Objective: The study objective was to investigate the progression of uncorrected mild aortic insufficiency and its impact on survival and functional status after left ventricular assist device implantation.Methods: We retrospectively reviewed 694 consecutive patients who underwent implantation of a continuous-flow left ventricular assist device between January 2006 and March 2018. Pre-left ventricular assist device transthoracic echocardiography identified 111 patients with mild aortic insufficiency and 493 patients with trace or no aortic insufficiency. To adjust for differences in preoperative factors, propensity score matching was used, resulting in 101 matched patients in each of the mild aortic insufficiency and no aortic insufficiency groups.Results: Although both groups showed similar survival (P ¼ .58), the mild aortic insufficiency group experienced higher incidence of readmission caused by heart failure (hazard ratio, 2.62; 95% confidence interval, 1.42-4.69; P < .01). By using the mixed effect model, pre-left ventricular assist device mild aortic insufficiency was a significant risk factor for both moderate or greater aortic insufficiency and worsening New York Heart Association functional status (P < .01).