Impact of High-Sensitivity Cardiac Troponin I Elevation After On- and Off-Pump Coronary Artery Bypass Grafting on Long-Term Prognosis

Background

Postoperative myocardial injury is correlated with long-term prognosis after coronary artery bypass grafting (CABG) and is diagnosed according to troponin levels, which vary substantially upon surgical strategies. We aimed to explore the troponin I cutoff values for prognostically significant myocardial injury separately in on-pump and off-pump procedures with the use of a high-sensitivity assay (hs-cTnI).

Methods

Patients who underwent isolated CABG from 2018 to 2020 with available perioperative hs-cTnI measurements were included in this study. We explored the relationships between hs-cTnI levels and different outcomes. To identify hs-cTnI threshold levels indicative of higher risks, restrictive spline regressions were performed for on-pump and off-pump procedures.

Results

A total of 7813 patients were included with a median follow-up of 2.7 years (interquartile range 1.7-3.3 years), 218 (2.8%) of whom died. Adjusting for clinical variables, the study found a significant association between peak hs-cTnI levels within the first 48 hours after surgery and all end points. The spline regressions demonstrated that the hs-cTnI levels measured within 48 hours after surgery that were associated with a hazard ratio of more than 1.00 for all-cause death were 1446 ng/L (55.6 × upper reference limit [URL], 95% confidence interval [CI] 45.0-106.5 × URL) for on-pump and 564 ng/L (21.7 × URL, 95% CI 21.0-30.2 × URL) for off-pump.

Conclusions

Elevated hs-cTnI levels after CABG were associated with poorer longer-term outcomes. A prognosis-relevant hs-cTnI cutoff value within 48 hours after CABG for on-pump is significantly higher than that for off-pump.