Lung Opacity and Coronary Artery Calcium Score: A Combined Tool for Risk Stratification and Outcome Prediction in COVID-19 Patients

Abstract

Purpose: To assess and correlate pulmonary involvement and outcome of SARS-CoV-2 pneumonia with the degree of coronary plaque burden based on the CAC-DRS classification (Coronary Artery Calcium Data and Reporting System).

Methods: This retrospective study included 142 patients with confirmed SARS-CoV-2 pneumonia (58 ± 16 years; 57 women) who underwent non-contrast CT between January 2020 and August 2021 and were followed up for 129 ± 72 days. One experienced blinded radiologist analyzed CT series for the presence and extent of calcified plaque burden according to the visual and quantitative HU-based CAC-DRS Score. Pulmonary involvement was automatically evaluated with a dedicated software prototype by another two experienced radiologists and expressed as Opacity Score.

Results: CAC-DRS Scores derived from visual and quantitative image evaluation correlated well with the Opacity Score (r=0.81, 95% CI 0.76-0.86, and r=0.83, 95% CI 0.77-0.89, respectively; p<0.0001) with higher correlation in severe than in mild stage SARS-CoV-2 pneumonia (p<0.0001). Combined, CAC-DRS and Opacity Scores revealed great potential to discriminate fatal outcomes from a mild course of disease (AUC 0.938, 95% CI 0.89-0.97), and the need for intensive care treatment (AUC 0.801, 95% CI 0.77-0.83). Visual and quantitative CAC-DRS Scores provided independent prognostic information on all-cause mortality (p=0.0016 and p<0.0001, respectively), both in univariate and multivariate analysis.

Conclusions: Coronary plaque burden is strongly correlated to pulmonary involvement, adverse outcome, and death due to respiratory failure in patients with SARS-CoV-2 pneumonia, offering great potential to identify individuals at high risk.

Keywords: CAC-DRS Score; Computed Tomography; Coronary Heart Disease; Coronary Plaque Burden; SARS-CoV-2 Pneumonia.

Figure 1

Representative axial (A) and coronal (B) grayscale CT images obtained from a 51-year-old male with SARS-CoV-2 pneumonia after postprocessing of lung opacities using the software prototype on a commercially available workstation (syngo.via, version VB10B; Siemens Healthineers, Forchheim, Germany). The software was capable of providing a colored visualization of lung opacities (volume-rendering technique, VRT), illustrated as red circumscribed areas of lung parenchyma. Abbreviations: SARS-CoV-2, severe acute respiratory syndrome coronavirus type 2. VRT, volume-rendering technique (Color version of figure is available online).

Figure 2

Illustration of patient inclusion (n=142).

Figure 3

The images illustrate a case of a 41-year-old man with confirmed SARS-CoV-2 pneumonia, initially presenting with moderate fever, cough, and limb pain. Due to persistent symptoms, a CT scan was performed after admission (1). Lung parenchyma was typically affected by multiple small patchy areas of ground glass opacities, mainly peripherally located as shown in axial (1A), coronal (1B), and sagittal (1C) grayscale CT images. The overall Opacity Score was found to be at 4.3 RU. Hospital stay was 5 days in total without the need for intensive care treatment. Coronary arteries (2) were not affected by calcified coronary plaques corresponding to a CAC-DRS category of 0 based on both visual and quantitative HU-based assessment (3). Abbreviations: SARS-CoV-2, severe acute respiratory syndrome coronavirus type 2. RU, relative unit. CAC-DRS, Coronary Artery Calcium Data and Reporting System. RCA, right coronary artery. LAD, left anterior descending. Cx, left circumflex. LM, left main (Color version of figure is available online).

Figure 4

Case of a 67-year-old male patient with severe SARS-CoV-2 pneumonia, corresponding to an Opacity Score of 17.6 RU (1). Extensive affection of lung parenchyma on both sides was visible on axial (1A), coronal (1B), and sagittal (1C) grayscale CT images. Coronary sclerosis affected all three vessels showing pronounced plaque formation. CAC values were increased, corresponding to a CAC-DRS category of 3 on visual and HU-based quantitative coronary plaque assessment (3). Abbreviations: SARS-CoV-2, severe acute respiratory syndrome coronavirus type 2. RU, relative unit. PCI, percutaneous intervention. LAD, left anterior descending. CAC, coronary artery calcium. CAC-DRS, Coronary Artery Calcium Data and Reporting System. RCA, right coronary artery. Cx, left circumflex. LM, left main (Color version of figure is available online).

Figure 5

Receiver operating characteristic (ROC) curve analysis showing the diagnostic performance of the Opacity- and CAC-DRS Scores for prediction of mortality in patients with SARS-CoV-2 pneumonia. ROC curve is depicted in blue (composite ROC-curve combining all three scores), green (Opacity Score), red (quantitative CAC-DRS Score), and black (visual CAC-DRS Score). Abbreviations: ROC, receiver operating characteristic. SARS-CoV-2, severe acute respiratory syndrome coronavirus type 2. CAC-DRS, Coronary Artery Calcium Data and Reporting System (Color version of figure is available online).

Figure 6

Kaplan-Meier curve showing overall cumulative survival probability according to the CAC-DRS Score (all p<0.05). Abbreviations: CAC-DRS, Coronary Artery Calcium Data and Reporting System (Color version of figure is available online).