-BIS group as well as their treating physicians shall be blinded for BIS-results. Physicians and study participants will only be informed about the targeted dry body weight, if randomized to the BIS-guided decongestion group.