Abstract 15125: Calculated Plasma Volume Status Predicts Survival in Aortic Valve Replacement
Background: Plasma volume (PV) expansion underlies systemic congestion in patients (pts) awaiting aortic valve replacement (AVR) and can be significant despite clinical euvolemia. Although PV status is best quantified using radioisotope assays, it can also be estimated using validated haemodialysis-based equations. We tested the prognostic utility of one such formula in pts undergoing AVR.
Methods: We analysed the relation of pre-operative PV status to outcomes in 1160 AVR pts (mean [±SD] age 68±13 yrs, EuroSCORE 6.0±3.0). PV status was calculated (Hakim RM et al) by subtracting the pts actual PV ([1-hematocrit] x [a + (b x weight)]; a and b are gender-specific constants) from their ideal PV [c x weight]; c is a gender-specific constant).
Results: Median (±IQR) PV status was -209±331 mL with 75% and 25% of pts having PV loss and excess, respectively. Patients with PV excess were more likely to be older with poorer LV ejection fractions, greater congestive symptoms, higher creatinines and EuroSCORE/Parsonnet scores and more renal, GI and neurological post-op complications, days ventilated (1.5 vs 1.2), days of high-dependency care (3.7 vs 2.6), and days hospitalised (17 vs 13) (all P<0.05). Over a median hospital stay of 8±5 days, 35 (3.0%) pts died, while over a median follow-up of 4±3 years, 85 of the 1125 (8%) discharged pts died. A higher PV status was related to greater early and late mortality (both HR 1.001, P<0.01). A PV status >-41mls optimally predicting early deaths (HR 3, CI:1-5, P=0.004, Figure A) whilst a status >-214mls optimally predicted late deaths (HR 2, CI:1-4, P=0.0003, Figure B) on ROC analyses. Both cut-offs predicted survival independently of conventional prognosticators such as age, ejection fraction, EuroSCORE, Parsonnet score and creatinine.
Conclusions: Estimating plasma volume status in AVR patients appears prognostically useful and suggests that aiming for a status around -41mLs pre-operatively might improve outcomes.
- © 2011 by American Heart Association, Inc.