Risk Score to Predict Right Heart Failure in LVAD Recipients
Is the novel risk score for early right-sided heart failure (RHF) after left ventricular assist device (LVAD) implantation valid?
The study authors used the European Registry for Patients With Mechanical Circulatory Support (EUROMACS) to identify adult patients undergoing continuous-flow LVAD implantation with mainstream devices. They randomly divided eligible patients (n = 2,988, age >18 years) into derivation (n = 2,000) and validation (n = 988) cohorts. The primary outcome was early (<30 days) severe postoperative RHF. They defined RHF as receiving short- or long-term right-sided circulatory support, continuous inotropic support for ≥14 days, or nitric oxide ventilation for ≥48 hours. The secondary outcome was all-cause mortality and length of stay in the intensive care unit. They entered covariates found to be associated with RHF (exploratory univariate p < 0.10) into a multivariable logistic regression model. They then generated a risk score using the relative magnitude of the exponential regression model coefficients of independent predictors at the last step after checking for collinearity, likelihood ratio test, c index, and clinical weight at each step.
The mean age of the cohort was 53 ± 13 years, and 18% (n = 523) were women. The majority were white (68%, n = 2,022). The main type of HF was nonischemic (66%, n = 1,985). The main indication for LVAD was bridge to candidacy (37%, n = 1,102), followed by bridge to transplantation (24.5%, n = 731). HeartWare HVAD was the most used LVAD brand (50.5%, n = 1,509), followed by HeartMate II (40.3%, n = 1,204), and the minority received Heart-Mate 3 (8%, n = 240). Early severe RHF occurs in one fifth of patients with LVAD in this study and 88% of patients have mild or more impairment of right ventricular (RV) systolic function. The study authors examined 82 potential preoperative predictors from which they created a 9.5-point risk score incorporating five variables (Interagency Registry for Mechanically Assisted Circulatory Support class, use of multiple inotropes, severe RV dysfunction on echocardiography, ratio of right atrial [RA]/pulmonary capillary wedge pressure [PCWP], hemoglobin). Patients in INTERMACS class 1-3 had a 27% risk of RHF versus 12% risk for those in INTERMACS class 4-7 (p < 0.001). Additionally, patients on ≥3 inotropic agents in the preoperative period had 42% risk of RHF versus 22% risk for those on ≤2 inotropic agents (p < 0.001). In terms of semi-quantitative echocardiographic assessment, patients with severe RV dysfunction on visual score had 50% risk of RHF versus 23% for those with better RV function. Furthermore, patients with an RA/PCWP ratio >0.54 had 27.1% risk of RHF versus 16.1% for those with a lower ratio (p < 0.001). Finally, patients with hemoglobin ≤10 g/dl had 35% risk of RHF versus 23% risk for those with hemoglobin >10 g/dl (p < 0.001). The mean scores in the derivation and validation cohorts were 2.7± 1.9 and 2.6 ± 2.0, respectively (p = 0.32). RHF in the derivation cohort occurred in 433 patients (21.7%) after LVAD implantation and was associated with a lower 1-year (53% vs. 71%; p < 0.001) and 2-year (45% vs. 58%; p < 0.001) survival compared with patients without RHF. RHF risk ranged from 11% (low risk score 0–2) to 43.1% (high risk score >4; p < 0.0001). Median intensive care unit stay was 7 days (interquartile range, 4–15 days) versus 24 days (interquartile range, 14–38 days) in patients without versus with RHF, respectively (p < 0.001). The use of multiple inotropes has the greatest weight in predicting post-LVAD RHF among all five predictors. The EUROMACS-RHF risk score outperformed (p < 0.0001) previously published scores and known individual echocardiographic and hemodynamic markers of RHF.
The study authors concluded that this novel EUROMACS-RHF risk score outperformed currently known risk scores and clinical predictors of early postoperative RHF.
This is an important study because this simple and elegant risk score better predicts RHF in continuous-flow LVADs. Validation of this risk score in prospective studies is the next step, and if these findings are confirmed, this risk score should better predict RHF in continuous-flow LVAD patients.
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