Understanding Longitudinal Changes in Pulmonary Vascular Resistance After Left Ventricular Assist Device Implantation

Elevated pulmonary vascular resistance (PVR) is common in patients with advanced heart failure. PVR generally improves after left ventricular assist device (LVAD) implantation, but the rate of decrease has not been quantified and the patient characteristics most strongly associated with this improvement are unknown. We analyzed 1581 patients from the Interagency Registry for Mechanically Assisted Circulatory Support registry who received a primary continuous-flow LVAD, had a baseline PVR of ≥3 Wood units (WU), and had PVR measured at least once postoperatively. Multivariable linear mixed effects modeling was used to evaluate independent associations between postoperative PVR and patient characteristics. PVR decreased by 1.53 WU (95% confidence interval [CI] 1.27–1.79 WU) per month in the first 3 months postoperatively, and by 0.066 WU (95% CI 0.060–0.070 WU) per month thereafter. Severe mitral regurgitation at any time during follow-up was associated with a 1.29 WU (95% CI 1.05–1.52 WU) higher PVR relative to absence of mitral regurgitation at that time. In a cross-sectional analysis, 15%–25% of patients had persistently elevated PVR of ≥3 WU at any given time within 36 months after LVAD implantation. The PVR tends to decrease rapidly early after implantation, and only more gradually thereafter. Residual mitral regurgitation may be an important contributor to elevated postoperative PVR. Future research is needed to understand the implications of elevated PVR after LVAD implantation and the optimal strategies for prevention and treatment.