Predictors of cardiac events in high-risk patients undergoing emergency surgery.

Background: The aim of this study was to determine the incidence of myocardial damage and left ventricular myocardial dysfunction and their influence on outcome in high-risk patients undergoing non-elective surgery.

Methods: In this prospective observational study, 211 patients with American Society of Anesthesiologists classification III or IV undergoing emergent or urgent surgery were included. Troponin I (TnI) was measured pre-operatively, 12 and 48 h post-operatively. Pre-operative N-terminal fragment of B-type natriuretic peptide (NT-proBNP), as a marker for left ventricular systolic dysfunction, was analyzed. The diagnostic thresholds were set to TnI >0.06 microg/l and NT-proBNP >1800 pg/ml, respectively. Post-operative major adverse cardiac events (MACE), 30-day and 3-months mortality were recorded.

Results: Elevated TnI levels were detected in 33% of the patients post-operatively. A TnI elevation increased the risk of MACE (35% vs. 3% in patients with normal TnI levels, P<0.001) and 30-day mortality (23% vs. 7%, P=0.003). Increased concentrations of NT-proBNP were seen in 59% of the patients. Elevated NT-proBNP was an independent predictor of myocardial damage post-operatively, odds ratio, 6.2 [95% confidence interval (CI) 2.1-18.0] and resulted in an increased risk of MACE (21% vs. 2.5% in patients with NT-proBNP < or = 1800 pg/ml, P<0.001).

Conclusion: Myocardial damage is common in a high-risk population undergoing unscheduled surgery. These results suggest a close correlation between myocardial damage in the post-operative period and increased concentration of NT-proBNP before surgery. The combinations of TnI and NT-proBNP are reliable markers for monitoring patients at risk in the peri-operative period as well as useful tools in our risk assessment pre-operatively in emergency surgery.