High Troponin I in Patients Following Off-pump Coronary Artery Bypass Grafting

Blood troponin I (TnI) concentrations, the reasons for increases in TnI after coronary artery bypass grafting (CABG) and the effects of TnI on short- and long-term outcomes are not well understood.

Patients undergoing off-pump CABG at Anzhen Hospital between 2011 and 2022 were reviewed. Data on peak postoperative TnI and high-sensitivity (hs) TnI were collected, and patients were divided into a high TnI group (TnI ≥10 ≥g/l or hsTnI ≥10,000 pg/ml) and low TnI group. Baseline characteristics, graft flow, perioperative outcomes and long-term mortality were compared between the two groups.

In all, 19,196 patients were included in the study (median age 63 years; interquartile range [IQR] 57-68 years; 14,423 (75.1%) male). Compared with the low TnI group, patients in the high TnI group were more likely to have an intra-aortic balloon pump inserted (17.8% vs. 2.9%; p<0.001), receive extracorporeal membrane oxygenation support (3.6% vs. 0.1%; p<0.001), and undergo early revascularisation (2.81% vs. 0.12%; p<0.001); the high TnI group also had more in-hospital deaths (2.7% vs. 0.2%; p<0.001). After propensity score matching, patients in the high TnI group had fewer grafts to the left circumflex artery (LCX; 0.71 ± 0.58 versus 0.81 ± 0.57; p<0.001) and right coronary artery (RCA; 0.89±0.53 versus 0.95±0.53; p=0.011), as well as less graft flow to the LCX (median 33 [IQR 21-55] versus 41 [IQR 25-67] ml/min; p<0.001) and RCA (30 [IQR 18-50] versus 35 [IQR 22-55] ml/min; p<0.001) than patients in the low TnI group. Patients with high postoperative TnI also had reduced long-term survival (HR 2.59; 95% CI [1.76-3.82]; p<0.001).

Elevated TnI following off-pump CABG may be associated with incomplete revascularisation in the LCX and RCA. It is also associated with increased early and late mortality.