Abstract Body (Do not enter title and authors here): Introduction:
Language barriers represent an often-overlooked determinant of health equity. This study evaluates the impact of limited English proficiency (LEP) on major adverse cardiac events (MACE) and mortality in patients undergoing cardiovascular surgery. We hypothesized that patients with LEP have a higher incidence of adverse outcomes compared to English proficient patients.

Methods:
We conducted a retrospective cohort study using Cosmos, a longitudinal national electronic health record dataset. Patients were classified as having LEP if their record indicated a preferred language other than English. Adult patients aged 18-95 years who underwent coronary artery bypass grafting, valvular surgery, or thoracic aorta surgery in the United States (January 2016 - February 2025) were included. Exclusion criteria were missing language data, first in-person encounter <1 year prior to surgery, history of metastatic cancer or dialysis, and nursing home residence within 90 days of surgery. The primary outcome was MACE, a composite of stroke, revascularization, and hospitalization for myocardial infarction or heart failure. The secondary outcome was all-cause mortality. The cumulative incidence of MACE was estimated via a competing risk framework, while the cumulative incidence of mortality was estimated with the Kaplan-Meier method. Multivariate Cox proportional hazard regressions were fitted for all outcomes.

Results:
The cohort included 12,706 LEP patients (28.8% female) and 393,612 English-proficient patients (33.2% female). Differences in baseline characteristics included age, race, and comorbidity burden. The unadjusted cumulative incidence of MACE was higher in LEP patients, but all-cause mortality was lower (Figure 1). Over the follow-up period, the incidence rate of MACE for English proficient patients vs LEP was 185 vs 219 per 1000 patient years and 39 vs 36 per 1000 patient years for mortality. The adjusted hazard ratio for MACE was 0.97 (95% CI: 0.94 - 1.01, p = 0.19) and 0.89 (95% CI: 0.83 - 0.95, p <0.001) for mortality.

Conclusions:
LEP was associated with higher unadjusted cumulative incidence of MACE and lower mortality, but only the association with mortality persisted after regression analysis. Our findings highlight the need for further research into the impact of language proficiency on outcomes after cardiac surgery and the potential benefit of targeted interventions to address language-related disparities.