P51: Implications of Significant (>10%) Changes in Body Mass Index in a Contemporary HeartMate 3 Cohort

Background: Current assumptions regarding the trends in body mass index (BMI), and their associated outcomes, after implantation of left ventricular assist devices (LVADs) are based almost exclusively on experiences with old pumps that have already been withdrawn from the market. In this study, we aimed to address the void of evidence on potential associations between significant BMI changes and outcomes after HeartMate 3 (HM3) implantation. Methods: This is a cohort study of patients who received a HM3 between May 2015 and July 2020 at a large academic LVAD program. Subjects were followed for at least 1 year after implantation. Their BMIs were recorded during euvolemia at baseline (prior to HM3), 1, 3, 6, 9, and 12 months. Patients who experienced significant (>10%) BMI gain (BMI-Gain) or loss (BMI-Loss) at 12 months were stratified accordingly and their baseline characteristics and outcomes compared. Results: Among the 168 patients who received a HM3 during the study period, 58 (34.5%) experienced significant BMI-Gain, whereas 16 (10.1%) had significant BMI-Loss at 12 months. Their baseline characteristics, including age, sex, comorbidities, and blood tests, were very similar except for their baseline albumin (BMI-Gain: 3.2 [±0.5] g/dL vs BMI-Loss: 3.5 [±0.5] g/dL; p=.026), and preoperative BMI, which was significantly lower in the BMI-Gain group (26.7 [±4.7] kg/m2 vs 29.7 [26.3-35.3] kg/m2; p=.019). Overall, patients who experienced BMI-Gain tended to be more in the lower BMI classifications than their BMI-Loss counterparts (p=.029). The latter group also had more patients with BMI < 35 kg/m2 (11 [68.8%] vs 56 [96.6%); p=.001). Notably, all patients in the BMI-Loss group reached a BMI <35 kg/m2, which was only seen in 43 (74.1%) of the BMI-Gain patients; p <.031 (Figure 1). Patients who experienced BMI-Loss also had longer length of stay in the intensive care unit after index surgery (11.5 [9-15.5] vs 7 [6-12]; p=.0097), and (non-statistically significantly) higher rates of the composite of percutaneous gastric tube or tracheostomy (3 [18.8%] vs 2 (3.5%); p=.064), and mortality beyond 1 year (3 [18.8%] vs 2 (3.5%); p=.064). All other outcomes, including rates of heart transplantation, reintubations, discharge destination, long-term dialysis, stroke/TIA, bleeding requiring hospitalization/procedures, gastrointestinal bleeding, and heart failure readmissions showed no statistically significant differences. Conclusions: Patients who experienced significant (>10%) loss of their BMI after receiving a HM3 tended to have higher BMI at baseline. They experienced a longer stay in the intensive care unit and displayed non-statistically significant trends towards higher rates of complications, especially mortality beyond 1 year and the composite of percutaneous gastric tube or tracheostomy. This study was likely underpowered and analyses with larger samples are warranted to draw more definitive conclusions on this topic.