Association of Peripheral Nerve Block with Postoperative Myocardial Injury in High-risk Cardiac Older Adults Undergoing Hip Fracture Surgery: A Two-center Retrospective Cohort Study

BACKGROUND: Myocardial injury after hip fracture surgery is common and associated with increased mortality. Acute pain is an important risk factor, but whether peripheral nerve block (PNB) could reduce postoperative myocardial injury remains unclear. This study aimed to evaluate the association between single-injection PNB, administered as an adjunct to general or neuraxial anesthesia, and postoperative myocardial injury in high-risk cardiac older adults undergoing hip fracture surgery. METHODS: In this retrospective cohort study, patients 65 yr or older who underwent hip fracture surgery during general or neuraxial anesthesia between 2012 and 2023 were included. Based on medical records, patients who received a single-injection PNB as an adjunct were assigned to the PNB group; those who did not were assigned to the non-PNB group. The primary outcome was postoperative myocardial injury, defined as any postoperative cardiac troponin measurement exceeding the 99th percentile upper reference limit during the index hospitalization. Confounding effects were adjusted using inverse probability of treatment weighting based on 27 baseline and intraoperative variables. A weighted logistic regression model was used to estimate odds ratio for PNB versus non-PNB groups. Missing data (24.3% of cases) were imputed using multiple imputation. RESULTS: Data from 1,467 patients were included in the final analysis. Postoperative myocardial injury occurred in 12.0% (96 of 798) of patients in the PNB group and 21.5% (144 of 669) in the non-PNB group. The weighted logistic regression analysis showed that single-injection PNB was associated with a significantly lower odds of postoperative myocardial injury (adjusted odds ratio, 0.60; 95% CI, 0.44 to 0.82; P = 0.002). CONCLUSIONS: Single-injection PNB as an adjunct to general or neuraxial anesthesia was associated with a reduced risk of postoperative myocardial injury in high-risk cardiac older adults undergoing hip fracture surgery, possibly through mitigating the link between pain and myocardial injury. Further prospective trials are needed to validate these findings.