The Journal of Emergency Medicine 745

Comment: This study has several significant limitations in-herent in its retrospective design. Principally, the significant se-lection bias for patients that received platelet therapy makes itimpossible to compare the two groups within this study. Further-more, the lack of a regression analysis adjusting for the manyconfounding variables within the study makes the final resultsdifficult to interpret. Thus, although the results would seem tosuggest that platelet transfusions confer no benefit for patientson anti-platelet agents with minor isolated head injury, a morerigorous prospective, randomized trial is still required.

, ANGIOGRAPHIC CHARACTERISTICS OF CORO-NARY DISEASE AND POSTRESUSCITATION ELEC-TROCARDIOGRAMS IN PATIENTS WITH ABORTEDCARDIAC ARREST OUTSIDE A HOSPITAL. Radsel P,Knafelj R, Kocjancic S, Noc M. Am J Cardiol 2011;108:634–8.

After cardiac arrest, post-resuscitation electrocardiogram(ECG) may demonstrate ST- elevation myocardial infarction(STEMI), ST changes, or other findings concerning for coronaryartery occlusion. In this retrospective study, researchers at an ac-ademic medical center in Slovenia examined the ECGs of 212consecutive patients who underwent percutaneous coronary an-giography (PCA) after out-of-hospital cardiac arrest, seeking torelate the ECG to a culprit lesion. Three hundred thirty-five pa-tients with out-of-hospital cardiac arrest over a 5-year periodwere initially examined in the study, with 123 being excludedfrom PCA due to death before angiography, patients beingpost-coronary artery bypass grafting, non-ischemic cause of ar-rest, prolonged down time, physician decision, or other exclud-ing criteria. Of the remaining 212, 158 demonstrated STEMI onECG and 54 had no evidence of STEMI on ECG, but all under-went PCA. Obstructive coronary disease as demonstrated byPCA was present in 97% of patients with STEMI, of which89% were presumed acute lesions. Obstructive lesions werepresent in 59% of patients with no STEMI on ECG, with 24%presumed acute. The authors use these results to advocatePCA in certain patient populations with evidence of STEMIon ECG, as well as patients without evidence of STEMI onECG after out-of-hospital cardiac arrest.

[John D. Anderson, MD

Denver Health Residency in EmergencyMedicine, Denver, CO]

Comment: In patients with evidence of STEMI on post-resus-citation ECG, PCAwill likely reveal obstructive lesions, as dem-onstrated in this and past studies. This study also points to a highincidence of obstructive lesions in non-STEMI patients. How-ever, this high incidence may be a result of physician selectionbeing biased toward performing PCA on patients believed tohave coronary artery disease, as many patients without STEMIon ECGwere excluded due to physician preference. Prospectivestudies are needed to further evaluate the true incidence aswell asthe more important question of outcomes with andwithout PCA.

, DEVELOPMENT AND VALIDATION OF RISKPREDICTION ALGORITHM (QTHROMBOSIS) TOESTIMATE FUTURE RISK OF VENOUS THROMBO-EMBOLISM: PROSPECTIVE COHORT STUDY.Hippisley-Cox J, Coupland C. BMJ 2011;343:d4656.

Venous thromboembolism (VTE) is amajor cause ofmorbid-ity and mortality that is potentially preventable with anticoagu-lation and other interventions. Although a number of clinicaldecision rules have been presented in the literature, they are gen-erally designed for use in evaluating patients with presentationsconcerning for acute VTE. This article, in contrast, is targeted atprimary care providers and aimed to predict absolute risk ofVTEat 1 and 5 years in asymptomatic patients. The authors useda large research database of data routinely collected from gen-eral practices in the United Kingdom to create a prospective co-hort of patients aged 25–84 years with no history of VTE, not onoral anticoagulants, and without pregnancy in the precedingyear. They randomly assigned patients to either a derivation co-hort or a validation cohort. They then identified a broad group ofrisk factors for VTE based on previously published studies in-cluding age, bodymass index, tobacco use, congestive heart fail-ure, chronic renal failure, use of hormone replacement therapy,cancer, and others. The clinical outcome was diagnosis of VTE,including deep venous thrombosis or pulmonary embolism. Af-ter extensive analysis, the authors developed an algorithm (avail-able as a calculator online at: http://www.qthrombosis.org) topredict the risk of developing VTE in asymptomatic patients,and used their validation cohort to test their model. The pre-dicted and observed risk correlated well, but with a positive pre-dictive value of only 2.0% for diagnosis of new VTE in 5 yearsamong patients in the top decile of predicted risk.

