A Clinical Prediction Model for Normalization of Pulmonary Vascular Resistance After Left Ventricular Assist Device Implantation

Abstract

Background Patients with heart failure with reduced ejection fraction (HFrEF) and elevated pulmonary vascular resistance (PVR) are at risk increased for poor outcomes and may be ineligible for heart transplantation (HT). Left ventricular assist device (LVAD) therapy can lower PVR for certain patients, but it is difficult to identify these patients preoperatively. Methods Using the INTERMACS registry, we developed a clinical prediction model to predict the likelihood of PVR normalization (≤ 3 WU) or HT within 1 year of LVAD implant among patients with baseline PVR > 3 WU. Backwards stepwise selection was used to select variables from 14 candidate predictors and logistic regression was used to estimate model coefficients. Model performance was summarized using measures of discrimination (c-statistic) and calibration (Harrel's EAVG). Internal validation was performed using bootstrap resampling over 200 iterations to generate an average calibration slope, which was used to uniformly shrink all model coefficients to generate the final model. Results There were 2209 patients available for analysis. Median preoperative PVR was 4.26 WU (IQR 3.54-5.54 WU) and the median time from LVAD implant to postoperative PVR assessment was 3 months. 1596 patients (72%) experienced PVR normalization or were transplanted within 1 year. 412 (19%) patients died and 201 (9%) were alive with persistently elevated PVR at 1 year. Final model coefficients are shown in the Table. Important predictors included older age (OR 0.72 per 10 years), severe baseline mitral regurgitation (MR) (OR 2.49 vs no MR), and increased baseline pulmonary capillary wedge pressure (PCWP) (OR 1.24 per 5 mmHg increase). The model c-statistic was 0.66 and EAVG was 0.004. Conclusion Among patients with elevated PVR, preoperative patient characteristics such as severe MR and elevated PCWP are able to predict the likelihood of PVR normalization or HT within 1 year of LVAD implantation. These findings can help to inform decision making and frame patient expectations regarding anticipated improvements in pulmonary vascular disease following LVAD surgery. Future studies are needed to investigate potential management strategies to increase the likelihood of PVR normalization with LVAD support.