Aetiology and associated outcomes of myocardial injury as defined by postoperative troponin elevation in high-risk patients after noncardiac surgery: a single-centre retrospective cohort study

Abstract

Background Myocardial injury after noncardiac surgery is common, is frequently clinically silent, and arises from heterogeneous mechanisms. Whether structured aetiological assessment using an existing hierarchical framework is applicable in high-risk patients remains uncertain. The primary aim of this study was to determine the aetiological distribution of myocardial injury in a selectively tested high-risk cohort. Methods This single-centre retrospective cohort study included adults undergoing noncardiac surgery during the years 2017 to 2022. Myocardial injury is defined as a high-sensitivity cardiac troponin T concentration >50 ng L−1 within 72 h after surgery. Troponin was measured in selected high-risk patients, either routinely or at physician discretion. The primary outcome was aetiological distribution, classified by anaesthetists as extra-cardiac or cardiac, using an existing hierarchical adjudication model. Secondary outcomes were inter-rater agreement after independent reassessment and in-hospital mortality. Results Of 6263 patients sampled, 1114 (18%) were diagnosed as having myocardial injury and 954 were analysed. Myocardial injury was classified as extra-cardiac in 544 (57%) and cardiac in 410 patients (43%). Renal failure was the most common extra-cardiac cause (37%) and type 2 myocardial injury the most common cardiac cause (81%). Patients with extra-cardiac injury more often underwent non-elective surgery (78% vs 55%; P<0.001). Inter-rater agreement after reassessment was 78% (κ=0.55), with discrepancies mainly in type 2 myocardial injury. In-hospital mortality in this high-risk cohort was 20% overall, 24% in those with extra-cardiac injury, and 15% in those with cardiac myocardial injury (P=0.002). Conclusions In this single-centre high-risk noncardiac surgical cohort, pragmatic aetiological assessment attributed myocardial injury more often to extra-cardiac mechanisms, which were associated with higher in-hospital mortality. Limited by selective postoperative troponin sampling, these findings warrant future research into the prognostic value of troponin elevations across differing aetiologies.