Clinically Significant Blunt Cardiac Trauma: Role of Serum Troponin Levels Combined with Electrocardiographic Findings Ali Salim, MD, George C. Velmahos, MD, PhD, Anurag Jindal, MD, Linda Chan, PhD, Pantelis Vassiliu, MD, Howard Belzberg, MD, Juan Asensio, MD, and Demetrios Demetriades, MD, PhD Background: The true importance of blunt cardiac trauma (BCT) is related to the cardiac complications arising from it. Diagnostic tests that can predict accu- rately if such complications will develop or not may allow early and aggressive monitoring or early discharge. We inves- tigated the role of two simple and conve- nient tests, serum cardiac troponin I (cTnI) and electrocardiogram (ECG), when used to identify patients at risk of cardiac complications after BCT. Methods: Over a 10-month period, 115 patients with evidence of significant blunt thoracic trauma were prospectively followed to identify the presence of clini- cally significant BCT (Sig-BCT), defined as cardiogenic shock, arrhythmias requir- ing treatment, or structural cardiac ab- normalities directly related to the cardiac trauma. An ECG was obtained at admis- sion and at 8 hours. Cardiac troponin I was measured at admission, at 4 hours, and at 8 hours. Transthoracic echocardi- ography was performed when clinically indicated. The sensitivity, specificity, and positive and negative predictive values of ECG and cTnI to identify Sig-BCT were calculated. Clinical risk factors for Sig- BCT were examined by univariate and multivariate analysis. Results: Nineteen patients (16.5%) were diagnosed with Sig-BCT and, in 18 of them, symptoms presented within 24 hours of admission. Abnormal electrocar- diographic findings were detected in 58 patients (50%) and elevated cTnI levels in 27 (23.5%). Electrocardiography and cTnI had positive predictive values of 28% and 48% and negative predictive values of 95% and 93%, respectively. However, when both tests were abnormal (positive) or normal (negative), the posi- tive and negative predictive values in- creased to 62% and 100%, respectively. Other independent risk factors for Sig- BCT were head injury, spinal injury, his- tory of preexisting cardiac disease, and a chest Abbreviated Injury Score greater than 2. Conclusion: The combination of ECG and cTnI identifies reliably the pres- ence or absence of Sig-BCT. Patients with an abnormal ECG and cTnI need close monitoring for at least 24 hours. Patients with a normal admission ECG and cTnI can be safely discharged in the absence of other injuries. Key Words: Blunt cardiac trauma, Blunt myocardial injury, Troponin, Elec- trocardiography, Echocardiography, Car- diac complications. J Trauma. 2001;50:237–243. B lunt cardiac trauma (BCT) refers to a spectrum of injuries ranging from simple electrocardiographic changes to free wall rupture. 1 Since it was first de- scribed in 1676 by Borch, 2 BCT has been the subject of much controversy, 1–6 predominantly because of the imprecise methods of diagnosis. The lack of a well-accepted “gold standard” does not allow the evaluation of the sensitivity and specificity of different diagnostic tests in detecting BCT. The electrocardiogram (ECG) and the MB fraction of creatine phosphokinase (CPK-MB) are easy and convenient tests but are affected by a wide variety of diseases. 7 Echocardiography detects cardiac motion abnormalities but cannot be used as a screening test because it is not immediately available in many institutions. 4 Recently, cardiac troponin serum levels have been used, but with conflicting results. 8 –14 Regardless of the definition of BCT, this entity becomes important only when it is associated with significant symp- toms, such as arrhythmias or hypotension, or causes anatomic defects, such as valvular, septal, or free wall rupture. Patients at risk of developing these complications should be recog- nized early after injury, monitored closely, and treated promptly. On the other hand, patients without such risk should be managed cost-effectively by avoiding unnecessary monitoring and allowing early discharge. The diagnostic tests used should be easy to perform and repeat, inexpensive, and risk-free. In this way, appropriate patients could be screened liberally to identify those at risk of cardiac complications, that is, those who have suffered clinically significant BCT (Sig-BCT). In this study, we evaluate the role of cardiac troponin I (cTnI) and electrocardiography in identifying Sig-BCT. We also analyze risk factors of Sig-BCT that are related to the Submitted for publication August 3, 2000. Accepted for publication October 28, 2000. Copyright © 2001 by Lippincott Williams & Wilkins, Inc. From the Department of Surgery, Division of Trauma and Critical Care (A.S., G.C.V., A.J., P.V., H.B., J.A., D.D.), and the Department of Biosta- tistics (L.C.), University of Southern California Keck School of Medicine and the Los Angeles County + University of Southern California Medical Center, Los Angeles, California. Presented at the 60th Annual Meeting of the American Association for the Surgery of Trauma, October 11–15, 2000, San Antonio, Texas. Address for reprints: Ali Salim, MD, LAC+USC Medical Center, 1200 N. State Street, Room 9900, Los Angeles, CA 90033; email: asalim@ usc.edu. The Journal of TRAUMA  Injury, Infection, and Critical Care Volume 50 • Number 2 237