key: cord-0942790-kctw2nil
authors: Porterie, Jean; Kalavrouziotis, Dimitri; Mohammadi, Siamak
title: Commentary: Preoperative Screening CT: Not Ready for Primetime in The COVID-19 Era
date: 2020-11-07
journal: Semin Thorac Cardiovasc Surg
DOI: 10.1053/j.semtcvs.2020.10.035
sha: f87fe45753c0d5fd7f04d49140d46e17301c96b3
doc_id: 942790
cord_uid: kctw2nil

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Jean Porterie, MD, Dimitri Kalavrouziotis, MD, and Siamak Mohammadi, MD

The coronavirus disease 2019 (COVID-19) pandemic is not only associated with marked global morbidity and mortality, but also poor outcomes after cardiac surgery. 1 In this setting, an effective preoperative screening tool is necessary to optimize cardiac surgical outcomes, especially among asymptomatic patients who may be SARS-CoV-2 positive by reverse transcriptase polymerase chain reaction (RT-PCR).

In this issue of the journal, Knol and colleagues 2 reported the results of a prospective observational study in which they evaluated the role of preoperative thoracic computed tomography: (CT) to screen patients scheduled for cardiac surgery and asymptomatic for COVID-19. Among the 109 patients who underwent CT the day before surgery, abnormal findings, evaluated using a specific grading system (CO-RADS score), were observed in n = 8 (7.3%). Among these, 6 patients had negative RT-PCR for SARS-CoV-2, whereas 1 patient with a normal CT was positive. In a secondary analysis, the screening cohort was matched to a historical pre-COVID-19 control group, in which preoperative chest CT revealed a similar rate of abnormalities (8%, P > 0.999). The authors concluded that in patients undergoing cardiac surgery and asymptomatic for COVID-19, preoperative chest CT had low positive predictive value (PPV), and was abnormal in almost 8% of patients, in whom the presence of COVID-19 was unlikely.

The authors should be congratulated for the timeliness of their study. The initial surge of the COVID-19 pandemic has had an unprecedented impact on health care systems, and resource-intense services such as cardiac surgery have been disproportionately affected. 3 The reallocation of resources had led to the deferral of nonurgent cardiac surgeries in many jurisdictions. 4 The relevance of preoperative SARS-CoV-2 screening has become even more crucial because the early phase of the pandemic has abated, and elective surgeries are resuming. Previous studies 5,6 have pointed out the high accuracy of thoracic CT in the assessment of symptomatic patients or those with high index of suspicion, especially at the beginning of the pandemic when there was uncertainty regarding the availability and reliability of SARS-CoV-2 RT-PCR. However, the utility of chest CT in the screening of asymptomatic patients remains controversial, due to the fact that characteristic imaging features of COVID-19 have been shown to be time-related, and nearly 60% of patients will have a normal CT study during the early phase after the onset of symptoms. 7, 8 Of note, the scoring system used in the study by Knol and colleagues 2 was primarily devised in order to assess pulmonary involvement in patients with at least moderate COVID-19-related symptoms. 9 Other limitations include the low number of patients, variable use of RT-PCR, and protocol deviation in 25% of patients with a "positive" CT. Despite these shortcomings, the results reported by Knol and colleagues 2 are consistent with those of a recent meta-analysis which showed a good sensitivity of chest CT but low specificity, and a low PPV (1.5À48.8%), which in turn is influenced by prevalence (lower PPV in low-prevalence areas). 10 In contrast, the PPV of RT-PCR was much higher (47.3À98.3%). These data suggest that a screening protocol exclusively based on CT imaging would lead to unnecessary postponement of cardiac surgery in as high as 1 in 2 patients. A poorly performing test is especially problematic in the cardiac surgical population, in whom the risk of COVID-19-related adverse outcomes must be balanced against the morbidity associated with an excessive surgical wait time. 11, 12 Thoracic CT screening appears to be valuable in differentiating COVID-19 from viral pneumonitis not related to COVID-19. 13 The findings of Knol and colleagues 2 lend further support to current guidelines 14 which recommend that thoracic CT should not be performed as a COVID-19 screening tool, but order to assess potential pulmonary involvement in light of clinical history, the presence of symptoms, and the results of SARS-CoV-2 RT-PCR. Further studies are needed to investigate the diagnostic and prognostic values of preoperative chest CT in patients referred for cardiac surgery who could have developed pulmonary sequelae after recovering from COVID-19.

Early respiratory outcomes following cardiac surgery in patients with COVIDÀ19

Preoperative chest computed tomography screening for coronavirus disease 2019 in asymptomatic patients undergoing cardiac surgery

Cardiac surgery in North America and coronavirus disease 2019 (COVID-19): Regional variability in burden and impact

Adult cardiac surgery during the COVID-19 pandemic: A tiered patient triage guidance statement

Sensitivity of chest CT for COVID-19: Comparison to RT-PCR

Diagnostic performance between CT and initial real-time RT-PCR for clinically suspected 2019 coronavirus disease (COVID-19) patients outside Wuhan, China

Chest CT findings in coronavirus disease-19 (COVID-19): Relationship to duration of infection

COVIDÀ19 diagnosis and management: a comprehensive review

CO-RADS: A categorical CT assessment scheme for patients suspected of having COVID-19-Definition and evaluation

Diagnostic performance of CT and reverse transcriptase polymerase chain reaction for coronavirus disease 2019: A metaanalysis

Mortality on the waiting list for coronary artery bypass grafting: Incidence and risk factors

Mortality while waiting for aortic valve replacement

Performance of radiologists in differentiating COVID-19 from non-COVID-19 viral pneumonia at chest CT

COVID-19 patients and the radiology department À Advice from the European Society of Radiology (ESR) and the European Society of Thoracic Imaging (ESTI)