ABSTRACT
Introduction: The relationship between electrocardiograph (ECG) changes and troponin levels after the emergency orthopaedic surgery are not well characterised. The aim of this study was to determine the correlation between ECG changes (ischaemia or arrhythmia), troponin elevations perioperatively and cardiac complications.
Materials and Methods: One hundred and eighty-seven orthopaedic patients over 60 years of age were prospectively tested for troponin I and ECGs were performed on the first 3 postoperative mornings or until discharge. Results: The incidences of pre- and postoperative troponin elevation were 15.5% and 37.4% respectively, the majority were asymptomatically detected. Most of the patients who sustained a troponin rise did not have any concomitant ECG changes (51/70 or 72.9%). Postoperative ECG changes were noted in 18.4% (34/185) and of those with ECG changes, slightly more than half (55.9%) had a troponin elevation. Most ECG changes occurred on postoperative day 1 and were non-ST elevation in type. ECG changes occurred more frequently with higher troponin levels. Postoperative troponin elevation (P = 0.018) and not preoperative troponin level (P = 0.060) was associated with ECG changes on univariate analysis. Two premorbid factors were predictors of postoperative ECG changes using multivariate logistical regression; age [odds ratio (OR), 1.05; 95% CI, 1.005 to 1.100, P = 0.029) and sex OR, 2.4; 95% CI, 1.069 to 5.446, P = 0.034). Twenty patients sustained postoperative cardiac complications; 9 (45%) were associated with ECG changes and 16 (80%) with postoperative troponin elevation. Pre- or postoperative troponin elevation better predicted cardiac complications compared with preoperative ECG changes. Conclusion: Electrocardiograph changes do not necessarily accompany troponin elevations after the emergency orthopaedic surgery but are more likely to have higher troponin levels. The best predictor of postoperative cardiac complications is troponin elevation.Following orthopaedic surgery, approximately 5% of patients sustain cardiac complications which leads to increased morbidity and mortality. The mortality rate after hip fracture is as high as 10% to 26% at 6 months and cardiac-related death are common. Cardiac injury is potentially treatable and therefore early detection of myocardial ischaemia is essential. This has led to studies conducted to determine predictors of postoperative cardiac events including perioperative cardiac troponin and electrocardiograph (ECG) monitoring. Interestingly, patients who are at risk of postoperative cardiac complications may be missed if the standard criteria for the diagnosis of myocardial infarction are applied. For example, recent studies have shown that troponin elevations, a surrogate marker for cardiac injury, occur frequently (up to 53% in 1 cohort) and usually present without symptoms. Troponin elevations are associated with higher mortality at 1 year. In the past, non-cardiac surgical studies have focussed mainly on the vascular population as they have the traditional risk factors for cardiovascular disease. Few orthopaedic studies correlate ECG changes with troponin levels. These studies include a small cohort of orthopaedic patients and have found that postoperative myocardial ischaemia is often silent, occur early after surgery and ECG changes are usually non-Q wave in origin.
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