[Nir Harish, MD

Denver Health Medical Center, Denver, CO]

Comments:This study utilized a large sample population anda broad set of risk factors to develop a predictive model of therisk of VTE in asymptomatic patients. Despite this, the modelreached a sensitivity of only 35.3% and positive predictive valueof 2.0% for the development of new VTE among patients in itshighest-risk decile. Further studies will need to evaluate therisks and benefits associated with initiating specific preventionstrategies based on predictive models like the one described inthis article.

, FEMALE BREAST, LUNG, AND PELVIC ORGANRADIATION FROM DOSE-REDUCED 64-MDCT THO-RACIC EXAMINATION PROTOCOLS: A PHANTOMSTUDY. Litmanovich D, Tack D, Lin PJ, Boiselle PM,Raptopoulos V, Bankier AA. AJR Am J Roentgenol 2011;197:929–34.

Overall radiation dose from computed tomography (CT)scans has become a concern as the use of CT scans continuesto grow and the risk of radiation-induced cancers continues torise. This is especially true for CT pulmonary embolism (CT-PE) studies, which have been shown to be associated with anincreased risk of breast cancer, and often are performed onyounger patients or in patients who are pregnant. This studycompared the phantom organ radiation dose to the breast, lungs,and pelvis from five CT-PE protocols using an anthropomorphicphantom model on a standard 64-detector CT scanner. The fiveprotocols were chosen to represent current scanning practicepatterns used to reduce overall radiation in CT-PE protocolswith variation in scan length, section thickness, tube potential,

746 Abstracts

pitch, tube current, noise index, and whether dose modulationwas used. The outcomes measured included the total dose inmilligrays to each organ as well as the volume CT dose index(vCTDI: the average dose delivered to the scan volume).When comparing the protocols used during the contrast injec-tion phase of a CT-PE scan, protocol 3, which has been reportedto decrease overall radiation dose to the breast in pregnant pa-tients, did show a significant dose reduction when comparedto protocol 4, which is used in non-pregnant patients (protocol3 breast skin: 4.8 6 1.8 mGy; 91.7% of vCTDI, vs. protocol4 breast skin: 13.1 6 5.5 mGy; 87.0% of vCTDI, p = 0.003).Overall dose to the breast parenchyma demonstrated a similartrend. Protocols used before contrast injection and in regularchest CT protocols demonstrated varying doses, with an exper-imental protocol delivering the lowest breast dose (breast skin:1.9 6 0.6 mGy, breast parenchyma 1.3 6 0.4 mGy). In all fiveprotocols, the lungs consistently received the highest overall ra-diation dose, and the dose to the pelvis was consistently low,never exceeding 0.2 mGy.

[Austin Johnson, MD

Denver Health Medical Center, Denver, CO]

Comment: The increased use of CT scans within the emer-gency department necessitates continued efforts to decreaseoverall radiation doses. In this study, the authors demonstratedthat different scanning protocols can effectively decreaseorgan-specific radiation doses. Unfortunately, they do not com-pare the effectiveness of each scanningprotocol in termsof imagequality and its ability to identify clinically significant pulmonaryembolisms. This study does suggest that CT protocols should betailored to minimize long-term radiation exposure risks.

, CLINICAL EXAMINATION IS HIGHLY SENSITIVEFOR DETECTING CLINICALLY SIGNIFICANT SPI-NAL INJURIES AFTER GUNSHOT WOUNDS. Inaba K,Barmparas G, Ibrahim D, et al. J Trauma 2011;71:523–7.

