Cardiac injury and troponin testing after orthopaedic surgery

BackgroundCardiac injury after orthopaedic surgery is an increasing problem particularly in an ageing population. The detection of cardiac injury has been aided by the use of cardiac troponins which has also raised questions about the utility of this enzyme in the post-operative setting.ObjectiveThis review evaluates the diagnosis and pathophysiology of myocardial infarction after orthopaedic surgery and examines how myocardial injury is detected, with particular emphasis on the role of troponin testing.SubjectsEight recent orthopaedic trials evaluating the use of troponin were identified in the literature and included in this review.ResultsThis review found that the diagnosis of myocardial infarction is more difficult after surgery since classic symptoms may be atypical or absent. Therefore, there is more reliance on the typical rise and fall in troponin to diagnose cardiac injury especially because electrocardiograph changes may be hard to detect. The pathophysiology of ischaemia after orthopaedic surgery may be different to ischaemia in the non-surgical setting. The incidence of troponin elevation is between 22 and 52.9% after emergency orthopaedic operations. Of note, patients sustaining a troponin elevation are often asymptomatic. Small studies have found troponin to be a prognostic marker of in-hospital cardiac complications, increased length of stay, increased likelihood of discharge to residential care and death at 1 year. No interventional studies have been published to date.ConclusionCardiac injury is an important complication after orthopaedic surgery. Studies have found that troponin testing can detect asymptomatic cardiac injury. These patients are at risk of poorer outcomes and future research should be directed towards treatment of these patients.