Left Ventricular End‐Diastolic Diameter Predicts Clinical Outcomes in Patients Supported With Surgically Implanted Microaxial Flow Pump

Background This study sought to determine the impact of left ventricular size on clinical outcomes after a microaxial flow pump was surgically implanted. Methods In this retrospective cohort study, we included patients who received a surgical microaxial left ventricular assist device from May 2020 to February 2024 at 2 high‐volume centers in the United States. Patients were categorized into 2 groups based on their preimplant left ventricular end‐diastolic diameter (LVEDD): “small LVEDD,” defined as LVEDD ≤5.5 cm, and “large LVEDD,” defined as LVEDD >5.5 cm, respectively. End points were all‐cause death at 30 days after device implantation, in‐hospital death, death 30‐days after discharge, and survival at 30‐month follow‐up. Results Two‐hundred sixty‐two patients received an Impella 5.5. Preimplant LVEDD was documented in 194 (74%) patients, where 50 patients had LVEDD ≤5.5 cm and 144 patients had LVEDD >5.5 cm. Patients with a small LVEDD had a higher rate of all‐cause death at 30 days after device implantation (32% versus 11.8%, P =0.002), in‐hospital death (42% versus 20.1%, P =0.004), and death 30 days after discharge (44% versus 20.8%, P =0.003). In adjusted analyses, patients with a greater LVEDD had 62% decreased risk of long‐term death (hazard ratio, 0.39 [95% CI, 0.19–0.76]; P =0.001), compared with patients with a smaller LVEDD. Conclusions In this real‐world, all‐comer study, we found that patients with reduced left ventricular dimension who required an Impella 5.5 had worse outcomes. Further research is warranted to recapitulate our observations across more centers.