Prospective study of a non-restrictive decision rule for acute aortic syndrome

Age-Adjusted D-Dimer in Ruling Out Acute Aortic Syndrome

Background. Recently, D-dimer has been suggested as a biomarker to rule out acute aortic syndrome (AAS). Since it increases with age, this study was conducted to reveal whether an age-adjusted D-dimer can increase diagnostic accuracy in ruling out AAS. Method. A retrospective observational study design was used. Consecutive adult patients who visited an emergency room between January 2015 and September 2020 and who underwent a D-dimer test and computed tomography angiography for suspected AAS were enrolled. We calculated the diagnostic accuracy of both the conventional (0.5 μg/ml) and age-adjusted (age × 0.01 in patients >50 years) D-dimer cut-offs. Result. D-dimer was higher in the AAS group (n = 82) than in the non-AAS group (n = 122) (10.85 (3.61–33.12) vs. 0.40 (0.23–1.07), OR: 1.139 (CI: 1.085 – 1.195), $p<0.001$ ). The D-dimer plasma level had an area under the ROC curve of 0.915 (CI: 0.873–0.956) with AAS. At the age-adjusted cutoff point compared to a 0.5 μg/ml cutoff, the sensitivity of 97.6% and the NLR of 0.04 did not change, but the specificity increased by 5.7% to 65.6%, the PPV increased by 3.6% to 65.6%, and the NPV slightly increased by 0.2% to 97.6%. Conclusion. Compared with a conventional method, the age-adjusted D-dimer cutoff may have higher specificity and PPV while maintaining high sensitivity for ruling out AAS.

Electrocardiography-gated CT for acute aortic syndrome: quantifying the potential impact of subspecialty national recommendations on emergency general radiology reporting

AIM

To evaluate the detection of acute aortic syndrome (AAS) and the prevalence of alternative diagnoses that may explain the presentation or require follow-up.

MATERIALS AND METHODS

This was a retrospective, blinded re-evaluation of consecutive electrocardiography (ECG)-gated computed tomography (CT) aortic studies by a cardiovascular radiologist performed between September 2019 and May 2020 in a tertiary-referral cardiothoracic centre.

RESULTS

There were 118 identified examinations, six examinations were excluded leaving 112 (mean age = 61 ± 17; 56% male). Three cases of AAS were present (prevalence 2.7%); only one was reported on initial review. There were no false-positive diagnoses of AAS. The heart was mentioned in 79 (70.5%) reports and 73 (65.2%) of reviews revealed a total of 114 new observations; 111 (97.4%) of these were cardiovascular with 44/112 (39.3%) patients potentially having a significant previously unsuspected cardiovascular diagnosis.

CONCLUSION

The implementation of national clinical guidance to increase testing and improve image quality led to a series of challenges. The real value of ECG-gated CT may lie in detecting other diseases that mimic AAS. With the additional workload, increased subspecialty expertise is required but there needs to be a willingness to learn with an adequate support infrastructure.

Implementation of an aortic dissection CT protocol with clinical decision support aimed at decreasing radiation exposure by reducing routine abdominopelvic imaging

Patients suspected of having an acute aortic syndrome in the ED typically undergo CT of the chest/abdomen/pelvis. However, the overwhelming majority of these exams are negative. With the help of clinical decision support, we implemented a new radiologist monitored 'aortic dissection screening protocol' that forgoes routine abdominopelvic imaging in order to reduce radiation dose without compromising diagnostic accuracy. The purpose of the present study is to assess the performance of this protocol. A retrospective analysis was performed to study the effect of the dissection screening protocol on the diagnostic yield, radiation and contrast dose on a total of 835 ED patients who underwent CT scans for suspected aortic dissection over a 48-week study period immediately before and after implementation of the protocol. 3.4% (28/835) of examinations were positive for an acute aortic syndrome over the 48-week study period with no difference in positivity before and after implementation of the 'aortic dissection screening' protocol, 3.0% vs. 3.7%, respectively (p = 0.57). There was a 14.6% reduction in median radiation dose and a 16% decrease in contrast volume utilization for the total ED population who underwent CT for aortic dissection using any protocol in the period after implementation of the 'aortic dissection screening' protocol. Aortic dissection CT in the ED is negative in the overwhelming majority of cases. A monitored 'aortic dissection screening' protocol that initially images the chest only significantly reduced contrast and radiation dose without reducing diagnostic accuracy for ED patients who underwent CT for aortic dissection.