We determined the left ventricular mass index (LVMI) cut-off value for the risk of major adverse cardiac and cerebrovascular events (MACCE) in patients undergoing aortic valve replacement (AVR) for aortic regurgitation (AR) and investigated the effect of preoperative left ventricular remodeling on long-term outcomes postoperatively. Of the 1,580 patients who underwent surgical AVR at Shiga University of Medical Science between January 2002 and December 2022, we retrospectively analyzed data for 263 patients who underwent surgery for AR. The receiver operating characteristic curve showed that the cut-off value of preoperative LVMI for the incidence of MACCE was 200 g/m2(area under the curve=0.692). We compared postoperative outcomes between patients with preoperative LVMI >200 g/m2(n=92) and those with preoperative LVMI ≤200 g/m2(n=171) after adjusting for preoperative characteristics using inverse probability of treatment weighting. The mean (±SD) follow-up period was 6.9±5.1 years. The rate of MACCE at 10 years was significantly higher in patients with preoperative LVMI >200 g/m2than in those with preoperative LVMI ≤200 g/m2(25.6% vs. 13.5%; P=0.020). In multivariable Cox models, preoperative LVMI >200 g/m2was significantly associated with a higher risk of MACCE (hazard ratio 2.356, P=0.006). Preoperative LVMI >200 g/m2was associated with a higher rate of MACCE in patients undergoing AVR for AR.