Impact of Revised Cardiac Risk Index, Individual Risk Factors, and Their Duration on Major Adverse Cardiac Events After Primary Total Knee Arthroplasty: A Nationwide Propensity-Matched Cohort Study

BACKGROUND Although the Revised Cardiac Risk Index (RCRI) is widely used to assess major adverse cardiac events (MACE) preoperatively, the impact of risk-factor duration and age stratification on its predictive performance after total knee arthroplasty (TKA) remains unclear. This study evaluated post-TKA MACE incidence and risk according to RCRI score, individual risk factors, their preoperative duration, and age strata. METHODS This retrospective cohort study used a nationwide claims database, including primary TKA patients (2017 to 2021). The RCRI was modified for claims data by defining renal impairment as chronic kidney disease stage ≥ 3. Following propensity-score matching by RCRI scores (0, 1, ≥ 2), risk factors were categorized by preoperative duration: absent, ≤ one year, or greater than one year. The primary outcomes were 30-day, 90-day, and 1-year MACE. Adjusted hazard ratios (aHRs) were estimated using stratified Cox models. RESULTS Among 72,672 matched patients, MACE incidence was 0.18, 0.40, and 1.43% at 30 days, 90 days, and one year, respectively. The MACE risk increased with the RCRI category; versus RCRI 0, RCRI 1 raised the postoperative 1-year risk (aHR 1.34, P < 0.001), whereas RCRI ≥ 2 roughly doubled the risk across all periods (aHR 1.86 to 2.15, all P-values ≤ 0.003). Moderate-to-severe renal impairment was the most consistent predictor (all P-values ≤ 0.001), especially when diagnosed ≤ one year preoperatively. Among RCRI ≥ 2 patients, age ≥ 75 years increased 30-day MACE risk (aHR 2.27, P = 0.004), whereas risk in those aged less than 75 years became significant at 90 days (P < 0.001). CONCLUSION The RCRI provides predictive validity for post-TKA MACE. Beyond static scores, risk-factor duration and age stratification offer incremental prognostic value. Patients who had recent moderate-to-severe renal impairment and older age (≥ 75 years) combined with RCRI ≥ 2 warrant closer perioperative monitoring.