High-Sensitivity Cardiac Troponin I and Mortality Following Off-Pump and On-Pump Coronary Artery Bypass Surgery: A Secondary Analysis of the Vision Cardiac Surgery Study

OBJECTIVES: We aimed to determine whether high-sensitivity cardiac troponin I (hs-cTnI) thresholds associated with increased 30-day mortality isolated coronary artery bypass grafting (CABG) differed between those undergoing off-pump (OPCAB) and on-pump (ONCAB) CABG. METHODS: We conducted a subanalysis of patients who underwent isolated CABG in the Vascular Events in Surgery Patients Cohort Evaluation (VISION) Cardiac Surgery Study. Cox regression was used to determine the hazard ratios (HRs) for mortality based on postoperative day 1 log-transformed hs-cTnI adjusted by EuroSCORE II, with OPCAB versus ONCAB as an interaction term. HRs were modelled as a function of hs-cTnI, and the lowest troponin associated with HR ≥ 1.00 was identified for each group. RESULTS: Of the original VISION cohort, 6505 patients underwent isolated CABG (OPCAB = 1141, ONCAB = 5364). Median hs-cTnI after CABG was 2446 ng/L (interquartile range [IQR] 1164-5654), and lower after OPCAB (640 ng/L [264-1689]) than ONCAB (2972 ng/L [1536-6448], P < .001). There were no differences in 30-day mortality between OPCAB and ONCAB (1.7% vs 1.4%, P = .5). Increased log-peak hs-cTnI was associated with greater mortality after CABG (adjusted HR = 1.7 [95% CI, 1.4-2.1]). The hs-cTnI threshold associated with HR ≥ 1.00 for isolated CABG was 6549 ng/L (95% CI, 3609-8381). OPCAB versus ONCAB had a significant interaction effect on the association between hs-cTnI and mortality (interaction P = .002). The hs-cTnI threshold associated with mortality after OPCAB was ≥4708 ng/L (95% CI, 581-7177), compared to ≥6806 ng/L (95% CI, 4001-13 993) after ONCAB. CONCLUSIONS: The clinically significant hs-cTnI threshold after CABG associated with an increased risk of 30-day mortality above the baseline is substantially higher than defined by current guidelines, but lower in patients undergoing OPCAB compared to ONCAB.