The concentration of highly-sensitive troponin I is increased in patients with brain injury after mild head trauma

Abstract

Although some studies have previously highlighted that myocardial injury may frequently occur in patients with head trauma [1–3], none of them has specifically measured cardiospecific troponins using the novel highly-sensitive (HS) immunoassays, nor the study population has included patients with mild head trauma, i.e., with a Glasgow Coma Score (GCS) ≥14. This prospective investigationwas based on all consecutive patients aged 14 to 80 years, presenting at the emergency department (ED) of the Academic Hospital of Parma (Italy) between September and November 2012 with a history of mild head trauma and GCS comprised between 14 and 15 at presentation. Patients fulfilled the local criteria for mild head trauma requiring CT scanning, due to coexistence of predetermined risk factors. Blood samples were collected within 3 h after head trauma, and serum HS troponin I (HS-TnI) was assessed with the prototype Beckman Coulter HS-AccuTnI on Access 2 (Beckman Coulter Inc., Chaska, Minnesota, USA). The limit of detection and the 99th percentile upper reference limit (URL) of this assay are 2.1 ng/L and 8.6 ng/L, respectively [4]. Unenhanced computer tomography (CT) scanning was performed with 16-slice Siemens Somatom Emotion (Siemens AG, Henkestr, Germany) within 30 to 60 min from ED admission. Positive CT was established in the presence of intracranial lesions, including acute subdural, epidural or parenchymal hematoma, traumatic subarachnoid haemorrhage, cerebral contusion and brain swelling. Significance of differences and frequency distribution of HS-TnI values was assessed with Kruskal–Wallis (for continuous variables) and chi-squared tests (for categorical variables), respectively. Results of measurements were finally reported as median and interquartile range (IQR). Statistical analysis was performed with Analyse-it for Microsoft Excel (Analyse-it Software Ltd., Leeds, UK). The studywascarriedout in accordancewith theDeclaration ofHelsinki, under the terms of all relevant local legislation. The final study population consisted in 42 patients (median age 51 years, IQR 32–72 years; 14 females and 28 males), 8 of whom (19%) with positive CT. No significant difference was found for age (p=0.150) and gender (p=0.172) distributions between CT positive and negative groups. As shown in Fig. 1, the median concentration of HS-TnI was more than 2-fold higher in patients with positive CT (10.3 ng/L; IQR 3.0–20.9 ng/L) than in thosewith negative CT (4.6 ng/ L; IQR 2.7–7.9 ng/L; p=0.003). The frequency of HS-TnI values above the 99th percentile URL was also significantly higher in patients with positive CT than in those with negative CT (i.e., 63 versus 21%; pb0.001). The occurrence of ECG abnormalities in patients with severe brain injury, namely subarachnoid haemorrhage, has been well documented andhas beenattributed to the onsetof reversible neurogenicmyocardial dysfunction secondary to a variety of potential mechanisms including massive catecholamine discharge, tachycardia, hypertension and coronary vasospasm [2,3]. Although a concomitant increase of troponin values measured with conventional or contemporary immunoassays has also been reported in these patients [1,3], no previous study has investigated the concentration of HS-troponin(s) in subjects presenting at the ED with mild head trauma. Increased values of cardiospecific troponins, especiallywhenmeasuredwith novel HS-immunoassays, are the cornerstone for diagnosing both reversible and irreversible myocardial injury [5,6]. Therefore, the results of our prospective investigation provide the first evidence that patients with brain injury after moderate head trauma have a high likelihood of developing myocardial involvement, as mirrored by the remarkable increased frequency ofHS-TnI values above the 99th percentile URL, and should be thereby triaged and monitored accordingly. The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology.