Major limitations of the study were the lack of beta-blockers as an option for rate control and the exclusion of patients with hemodynamic instability, heart failure, and myocardial infarction. As patients with underlying heart disease were excluded, these results cannot be applied to all patients presenting with acute AF.
Bottom line: Compared with digoxin and amidarone, intravenous diltiazem is safe and effective in achieving ventricular rate control to improve symptoms and to reduce length of hospital stay in acute uncomplicated AF.
Citation: Siu CW, Lau CP, Lee WL, Lam KF, Tse HF. Intravenous diltiazem is superior to intravenous amiodarone or digoxin for achieving ventricular rate control in patients with acute uncomplicated atrial fibrillation. Crit Care Med. 2009;37(7):2174-2179.
4) D-dimer Might Be a Reliable Assay to Determine Likelihood of Acute Aortic Dissection
Clinical question: Is the D-dimer assay beneficial in the evaluation of acute aortic dissection (AD)?
Background: Aortic dissection is a potentially lethal disorder that is included in the differential diagnosis of chest pain. No studies exist that specifically examine the use of the D-dimer assay to exclude or predict AD. D-dimer has been proven to be a useful tool to help rule out pulmonary embolism (PE) and DVT.
Study design: Prospective.
Setting: Fourteen centers in the U.S., Europe, and Japan.
Synopsis: Of 220 patients enrolled in the study, 87 had radiologically proven AD, and 133 had an initial suspicion of AD but a different final diagnosis. D-dimer assay was obtained on patients with a suspicion of AD within 24 hours of symptom onset. Additionally, appropriate imaging was performed on all patients to identify AD presence.
D-dimer was found to be a useful “rule out” test. At a cutoff level of 500 ng/mL, the negative likelihood ratio was 0.07 (<0.1 being suggestive of a good rule-out tool) and the negative predictive value was >90%. D-dimer was not shown to be as useful to predict the presence of AD in this study.
A major limitation of the study was a relatively small sample size, especially when subgroups were analyzed, therefore decreasing the overall accuracy of the study. Although this study shows promise for the D-dimer assay in the evaluation of suspected AD, it does not establish D-dimer as a reliable enough test to rule out AD without further imaging or evaluation.
Bottom line: Though this study illustrated a high negative predictive value for D-dimer in AD evaluation, physicians are cautioned against allowing a negative D-dimer to affect their management of a patient with a suspected acute aortic dissection.
Citation: Suzuki T, Distante A, Zizza A, et al. Diagnosis of acute aortic dissection by D-dimer: the International Registry of Acute Aortic Dissection Substudy on Biomarkers (IRAD-bio) experience. Circulation. 2009;119(20):2702-2707.