Predicting cardiac risk in noncardiac surgery: a narrative review

Risk stratification endeavors to categorize patients into groups based on the level of risk for each group. Improved perioperative screening tests using more sensitive cardiac biomarkers have revealed that about 68% of perioperative myocardial infarctions (MI) are asymptomatic and may only be detected by routine postoperative screening with troponin measurements. This is important since myocardial injury not meeting criteria for myocardial infarction is associated with increased risk of 30-day mortality (Botto et al. in Anesthesiology 120:564-578, 2014). Traditional risk indices including the revised cardiac risk index (RCRI) and the myocardial infarction cardiac arrest (MICA) index were developed based on overt clinical signs of myocardial infarction and significantly underestimate adverse cardiac events. Recently, brain type natriuretic peptides (BNP) and its precursor n- terminal pro-brain type natriuretic peptide (nt-proBNP) have been shown to be powerful prognostic markers. Incorporating serum biomarkers into updated clinical risk indices is likely to improve their performance. Further studies are needed to determine appropriate clinical interventions to treat isolated elevations in cardiac troponin levels and further mitigate the increased risk of morbidity and mortality. The objective of this review is to summarize the current literature on the clinical diagnoses of perioperative myocardial injury in the setting of noncardiac surgery.