Preoperative statin use and postoperative mortality in cardiac surgery patients: a retrospective cohort study of the MIMIC-IV database.

Background: The impact of preoperative statin use on postoperative survival in cardiac surgery (CS) patients remains controversial. While some randomized controlled trials (RCTs) have reported neutral or harmful effects, real-world evidence from large, granular databases like Medical Information Mart for Intensive Care IV (MIMIC-IV) can provide complementary insights into long-term outcomes and dose-response relationships. This study aimed to investigate the association between preoperative statin use and short- to medium-term postoperative mortality in cardiac surgery patients using a large, real-world database and to explore potential dose-response effects. Methods: This retrospective cohort study utilized the MIMIC-IV database [2008-2019]. We included adult patients (≥18 years) with an intensive care unit (ICU) stay of >24 hours undergoing their first CS. Patients were divided into preoperative statin users and non-users. The primary outcome was in-hospital mortality, while secondary outcomes were 30-, 90-, and 360-day mortality. Multivariable Cox proportional hazards models were constructed, adjusting for demographics, vital signs, laboratory results, and comorbidities (e.g., hypertension, diabetes, heart failure). Follow-up data were derived from hospital records and related death registry information. Results: A total of 17,172 CS patients were finally included in the study. Among 17,172 CS patients, 3,647 (21.2%) received preoperative statins. Statin users were older and had a higher burden of comorbidities such as hypertension and diabetes compared to non-users. In the fully adjusted model, preoperative statin use was associated with significantly lower in-hospital mortality rates [hazard ratio (HR) =0.708, 95% confidence interval (CI): 0.622-0.807, P<0.001]. Similar associations were observed for 30-day (HR =0.826, P=0.001), 90-day (HR =0.829, P<0.001), and 360-day mortality rates (HR =0.884, P=0.002). Dose-response analysis revealed a more significant reduction in mortality rates with high-dose (>40 mg) atorvastatin. Conclusions: In this large, real-world cohort, preoperative statin use was associated with reduced short- and medium-term mortality rates after CS, with a potential dose-dependent effect. However, given the conflicting evidence from RCTs, these findings should be interpreted cautiously. Perioperative management should be individualized, and further research is necessary to identify patient subgroups most likely to benefit from statin therapy.