High-Sensitivity Troponin I Helps Identify Patients Who Need Revascularization post cardiac surgery

The European Society of Cardiology issued recommendations to use a threshold of 70× URL of cardiac troponin in addition to ECG, echocardiographic and hemodynamic criteria to aid in the diagnosis of post-cardiac surgery myocardial infarction based on evidence of its association with mortality. Current troponin cut-offs suggested for the post-operative workup of patients following coronary artery bypass graft (CABG) surgery are based on studies using non-high-sensitive troponin assays or are arbitrarily chosen. Therefore, Dr Hazem Omran and his team conducted a study to identify an optimal cut-off and timing for a proprietary hs-cTnI assay to facilitate post-operative clinical decision-making.

In a retrospective study, the researchers included 4,684 patients who underwent elective isolated CABG from 2013–to 2019. They measured hs-cTnI was measured 24 hours prior to surgery as well as serially at 4-hour intervals up to 48 hours post-surgery. The major outcome assessed was repeat revascularization (percutaneous coronary angiography or redo surgery).

Key findings of the study:

• Upon analysis, the researchers found an optimal cut-off value for peak hs-cTnI of >13 000 ng/L [>500× the upper reference limit (URL)] to be significantly associated with repeat revascularization within 48 h after surgery, which was internally validated through random repeated sampling with 1000 iterations.
• They observed the same cut-off predicted 30-day major adverse cardiovascular events and all-cause mortality after a median follow-up of 3.1 years, which was validated in an external cohort.
• Upon decision tree analysis of serial hs-cTnI measurements, they found no added benefit of hs-cTnI measurements in patients with electrocardiographic or echocardiographic abnormalities or haemodynamic instability.
• They further noted that the early post-operative hs-cTnI elevations had a low yield for clinical decision-making and only later elevations (at 12–16 h postoperatively) using a threshold of 8000 ng/L (307× URL) were significantly associated with repeat revascularization with an area under the curve of 0.92.

The authors concluded, " Our results suggest that optimal cut-off values to trigger repeat ICA and decision for repeat revascularization are considerably higher than those recommended by current algorithms, achieve better patient reclassification, and robustly predict short- and long-term cardiovascular outcomes. Indeed, an approach incorporating hs-cTnI levels elevation at 12–16 h with these criteria conferred the best performance."

In a summary report, Dr Salim Hayek wrote, "This study examines the association between hs-cTnI and repeat revascularization to provide cut-offs that could help as a decision-making tool. hs-cTnI levels >500× the URL at 12-16 hours post-cardiac surgery was the optimal cut-off in discriminating between patients without other signs of acute coronary syndrome who required revascularization."

For further information:

https://doi.org/10.1093/eurheartj/ehab918