Angiographic Characteristics of Coronary Disease and Postresuscitation Electrocardiograms in Patients with Aborted Cardiac Arrest Outside a Hospital

The Journal of Emergency Medicine Comment: This study has several significant limitations inherent in its retrospective design. Principally, the significant selection bias for patients that received platelet therapy makes it impossible to compare the two groups within this study. Furthermore, the lack of a regression analysis adjusting for the many confounding variables within the study makes the final results difficult to interpret. Thus, although the results would seem to suggest that platelet transfusions confer no benefit for patients on anti-platelet agents with minor isolated head injury, a more rigorous prospective, randomized trial is still required. , ANGIOGRAPHIC CHARACTERISTICS OF CORONARY DISEASE AND POSTRESUSCITATION ELECTROCARDIOGRAMS IN PATIENTS WITH ABORTED CARDIAC 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 coronary artery occlusion. In this retrospective study, researchers at an academic medical center in Slovenia examined the ECGs of 212 consecutive patients who underwent percutaneous coronary angiography (PCA) after out-of-hospital cardiac arrest, seeking to relate the ECG to a culprit lesion. Three hundred thirty-five patients with out-of-hospital cardiac arrest over a 5-year period were initially examined in the study, with 123 being excluded from PCA due to death before angiography, patients being post-coronary artery bypass grafting, non-ischemic cause of arrest, prolonged down time, physician decision, or other excluding criteria. Of the remaining 212, 158 demonstrated STEMI on ECG and 54 had no evidence of STEMI on ECG, but all underwent PCA. Obstructive coronary disease as demonstrated by PCA was present in 97% of patients with STEMI, of which 89% were presumed acute lesions. Obstructive lesions were present in 59% of patients with no STEMI on ECG, with 24% presumed acute. The authors use these results to advocate PCA in certain patient populations with evidence of STEMI on ECG, as well as patients without evidence of STEMI on ECG after out-of-hospital cardiac arrest. [John D. Anderson, MD Denver Health Residency in Emergency Medicine, Denver, CO] Comment: In patients with evidence of STEMI on post-resuscitation ECG, PCA will likely reveal obstructive lesions, as demonstrated in this and past studies. This study also points to a high incidence of obstructive lesions in non-STEMI patients. However, this high incidence may be a result of physician selection being biased toward performing PCA on patients believed to have coronary artery disease, as many patients without STEMI on ECG were excluded due to physician preference. Prospective studies are needed to further evaluate the true incidence as well as the more important question of outcomes with and without PCA. , DEVELOPMENT AND VALIDATION OF RISK PREDICTION ALGORITHM (QTHROMBOSIS) TO ESTIMATE FUTURE RISK OF VENOUS THROMBOEMBOLISM: PROSPECTIVE COHORT STUDY. Hippisley-Cox J, Coupland C. BMJ 2011;343:d4656.

745 Venous thromboembolism (VTE) is a major cause of morbidity and mortality that is potentially preventable with anticoagulation and other interventions. Although a number of clinical decision rules have been presented in the literature, they are generally designed for use in evaluating patients with presentations concerning for acute VTE. This article, in contrast, is targeted at primary care providers and aimed to predict absolute risk of VTE at 1 and 5 years in asymptomatic patients. The authors used a large research database of data routinely collected from general practices in the United Kingdom to create a prospective cohort of patients aged 25–84 years with no history of VTE, not on oral anticoagulants, and without pregnancy in the preceding year. They randomly assigned patients to either a derivation cohort or a validation cohort. They then identified a broad group of risk factors for VTE based on previously published studies including age, body mass index, tobacco use, congestive heart failure, 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. After extensive analysis, the authors developed an algorithm (available as a calculator online at: http://www.qthrombosis.org) to predict the risk of developing VTE in asymptomatic patients, and used their validation cohort to test their model. The predicted and observed risk correlated well, but with a positive predictive value of only 2.0% for diagnosis of new VTE in 5 years among 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 and a broad set of risk factors to develop a predictive model of the risk of VTE in asymptomatic patients. Despite this, the model reached a sensitivity of only 35.3% and positive predictive value of 2.0% for the development of new VTE among patients in its highest-risk decile. Further studies will need to evaluate the risks and benefits associated with initiating specific prevention strategies based on predictive models like the one described in this article. , FEMALE BREAST, LUNG, AND PELVIC ORGAN RADIATION FROM DOSE-REDUCED 64-MDCT THORACIC EXAMINATION PROTOCOLS: A PHANTOM STUDY. 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 continues to grow and the risk of radiation-induced cancers continues to rise. This is especially true for CT pulmonary embolism (CTPE) studies, which have been shown to be associated with an increased risk of breast cancer, and often are performed on younger patients or in patients who are pregnant. This study compared the phantom organ radiation dose to the breast, lungs, and pelvis from five CT-PE protocols using an anthropomorphic phantom model on a standard 64-detector CT scanner. The five protocols were chosen to represent current scanning practice patterns used to reduce overall radiation in CT-PE protocols with variation in scan length, section thickness, tube potential,