This meta-analysis (unsurprisingly) confirms that pre-operative troponin levels are post-operatively associated with both major adverse cardiac events and mortality risk.

This sounds obvious, why should we care?

First, there's a difference between evidence and that vague feeling we call common-sense that a disproportionate number of our clinical decisions are based upon.

Surgical patients are getting older and sicker. We need better tools for risk stratifying patients before surgery to improve perioperative planning. Most importantly (though not exclusively) reliably identifying biomarkers for risk allows closer postoperative surveillance and monitoring – which may alter outcomes.

Why troponin?

We already know that troponin I and T are markers of cardiac damage, and unlike brain natriuretic peptide (BNP), troponin assays are readily available in most healthcare settings.

Ok, you convinced me... what did they find?

Analysing 10 studies totally 10,371 patients, they found an association between preoperative troponin elevation and MACE (OR 6.9), and short-term & long-term mortality (OR 4.2 & 2.5). Note though that the confidence intervals were quite wide.

There's always a but... the included studies were all observational in nature, used a variety of troponin assays, and the results were quite heterogenous across the 10. Most importantly, even assuming troponin is an accurate preop risk marker, we don't yet know whether that knowledge will allow us to alter outcomes for these patients.

summary

• Jian-Tong Shen, Miao Xu, Yan Wu, Shi-Hong Wen, Xiang Li, Bing-Cheng Zhao, and Wen-Qi Huang.
• Eur J Anaesthesiol. 2018 Nov 1; 35 (11): 815-824.

BackgroundCirculating cardiac troponin levels are powerful predictors of prognosis in many clinical settings, but their association with outcomes after noncardiac surgery is unclear.ObjectivesThe aim of this systematic review was to summarise current evidence on the association of pre-operative troponin elevation with postoperative major adverse cardiac events (MACE) and mortality in patients undergoing noncardiac surgery.DesignSystematic review of observational studies with meta-analysis.Data SourcesPubMed, EMBASE and Science Citation Index Expanded (ISI Web of Science) from their inception to 1 October 2017.Eligibility CriteriaObservational studies reporting the associations between pre-operative troponin levels and MACE and all-cause mortality after noncardiac surgeries were included.ResultsTen studies met the eligibility criteria. The entire body of evidence addressing the research question was based on a total of 10 371 patients: 4.7 to 68.3% (median 23.8%) of patients had elevated troponin levels before surgery. Elevated pre-operative troponin was significantly associated with short-term MACE (seven studies, 5180 patients: odds ratio (OR) 6.92, 95% confidence interval (CI) 3.85 to 12.42), short-term mortality (five studies, 6103 patients: OR 4.23, 95% CI 2.27 to 7.89) and long-term mortality (two studies, 760 patients: OR 2.51, 95% CI 1.47 to 4.29). The associations remained significant when only multivariate-adjusted results were analysed. Overall, the reviewers' certainty about the summary estimates of the associations was very low.ConclusionCurrent evidence suggests that pre-operative high troponin levels are significantly associated with adverse cardiac events and mortality after noncardiac surgery.Trial RegistrationThis systematic review was registered in the International Prospective Register of Systematic Reviews (Centre for Reviews and Dissemination 42017077837).

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