Due to the outbreak of SARS-Cov-2, an efficient COVID-19 screening strategy is required
for patients undergoing cardiac surgery. The objective of this prospective observational
study was to evaluate the role of preoperative CT-screening for COVID-19 in a population
of COVID-19 asymptomatic patients scheduled for cardiac surgery. Between the 29th
of March and the 26th of May 2020, patients asymptomatic for COVID-19 underwent a
CT-scan the day before surgery, with RT-PCR reserved for abnormal scan results. The
primary endpoint was the prevalence of abnormal scans, which was evaluated using the
CO-RADS score, a COVID-19 specific grading system. In a secondary analysis, the rate
of abnormal scans was compared between the screening cohort and matched historical
controls who underwent routine preoperative CT-screening prior to the SARS-Cov-2 outbreak.
Of the 109 patients that underwent CT-screening, an abnormal scan result was observed
in 7.3% (95% CI: 3.2 - 14.0%). One patient, with a normal screening CT, was tested
positive for COVID-19, with the first positive RT-PCR on the ninth day after surgery.
A rate of preoperative CT-scan abnormalities of 8% (n=8) was found in the unexposed
historical controls (p>0.999). In asymptomatic patients undergoing cardiac surgery,
preoperative screening for COVID-19 using computed tomography will identify pulmonary
abnormalities in a small percentage of patients that do not seem to have COVID-19.
Depending on the prevalence of COVID-19, this results in an unfavorable positive predictive
value of CT screening. Care should be taken when considering CT as a screening tool
prior to cardiac surgery.