Rapid assessment of spinal injury in penetrating trauma pa-tients is an important step in the management of these poten-tially seriously injured patients. In an urban, academicmedical center, 282 adult patients with penetrating injurywere enrolled over a 6-month period. These patients had a stan-dardized physical examination of their spine using a checklist inan attempt to prospectively determine the sensitivity and speci-ficity of a structured clinical examination to evaluate for spinalinjury after penetrating trauma. Of the 282 patients, 139 sus-tained a stab wound and none of these patients had a spinal in-jury. Of the remaining 143 gunshot wound (GSW) patients, 112were deemed evaluable (Glasgow Coma Scale score of 15, notintoxicated, with no distracting injury) and underwent a stan-dardized examination including palpation for pain or deformityand complete neurologic examination. All patients were alsoevaluated with computed tomography (CT) scans with spinal re-constructions. Clinical signs of pain or neurologic deficit werepresent in 17.1% of these patients, and of those with positivesigns, 46.2% had a spinal injury. Additionally, 3 total patientshad spinal injury not detected by clinical examination, but all3 were transverse or spinous process fractures and did not re-quire surgical intervention or orthotic stabilization. Thus, the

overall sensitivity, specificity, positive predictive value, andnegative predictive value were 66.7%, 89.6%, 46.2%, and95.2%, respectively. However, for clinically significant injuries,the sensitivity of clinical examination was 100.0%, specificity87.5%, positive predictive value 30.8%, and negative predictivevalue 87.5%.

[John D. Anderson, MD

Denver Health Residency in EmergencyMedicine, Denver, CO]

Comment: Appropriate use of CT scans is an important stepin minimizing radiation exposure for patients, as well as in re-source management. In GSW patients who are evaluable, a fo-cused clinical examination may decrease the need for CTscans to evaluate for spinal injury. Although this study hadfew patients with actual spinal injury, the results are encourag-ing for the reliability of the physical examination. What remainsto be seen is if these findingswould actually translate to a changein practice.

, THE CT-STAT (CORONARY COMPUTED TOMO-GRAPHIC ANGIOGRAPHY FOR SYSTEMATICTRIAGE OF ACUTE CHEST PAIN PATIENTS TOTREATMENT) TRIAL. Goldstein JA, Raff GL, ChinnaiyanKM, et al. J Am Coll Cardiol 2011;58:1414–22.

The evaluation of acute chest pain in ‘‘low risk’’ patients hasbeen a longstanding challenge for emergency physicians. Theuse of serial electrocardiograms (ECGs) and biomarkers to‘‘rule out’’ myocardial infarction (MI), followed by stress test-ing or cardiac imaging, has become the standard of care, butis resource-intensive and expensive. This study evaluated coro-nary computed tomographic angiography (CCTA) as a potentialalternative to the current standard of care. The study was con-ducted as a multicenter comparative effectiveness trial compar-ing CCTA to rest-stress myocardial perfusion imaging (MPI).Patients with acute chest pain and low risk for MI (defined asThrombolysis in Myocardial Infarction [TIMI] risk score < 4)with no ECG changes concerning for acute ischemia and no el-evated serum biomarkers were randomized to receive CCTAvs.MPI. Patients with CCTA showing < 25% coronary arterial ste-noses were eligible for discharge home; patients with 25–70%stenoses were recommended for cross-over for rest-stressMPI, and patients with > 70% stenoses were referred for inva-sive coronary angiography. Importantly, this study was not pow-ered to compare the diagnostic accuracy of CCTA or MPI, butrather their diagnostic efficiency, or time from randomizationto result. The authors found that use of CCTA resulted in a sig-nificantly shorter time to diagnosis and decreased total emer-gency department (ED) costs while maintaining a similarsafety profile. The time to diagnosis using CCTAwas a medianof 2.9 h (25th percentile = 2.1 h, 75th percentile = 4.0 h), com-pared with 6.2 h (4.2, 19.0) for patients receiving MPI, whichwas statistically significant. The authors also found a statisticallysignificant reduction in total ED costs in patients undergoingCCTA compared with MPI. There was no significant differencein major adverse cardiac events over a 6-month follow-up be-tween the two groups.

[Nir Harish, MD

Denver Health Medical Center, Denver, CO]