Predictive value of overt and non-overt volume overload in patients with high- or low-gradient aortic stenosis undergoing transcatheter aortic valve implantation

Abstract

Background: The plasma volume status (PVS) is considered a marker of non-overt cardiac congestion and is of prognostic value. Patients with low-flow, low-gradient (LFLG) aortic stenosis (AS) suffer from impaired left ventricular function and show signs of heart failure (HF). We hypothesized that PVS might predict post-interventional rehospitalization and cardiovascular mortality in high-risk patients undergoing transcatheter aortic valve implantation (TAVI).

Methods: In this retrospective, observational analysis, PVS before transfemoral TAVI was calculated by a formula taking into account hematocrit and weight. The predictive performance of PVS was compared with that of prior cardiac decompensation (PCD).

Results: In the entire cohort of n=2,458 patients, PVS >-4% (high plasma volume) identified patients (n=1,013) with a higher post-interventional 1-year mortality rate than patients (n=1,445) with a PVS ≤-4% (low plasma volume). However, PVS lost prognostic independence when adjusted for anemia, whereas PCD did not. A high PVS and PCD were not correlated, and both parameters similarly revealed a low sensitivity and specificity but a high negative predictive value (NPV) for future HF events. PVS was not different between control patients (n=1,512) and those with intermediate (paradoxical LFLG-AS, n=327) or high risk scores (LFLG-AS, n=239). The accuracy of high PVS in predicting adverse events in these subpopulations was the same as in the study population overall. Kaplan-Maier analyses demonstrated similar prognostic impacts for PVS and PCD.

Conclusions: PVS and PCD represent two independent parameters of volume overload with unfavorable prognostic significance. Pre-interventional PVS does not appear to be suitable for predicting clinical outcomes in high-risk patients undergoing TAVI.

Keywords: Transcatheter aortic valve implantation (TAVI); heart failure (HF); low-flow low-gradient aortic stenosis (LFLG-AS); plasma volume status (PVS).

Figure 1

Flow chart illustrating the creation of the study populations. TAVI, transcatheter aortic valve implantation; AVAi, aortic valve area index; AS, aortic stenosis; SVI, stroke volume index; NFLG-AS, normal-flow low-gradient aortic stenosis; PVS, plasma volume status; MPG, mean pressure gradient; LVEF, left ventricular ejection fraction; pLFLG-AS, paradoxical LFLG-AS; LFLG-AS, low-flow low-gradient AS.

Figure 2

Survival curves based on pre-interventional PVS or PCD in the entire study population. Kaplan-Meier analysis of all-cause mortality of patients with (A) PVS (plasma volume status) ≤−4% (low plasma volumes) vs. PVS >−4% (high plasma volumes); (B) PCD (prior cardiac decompensation) before TAVI vs. no PCD. PVS, plasma volume status; PCD, prior cardiac decompensation; PVS, plasma volume status; TAVI, transcatheter aortic valve implantation.

Figure 3

Survival curves based on the pre-interventional PVS or PCD in patients with LFLG-AS. Kaplan-Meier analysis of all-cause mortality of patients with (A) HG-AS, (B) LFLG-AS and (C) pLFLG-AS. Upper panels: Survival curves based on PVS ≤−4% (low plasma volumes) vs. PVS >−4% (high plasma volumes). Lower panels: survival curves based on PCD (prior cardiac decompensation) before TAVI vs. no PCD. PVS, plasma volume status; PCD, prior cardiac decompensation; LFLG-AS, low-flow low-gradient aortic stenosis; HG-AS, high-gradient aortic stenosis; pLFLG-AS, paradoxical low-flow, low-gradient aortic stenosis; TAVI, transcatheter aortic valve implantation.