Association of Prior Implantation of HeartMate II Left Ventricular Assistive Device with Post-Heart Transplant Mortality

Abstract

Purpose The impact of continuous-flow left ventricular assistive devices (LVAD) on post-heart transplant survival has not being well explored. This study investigates post-heart transplant mortality associated with prior implantation with the HeartMate II (HMII) LVAD in cohort of heart transplant recipients in the United Network for Organ Sharing (UNOS) database. Methods and Materials The study population includes patients (n=43,968) listed after April 2004 in the UNOS database– the era of continuous-flow LVADs. Of the 6,150 patients on LVADs, we further limited our sample to include only patients implanted with HMII LVAD prior to heart-transplantation (n=1,389) and those without any LVAD (n=19,693). Preliminary descriptive statistics suggested extensive heterogeneity in patient characteristics between HMII assisted patients and non-LVAD assisted patients. Subsequently, propensity scores were used to match HMII assisted patients and non-LVAD patients using these covariates – recipient characteristics (age, gender, race, UNO list status, duration on wait list, diabetes, BMI, education, kidney function, chronic comorbidities, ICD implantation, infection, acute graft rejection, inotropes use, and ischemic time), and donor characteristics (age, gender, race, and BMI). This resulted in a final control sample of 5,902, with a median age of 54 years (range, 18 – 77 years). Time from heart transplant to death was evaluated using both stratified and time-dependent CPH (spell out CPH) models. Results HMII was associated with higher risk of 30-day (HR=1.58, 95%CI: 0.83 – 2.72, p=0.18) and one-year mortality (HR=1.80, 95%CI: 1.10 – 2.94, p=0.02) with statistical significance observed for only one-year mortality. The use of HMII however was observed to be associated with lower risk of mortality after a year of post-heart transplant surgery, HR=0.62, 95%CI: 0.53 – 0.72, p Conclusions HeartMate II may improve post-heart transplantation survival among patients that survive past their first year of heart transplantation.