Acute postoperative pain is associated with myocardial injury after noncardiac surgery

BACKGROUND: Uncontrolled pain after noncardiac surgery activates the sympathetic nervous system, which causes tachycardia, hypertension, and increased cardiac contractility - all of which may increase myocardial oxygen demand. We therefore determined whether time-weighted average pain scores over the initial 72 postoperative hours are associated with myocardial injury after noncardiac surgery (MINS). METHODS: We conducted a retrospective cohort analysis of adults with routine postoperative troponin monitoring after noncardiac surgery under general, regional, or combined anesthesia at tertiary level centers in Cleveland from January 2012 to December 2015. Time-weighted average pain scores were calculated from all the available pain scores, typically at 4-hour intervals, until a troponin elevation was detected. MINS was defined as peak troponin T concentrations exceeding 0.03 ng/mL within 72 hours after surgery. We used a generalized linear mixed model to assess the association between pain and MINS with 3 hospitals as clusters, adjusting for potential confounders. RESULTS: Among 2892 eligible patients, 4.5% had myocardial injury within 72 hours after surgery. Higher time-weighted average pain scores were associated with increased hazard of myocardial injury. The estimated hazard ratio for a 1-unit increase in pain score was 1.12 (95% confidence interval [CI], 1.02-1.22; P =.013), adjusting for confounding variables. CONCLUSIONS: Among patients undergoing noncardiac surgery, time-weighted average pain scores within 72 hours after surgery were significantly associated with myocardial injury.