Elena Zapata-Arriaza, MD
@ElenaZaps
Acute ischemic stroke (AIS) management has changed since the beginning of the COVID-19 pandemic. Chart flows and assessment protocols have evolved with the aim of redirecting stroke and COVID-19 patients to places prepared for their management. The use of thorax CT has been implemented in patients with ischemic stroke, to identify patients infected with SARS-Cov-2, regardless of respiratory symptoms.
At the beginning of 2020, it was difficult for a vascular neurologist to imagine how essential it is to perform an accurate thoracic imaging test in those patients with ischemic stroke. Although these measures have improved patient management circuits, they have also led to an increase in the time to revascularization treatments with the impact that this entails. Taking advantage of the CT angiography protocols performed in stroke codes, evaluating the diagnostic accuracy of apical lung exam to identify patients with COVID-19, has been the authors’ aim.
Esenwa et al. have performed a retrospective analysis assessing the diagnostic accuracy of apical lung exam using a previously reported categorical assessment scheme for COVID-19 specific lung findings, in patients emergently presenting to the hospital with AIS. Final analysis included 57 patients. Apical lung assessment, when used in isolation, yielded a sensitivity of 67%, specificity of 93%, positive predictive value of 19% , negative predictive value of 92%, and accuracy of 92% for the diagnosis of COVID-19, in patients presenting to the hospital for AIS. When combined with self-reported clinical symptoms of cough and/or shortness of breath, sensitivity of apical lung assessment improved to 83%.
Recent meta-analysis has shown that the sensitivity of thorax CT is around 94% with a specificity of 37%, and 89% for SARS-Cov-2 PCR. These data indicate the high usefulness of thorax CT in the triage of patients with AIS; however, this leads to a slight increase in response times in stroke codes, with the burden that it entails for the radiologist on duty. Taking advantage of the imaging techniques that are already used in stroke and assessing their usefulness in screening for COVID-19 in high-prevalence settings is a fundamental way to simplify and shorten response times in a time-dependent pathology such as AIS. The evaluation of the apical lungs, associated with the self-report of symptoms, brings the sensitivity values closer to those obtained with the CRP; however, it is possible that the symptoms of the stroke prevent communicating this information to the patient. Likewise, it is essential to know that the absence of findings in the apical assessment of the lungs does not exclude the presence of COVID-19. Maybe these cases need further validation with Thorax CT or PCR. However, the use of apical lung assessment may be an intermediate step prior to chest CT, given the interesting data on sensitivity and specificity. The authors’ proposal would allow to simplify the work, the flow charts, and the triage of patients with AIS in a situation of care overload.
